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Full text of "Notes on the use of machine guns in trench warfare and on the training of machine gun units compiled from foreign reports"

CONFIDENTIAL 



FOR OFFICIAL USE ONLY 



NOTES ON THE 



USE OF MACHINE GUNS 
IN TRENCH WARFARE 



AND ON THE 



TRAINING OF MACHINE GUN UNITS 
COMPILED FROM FOREIGN REPORTS 



i 

V 



California 

.egional 

acility 

I 



ARMY WAR COLLEGE 



MARCH. 1917 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1917 



CONFIDENTIAL 



FOR OFFICIAL USE ONLY 



NOTES ON THE 



USE OF MACHINE GUNS 
IN TRENCH WARFARE 



AND ON THE 



TRAINING OF MACHINE GUN UNITS 
COMPILED FROM FOREIGN REPORTS 



ARMY WAR COLLEGE 



MARCH. 1917 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 
1917 



WAR DEPARTMENT. 
Document No. 580. 
Office of The Adjutant General. 



-tic. 



WAR DEPARTMENT, 

WASHINGTON, May 7, 1917. 

The following notes on the use of machine guns in trench warfare 
and on the training of machine-gun units are published for the 
information and guidance of all concerned. 

[2593173, A. G. O.] 

BY ORDER OP THE SECRETARY OP WAR! 

H. L. SCOTT, 
Major General, Chief of Staff. 
OFFICIAL: 

H. P. McCAIN, 

The Adjutant General. 

3 



MACHINE GUNS IN TRENCH WARFARE, 



In trench warfare as it exists in Europe, automatic machine rifles, 
popularly called machine guns, find their greatest use. Besides the 
trench, the essential elements of a trench line consist of a depth of 
wire and a front of machine guns. 

The tremendous stopping power of machine guns enable them to 
replace a large number of riflemen along this line, reducing to a 
minimum the men employed in actual defense, thereby leaving a 
large part of the force in reserve for use in the counter attack, or for 
the assumption of the offensive at another part of the line. Their 
use also reduces the daily wastage due to sickness, and prevents the 
offensive spirit of the Infantry from becoming impaired. 

Opposing belligerents in the present European struggle soon found 
it necessary to greatly increase the ratio of the number of machine 
guns per 1,000 Infantry rifles to 8, and in some areas to even larger 
figures. This ratio would give about 12 machine guns to one of 
our maximum strength Infantry regiments, and this number may 
be assumed as the minimum that would be required to properly 
defend the front that would be assigned to an Infantry regiment. 

Comparison table of automatic machine rifles in most general use in 

Europe. 





a 


a 


.a . 






8 























bib 




** r . 


s . 


T3 - 






3 


bf 


s 


Name. 


li 


1 


11 


Operating 
force. 


Cooling. 


l| 


1 


5 




& 





X! W 






!& 


] 


1 




d 


- 


5 *4) 






5 


** 


T 




3 


r 


r 5 








0) 


c 




o 




fc 











B 






48 


250 


Explosion and 


Water 


450 to 















- fusee spring. 




500 






Vickers' light 
Colt 


35 


48 
58 


250 
250 


do 

Gas and spring 


...do 
Air 


500 
400 


70 


360 




30 




30 


do 


Air orfchange 


250 to 






able). 










barrel. 


400 








4 nei 


301 


47 


.do 


Air with alu- 


400 
















minum radi- 


















ator. 









1 Jacket filled with water. I 

2 Depending upon adjustment of tripod. 
s Folding. 

With magazine filled, 30 pounds. 



6 MACHINE GUNS IN TRENCH WARFARE. 

TYPES OF AUTOMATIC MACHINE RIFLES. The term 

"machine gun" is popularly applied to all rifles of this character. 
Some foreign authorities, however, are careful to apply the name 
"machine gun " to automatic machine rifles of the Maxim, Vickers, 
and Colt types only, calling those of the Lewis, Light Hotchkiss. 
and Madsen types "Light automatic weapons," for the reason that 
the latter are a cross between the machine gun proper and the 
automatic rifle. The term ' ' automatic rifle ' ' implies a weapon which 
can replace the ordinary magazine rifle in the hands of the individual 
soldier. 

The powers and limitations of these two classes of automatic 
machine rifles have been carefully studied and each is used for the 
work to which it is best suited. The machine gun, or heavier type, 
is used where long-sustained fire of any kind is necessary^ as for: 

(a) Creating bands, or belts, of fire across the front of a defensive 
position. 

(6) Guarding the flanks of an attack by covering areas of ground 
with ftre. 

(c) Long range covering fire. 

(d) Indirect fire, etc. 

The lighter, or Lewis gun_tvpg. has generally been assigned to 
Infantry battalions and is considered ideal for supplementing^the 
lire power of riflemen, assisting them to gain lire .superiority and 
closely supporting thorn on all occasions in either attack or defense. 

The ^ewjs gun type is the first to go forward in an attacjfr and the 
last to be brought away in a retirement. This type enables fewer 
of the machine-gun type to be placed in the front line of an en- 
trenched position, reduces the number of Infantry in the front-line 
trenches, and enables positions won in an attack to be more quickly 
organized. 

THE UNITED STATES AUTOMATIC MACHINE 
RIFLE. The Benet-Mercie machine rifle, model of 1909, is an 
extremely light weapon. The gun alone weighs 30 pounds, or just a 
few pounds more than the Lewis gun, and it can be used in the f ront- 
line trenches or to accompany an Infantry line with the same facility 
that theLewis gun is used for these purposes in Europe at present . The 
Ordnance Department has recently modified a Vickers tripod for 
use with this gun, which will enable it to be used in the support 
trenches and other positions in rear, as are the Maxim, Vickers, 
and Colt machine guns abroad. The tripod weighs 45 pounds and 
can easily be carried by one man in a creeping or crawling position 
over all kinds of ground. 



MACHINE GUNS IN TRENCH WARFARE. 7 

When mounted on this tripod, the Benet-Mercie machine rifle, 
model of 1909", can, upon occasion, deliver overhead fire, long range, 
indirect, and searching fire, traversing fire, etc. 

In other words, our automatic machine rifle can, upon occasion, 
play the r61es of the six types or two classes of machine rifles in use 
abroad. 

The gun has a case for protection against dirt and weather, which 
weighs about 16 pounds, so that the gun in its case weighing about 
46 pounds, and the modified tripod weighing 45 pounds, can each 
be carried by a single man. 

As the War Department has recently adopted the Vickers as the 
heavy type machine gun for the United States Army, it is unlikely 
that the Benet-Mercie machine rifle will be called upon to do any 
work except that to which it is best suited. 

CHARACTERISTICS OF MACHINE GUNS. 

(a) Their power is limited to fire action. Machine guns by 
fire action alone can pave the way for an attack or ^rive back a 
hostile assaujK but they can not gain ground. The latter is almost 7 
exclusively the role; of Infantry, which is capable of crossing all 
obstacles. Whenever, therefore, fire action alone is needed, ma- 
chine guns can be advantageously employed in preference to In- 
fantry, the latter being reserved for fire action combined with~ ^ 
movement. - , 

(6) Nature of fire. Machine gun fire ia cnnpentrajjefj,; therefore 
it will be most effective against a narrow and deep target. As 
Infantry normally advances in extended order, the best means of 
obtaining the above-mentioned target is by the use of oblique or 
enfilade fire. For this reason flanking fire should be the rule. 

Frontal fire should only be used against troops in close formations 
and against approaches, such as roads, bridges, defiles, communica- 
tion trenches, etc.; that is to say, against places where the enemy 
is compelled to take up dense formations on a narrow front. The 
traversing arrangement allows the gun to be turned through a con- 
siderable angle without moving the tripod, and with little exposure. 

(c) Invisibility. Owing to its small frontage it is easier to find a 
concealed position for a machine gun than for an equivalent number 
of riflemen. Hence, the possibilities of surprise effect are very 
great. Surprise is essential for the successful handling of machine 
guns. Flanking fire and surprise effect should always be sought for. 

(d) Mobility. The machine gun can go where a man can go on 
foot. 



8 MACHINE GUNS IN TRENCH WARFARE. 

EMPLOYMENT. 

v 

The general principles governing the employment of machine guns 
are exactly the same in either open fighting or trench warfare, but 
to secure maximum results from the guns on all occasions the best 
method of applying these general principles to the peculiar condi- 
tions of the present war must be studied. 

The machine gun is a weapon of opportunity, but the machine- 
gun commander must not passively await the opportunity. He 
must keep in close touch with the situation and look for or make an 
opportunity for the successful employment of his guns. The ma- 
chine-gun officer must, therefore, be alert and handle his guns with 
boldness and cunning. The gunners must be determined, steady, 
and full of resource and initiative. 

^COOPERATION. Cooperation is essential, not only between 

,-^lhe machine guns of a single organization, but between those and 

the guns of adjacent units. Arrangements must be made for cross 

fire along the entire front, and for covering spaces not reached, or 

reached with difficulty, by artillery fire. 

OPENING FIRE. The general rule that machine guns must 
not open fire until a good target presents itself must not be carried 
to extremes, otherwise opportunities for the infliction of both moral 
and actual damage upon the enemy may be lost. The effect likely 
to be produced upon^the enemy is Ihe guiding^rjrinciple which 
justifies the opening of fire. It is often impossible to see anything 
"bFthe enemy, and likely positions for him to occupy must be looked 
for and these searched with fire, if necessary. 

Well-concealed machine guns may often direct their fire against: 

(1) Windows, doors, and roofs of houses thought to be occupied; 

(2) areas of standing crops and brush; (3) open spaces that small 
parties of the enemy are crossing; and (4) the enemy's firing line. 

NECESSITY may require machine guns to open fire upon un- 
suitable targets to assist the advance of the infantry, or to open fire 
in self-defense. 

SURPRISE EFFECT should always be the aim of the gun com- 
mander. Unless a surprise opening of fire is obtained, the gun de- 
tachment, and perhaps the gun itself, may be put out of action 
before any effect whatever has been obtained. 

POST OF DETACHMENT. As few men as possible should be 
around the gun. Those not actually necessary to work the gun 
should be engaged in the ammunition supply or under cover. 

INTERVAL BETWEEN GTJNS. If liable to be subjected to 
artillery fire, the interval between machine guns should be such 



MACHINE GUNS IN TRENCH WARFARE. 9 

that no two guns will be included in the burst of a single shrapnel. 
This interval should never beJess than 20 yards. The gun positions 
should be such that the guns may give mutual support to one another 
by means of cross fire. Positions close to objects whose range is 
known to the enemy, or near prominent objects that will aid the 
enemy in finding their range, are to be avoided. A position in front 
of a dark background, or in ground covered with a suitable growth 
that will hinder observation, should be sought. During an advance 
or a retrograde movement the guns support each other by advanc- 
ing or retiring alternately, as the case may be. When 



infancy, the machine gjms should mix with the infantry and trv 

to disguise their identity as much as 



TINDER ARTILLERY FIRE. Great care must be taken to 
prevent the machine guns from being located by the artillery. If 
guns are shelled, they must change position at once. A move of 50 
yards will generally be sufficient, f hese alternative or secondary 
j-ingjtjninH will always be select^ in advance. 

It may sometimes be desirable for the detachment to cease firing 
and to retire with the gun under cover until the shelling stops. If 
this is done, the hostile artillery may think the gun has been put out 
of action. When good targets present themselves, the machine guns 
may then open fire again from the same position. 

AGAINST ARTILLERY. The use of machine guns against 
artillery is exceptional. The following cases have been reported 
from abroad: 

(a) A section of machine guns worked forward to a concealed posi- 
tion 900 yards from a field battery in action, and bringing oblique 
fire against the battery, completely silenced it. 

(6) A field battery in action was taken in enfilade by a machine- 
gun section at 2,400 yards. The gunners fled and the battery was 
silenced. 

Frontal fire against shielded artillery will produce moral effect, 
which should be considerable; it should also greatly interfere with 
the supply of ammunition to the guns. 

CARE OF MACHINE GUNS. Every lull in the firing should 
be taken advantage of to clean and oil the gun. Springs should be 
tested and the gun inspected many times daily 'to be sure that it is 
always ready to respond in any emergency. The ammunition must 
be kept rhjaf^ When not in use the gun and ammunition should be 
covered with waterproof covers to protect them from water, dust. 
and dirt. 



10 MACHINE GUNS IN TRENCH WARFARE. 

CONSIDERATIONS GOVERNING THE PLACING AND 
USE OF MACHINE GUNS IN TRENCH WARFARE .The 

answer to the question, "In what way must the machine guns 
at my disposal be placed and used to- best prevent the enemy from 
capturing these trenches?" will decide in almost every case how the 
machine guns must be located, distributed, and used. 

Unless the opposing trenches are so close together that a bombard- 
ment is impossible, an offensive with the object of breaking our line 
will always be preceded by an artillery preparation. The object of 
this bombardment will be to destroy the wire entanglements and 
other obstacles in front of our trenches, to destroy our trenches, 
dug-outs, artillery, machine guns, personnel, and strong points in 
the area to be attacked, and to prevent our reserves from being 
brought forward. 

After what the enemy considers a suitable artillery preparation, 
his grenadiers, infantry, and machine guns will move forward to cap- 
ture our trenches. If he has a superiority of artillery it must be 
expected that he will penetrate our line in places. But we must be 
prepared to receive him with several successive' belts of machine- 
gun fire that will delay him and inflict such losses upon him that he 
will be forced to use up his reserves before gaining any substantial 
advantages. By this time our counterattack should b~e able to drive 
him back with heavy losses. 

The duties of the machine guns of the defense may be enumerated 
to be: 

To replace as many riflemen as possible in the actual defense. 

To prevent the enemy from leaving his trenches. 

To sweep all ground between our trenches and those of the enemy. 

To prevent the enemy entering our trenches. 

To isolate portions of our trenches if captured. 

To sweep communication trenches leading from our front trenches 
to our support trenches. 

To sweep all ground between our support line and front line. 

To provide emergency belts of fire from the rear to replace broken 
belts. 

To engage enemy when concentrating for assault. 

To sweep covered approaches to enemy's defensive line. 

To engage enemy machine guns. 

To sweep ground in rear of the enemy's lines. 

To provide covering fire for counterattacks. 

These duties and the necessity for cooperation and coordination 
of effect require that all machine guns be under the direction of 
one officer. They also require guns to be distributed. 



MACHINE GUNS IN TRENCH WARFARE. 11 

In or near the front line trenches. 

In or near the support trenches. 

In positions in rear along communicating trenches. 

In strong places in rear. 

In reserve. 

The number of guns available will govern the decision as to 
whether machine guns can be placed in all of these positions at 
one time. 

Reports from the present European war indicate that several 
successive lines of defence are not to be aimed at, but rather a 
defended area whose fortifications are laid out according to the 
nature of the ground, giving machine guns freedom of position that 
will not only reduce the chance of their being knocked out, but 
will also reduce to a minimum the number required to form any 
particular, belt or band of fire. 

Reports also indicate that machine-gun defence schemes must 
be divisional, in order to make these belts of fire continuous and 
to enable the construction of machine-gun fieldworks to go on with- 
out interruption. The scheme is worked out so as to hide the 
machine guns from enemy artillery and protect them from hostile 
bombers and snipers. 

LOCATION AND DISTRIBTJTION. In trench warfare, for 
the reasons given above, machine guns are distributed singly along 
the front of the position and in the area to be defended. Some of 
them are placed in the firing trenches, some in emplacements 
between these trenches and the wire entanglements, and some 
behind the parados just in rear of the front-line trenches. The 
positions of those in the firing trenches themselves are generally 
in salients, reentrants, or bends in the trench line. Those in front 
of, or in rear of the trench line, are generally placed in front of or 
in rear of a traverse. All of these locations are positions where 
they can best cross their fire for mutual support and where they 
can best bring an enfilading fire against an advancing infantry line. 

Emplacements in front of the firing line are made by digging 
narrow trenches of the same depth as the firing trench to the front, 
15 or 20 feet, and then turning them to the right or left and widen- 
ing them out to accommodate the guns and crews. The gun rests 
solidly on the ground at the end of this cul de sac which is sunk 
just low enough below the natural ground to conceal it when in 
position. 

Some machine guns are placed along or near the line of the sup- 
port trenches, a short distance in rear. If the shape of the ground 
permits, these are so placed as to fire over the heads of troops in 



12 MACHINE GUNS IN TRENCH WARFARE. 

the firing trenches, to aid in repelling an attack, also to bring fire 
on the first-line trenches in case they should be occupied by the 
enemy. 

Some of the machine guns are emplaced along the communicat- 
ing trenches and some around a strong point, 200 or 300 yards in 
rear of the front-line trenches, in such a way as to stop the enemy 
should he be able to capture the first line and support trenches, 
and to hold him until a counterattack can be delivered. 

TJie remainder of the machine guns are held in reserve, to replace 
casualties, or for use where the commander may decide and for 
instructional purposes. Plates 1, 2, 3, and 4 show the location of 
machine-gun emplacements and the methods of obtaining enfilade, 
covering, and cross-fire along three different fronts in Europe. 
Plates 5 and 6 show some details of the position shown in Plate 1. 

EMPLACEMENTS. In positions in the line where one. can be 
heavily bombarded, machine guns, or at any rate some of them, 
should be kept under cover day and night, but in those portions 
of the line where the enemy is so close that a bombardment is 
impossible and our only fear is a sudden rush, machine guns should 
be mounted in position ready loaded, always at night, and also 
during the daytime when the entanglements will not give sufficient 
time for them to get ready. 

The number of emplacements constructed must generally be 
greater than the number of machine guns assigned to the protected 
area, for guns which come under artillery fire must have an alterna- 
tive or secondary position and there must be emplacements for the 
machine guns in reserve and there must also be emplacements in 
reserve to take the place of those destroyed by the artillery bom- 
bardment. 

The enemy's bombardment of our front line must cease when his 
infantry arrives within about 200 yards of it, but it will increase in 
intensity against the trenches in rear, in order to prevent the infantry 
and machine guns in those trenches from participating in the defense. 
It follows, therefore, that our machine guns must be numerous enough 
along the front line and sufficiently strongly emplaced, so that 
enough of them will survive the bombardment and appear as soon 
as the artillery cone lifts and open fire on our wire entanglements and 
the ground in front of it. 

Owing to the extent of front attacked and to the difficulty of 
artillery observation, it is unlikely that an entire front-line system 
of trenches and machine-gun emplacements will be entirely pulver- 
ized by any artillery bombardment. The experience in Europe has 
been that some machine guns and crews have always survived, ready 



MACHINE GUNS IN TRENCH WARFARE. 13 

to emerge and open a flanking, annihilating fire against the enemy's 
advancing infantry and the more oblique has been this cross fire the 
greater has been its effect. 

The emplacing of guns for cross fire, however, must not be be 
carried to the extreme. While the front of each gun is supposed to 
be protected by the cross fire of its neighbor, if the neighbor should 
meet with mishap or should be under artillery fire and unable to 
perform its function, fire to the front must be arranged for by the 
gun itself. 

Where opposing trenches are close together and machine guns 
would be subject to capture by raid if placed in the front-line trench 
or in front of it, this danger can be avoided by emplacing them 
behind the parados of the firing trench. This position will give a 
better field of fire, and, owing to the feeling of safety which this 
position inspires, the men will work their gun with more coolness 
and judgment than if the gun were sited in the parapet or in front 
of it. 

Plate 12 shows such a gun position connected by an underground 
passage to an ordinary infantry dugout, situated under the parapet. 
In this dugout underground cover is provided for the machine gun, 
its crew, as well as for the infantry squad pertaining to that trench. 
The dugout is also connected with the firing trench. Should the in- 
fantry squad be driven from the firing trench, or should this trench 
be destroyed, they will- take post behind the parados on the flanks of 
the machine gun. 

Plates 7, 8, 9, 10, and 11 show some types of open and protected 
machine-gun emplacements that have been used in the present war. 
If time and materials are available, some of the emplacements and 
dugouts near the front line must be made strong enough to resist the 
heaviest bombardment. 

It must be remembered that the stubborn defense of the front 
trenches will often depend on the machine guns, and that although 
the rifle garrison may sometimes be withdrawn to their bomb proofs 
and dugouts, the machine gunners must remain at their posts. There- 
fore, the machine guns and their personnel must have dugouts and 
emplacements that will survive the bombardment. 

The general experience of the effect of intensive bombardment on 
front-line trenches, when well carried out, has been that large por- 
tions of the parapet have ceased to exist ; and that unless machine-gun 
emplacements in the parapet are dug at ground level and covered 
by heavy beams, heavily supported, they will be destroyed at tho 
same time. A system of strong dugouts behind the parados in which 



14 MACHINE GUNS IN TRENCH WARFARE. 

most of the machine guns can be kept safely during bombardment, 
will make them available when the bombardment is over. 

In connection with the emplacements there must be ample pro- 
tection for look-out men, who are detailed to give the signal for the 
mounting of the machine guns as soon as the artillery cones lift. 
It is reported that concrete emplacements and dugouts have been 
constructed at many important po'nts on the present trench line 
in Europe. 

Dugouts can be made by tunneling deep down under the parapet 
or parados, or by building shelter in a traverse. 

Plenty of earth, well supported by timber and inconspicuous from 
the front, is the aim in their construction. Machine-gun dugouts 
should be near the gun emplacements, and it seems to be the practice 
to build two dugouts for each gun. Into these are carried the gun, 
spare parts, and ammunition during a bombardment when the 
emplacements are too weak to remain in them. 

Emplacements should be constructed to look like the remainder 
of the trench and loopholes should be masked. 

The simplest form of emplacement is a semicircular pit about 2 
feet deep with sand-bag revetment. Emplacements are numbered 
from right to left in any given section. 

Plate 12 shows a simple type of machine-gun loophole. 

Plate 13 is a type used for night firing. 

The simplest form is an arrangement whereby a steel shield and 
one or more sandbags can be removed from the revetment. 

The machine guns in the strong points should be emplaced to fire 
in all directions. The emplacement should be very strong, with 
dugouts, overhead cover, and ammunition depots, all protected by 
snipers and bombers, and the whole surrounded by wire. 

DIMENSIONS OF EMPLACEMENTS, DUGOUTS, AND 
LOOPHOLES. Dugouts and emplacements are made as small aa 
possible. The least dimension for a dugout for 4 men will be found 
to be about 6 by 5 by 4 feet. Minimum dimensions of emplacements 
are about the same, though a minimum of 5 by 4 by 4 feet is reported 
to be in use for both of these in the present European trenches. 

The firing platform must be from 18 to 24 inches below the height 
over which the gun is to fire. 

The loophole is generally 9 inches high by a dimension deter- 
mined by the thickness of the parapet and the number of degrees 
of traverse desired. 

MATERIALS. A loophole box is easily made of 2-inch plank. 
Sleepers of 6 by 4 inch material for roofing and upright posts of 



MACHINE GUNS IN TRENCH WARFARE. 15 

7 by 4 inch dimensions will be found strong enough to use in emplace- 
ments and dugouts. Corrugated iron shegts may be used to cover 
the roof. Some nails will be needed, also sandbags and close mesh 
wire netting for revetting. 

Protection from rifle fire, shrapnel, and splinters from shells, 
bombs, and small high explosive shell from field guns, will generally 
be obtained by a parapet of earth 6J or 7 feet thick. Open emplace- 
ments should have this thickness of earth in front of them. Covered 
emplacements will be splinter proof if there is 20 inches of earth on 
top. 

AMMUNITION. An ammunition chamber must be prepared 
in each emplacement. In this is kept sufficient ammunition for 
immediate needs, a box of spare parts for the gun, oil, and cleaning 
materials. 

All alternative emplacements have these chambers fully equipped 
so that they may be occupied at a moment's notice if the regular 
emplacement has to be abandoned. Ammunition supply must be 
carefully thought out. Reserve ammunition in unopened boxes 
and arrangements for refilling empty strips or belts and making 
repairs are located, with" spare gunners, at a central dugout. Arrange- 
ments must be made to keep ammunition clean, and dry. It should 
be inspected daily. 

RANGE CARDS. Cards are prepared for each emplacement 
and alternative emplacement, giving reference point and ranges 
to all probable targets and to prominent objects. These are left 
in the emplacement day and night, whether occupied or not. Plate 
14 shows a form used abroad. 

QENERAL REMARKS. 

To reduce losses during bombardments, when there is danger of a 
machine gun being struck, it is usual to dismount it, wrap in a water- 
proof covering, and remove it to a safe place, leaving the tripod in 
place so that the gun can be quickly mounted in case of emergency. 
If no safe place is available, the gun is put in the bottom of the 
trench, the waterproof covering preventing its becoming clogged if 
buried by shell fire. Gunners should not retire to the same dugout 
or to the same part of trench. After bombardment two men mount 
the gun, the remainder of the personnel remaining under cover, 
unless the signal of enemy attack is given, when, of course, no 
attention is paid to this precaution. As few men of the gun crew as 
possible, generally 3 or 4, remain in the front trenches, the others 
remain in dugouts and reserve trenches in rear; 



16 MACHINE GUNS IN TRENCH WARFARE. 

One emplacement is iisually reserved for each gun as a "Battle 
emplacement," to be used only in case of enemy attack. Alter- 
native and dummy emplacements are used from day to day for firing 
at such targets as present themselves. A few rounds from these 
will deceive the enemy as to the location of best emplacements, as 
well as the number of guns along the line. Emplacements and dug- 
outs must be kept in good repair. Sandbags, chicken wire, and stakes 
are freely used in repairs. 

In each emplacement the limits that the machine gun can with 
safety be traversed without endangering friendly troops should be 
clearly marked by posts, stakes, or sandbags, arranged so as to make 
traversing beyond these limits impossible. 

OVERHEAD FIRE. Whenever machine guns are going to fire 
over our own trenches, the occupants of the trenches must be in- 
formed. 

LAYING OUT TRENCHES. When entrenchments are dug 
deliberately, they should be laid out with a view to defense by 
machine guns. The machine-gun positions should first be chosen 
and the trenches laid out accordingly, thus enabling the trenches 
to be held by machine guns, supported by a minimum number of 
riflemen. 

POST OF MACHINE-GUN COMMANDER. The commander 
must locate himself centrally so that messages may readily reach 
him, and so that he can coordinate the work of all the guns of his 
command according to the plan of the commander of the troops. 
He must have at hand orderlies and signal men well trained in 
maintaining communication with the different gun positions. 

EQUALIZING DUTIES. To give men and officers of machine- 
gun organizations sufficient rest, a regular roster should be kept. 
As only three or four men are needed with the gun in the front line 
at any one time, the remainder of the crew should be allowed to 
remain in reserve in the reserve trenches or reserve dugouts. This 
will enable men in the front line trenches to be relieved every 24 
hours. Organizations should be relieved as often as possible. 

PERISCOPES. Periscopes should not be used from machine- 
gun position, but to one side of them. 

ILLUMINANTS. Each machine gun in the front line should 
have a Very pistol, or some other illuminant to show up enemy night 
attacks and enable fire to be directed on them. 

SNIPERS AND BOMBERS. When opposing trenches are 
close together, bombers and snipers should be detailed to protect 
the flanks of machine-gun positions. 



MACHINE GUNS IN TRENCH WARFARE. 17 

Also during an attack, the machine guns will be worked to better 
advantage if a few men are assigned to their protection from bombing 
attacks of the enemy. 

ENEMY MACHINE GUNS. When contemplating an attack, 
if enemy machine guns are located, and they are not doing any ma- 
terial damage, it may be advisable to leave them alone, instead of 
firing at them and making them change their positions. Then, 
when our attack is launched, the guns may be in the same position 
and our guns may be able to keep them from firing on our troops. 

OBSERVATION. Officers, noncommissioned officers, and all 
men of maching-gun units must be well trained in the use of the 
telescope, both for observation, of fire and in picking up the enemy's 
machine guns. This requires constant practice. 

CONCEALMENT. Concealment must be aimed at in every 
case. Emplacements are made to look like the surrounding ground, 
so as not to attract the attention of enemy observing parties. Saps 
leading to emplacements are covered with canvas, brushwood, straw, 
sandbags, etc., to prevent photographic location by aircraft. The 
coverings can be easily removed if necessary. 

ORDERS. Owing to the fact that the immediate gun detach- 
ments change each 24 hours and organizations are relieved from 
trench duty frequently, it has been found necessary in the present 
trench warfare in Europe to have the orders for each gun detach- 
ment posted in the gun position so mistakes will not occur. 

These orders prescribe among other things: 

1. That when detachments change, the piece shall be inspected 
that the points shown on the range card be pointed out carefully 
and that report be made whether the gun has been fired during the 
preceding relief; if so, at what target, and from which emplacement. 

2. That fire is to be opened only by order of the gun commander, 
except in a sudden emergency. 

3. That the gun, ammunition, and spare parts shall be cleaned 
and oiled daily. 

4. Hours when gun will be mounted in emplacement. 

5. Other rules necessary for the particular emplacement and the 
care of the gun. 

USE OF MACHINE GUNS IN THE DEFENSE IN 
TRENCH WARFARE. It has been previously stated that when 
machine guns are placed for the defense of an entrenched line, 
the guns of each section of the line must be arranged under the 
direction of one officer. This officer will be the machine-gun officer 
of a brigade, under the supervision of the division machine-gun 
17 2 



18 MACHINE GUNS IN TRENCH WARFARE. 

officer, for the reasons stated. Under hie direction, areas to be 
covered are allotted to each machine gun. These areas should 
slightly overlap. 

In allotting these areas, care must be taken that the whole of the 
area can actually be seen by the man firing the particular gun. The 
mere marking out of theoretical areas of fire on a map is not sufficient. 
It is the custom abroad to prepare a trench map showing the position 
of the machine guns and the areas covered by each. 

Machine-gun officers of adjacent brigades must confer together as 
to the placing of their flank guns, in order to insure that all ground 
in front of the intrenched line can be and will be swept. The 
machine-gun officer also studies the enemy's advanced trenches and 
finds out those portions that can not be reached by our artillery, or 
that can be reached only with difficulty, and arranges his machine 
guns so as to bring enfilade or oblique fire upon them. Fulfilling 
all of these conditions his aim will be to locate his guns so as to create 
several successive belts of machine-gun fire and to place his machine 
guns so as to bring enfilade or oblique fire against the enemy's 
trenches, the ground over which the enemy must pass should he 
attack, and against our own front line trenches should the enemy 
succeed in entering them. 

As previously stated, these objects will generally be achieved by 
placing the guns either in front of the trench, in a bend of the trench, 
in a salient, in a reentrant, or in or near support and communication 
trenches. 

The machine guns should always, if possible, be covered from fire 
from the front, while themselves being able to sweep the front of the 
intrenched line with cross fire. The front of each gun is swept by 
the fire of its neighboring machine gun, but in cases of emergency, 
all guns must have arrangements for firing to their own front. 

Some sandbags can be removed and the machine gun can be fired 
to the front through the loophole thus made, or the gun can be 
quickly removed from the tripod, if mounted, and fired over the 
parapet without it, or it may be fired from some other position pre- 
viously selected. 

DISTRIBUTION OF THE MACHINE GUNS. The shape of 
the ground will determine the distribution of the machine guns to a 
great extent. As a general rule some of the machine guns will be 
placed in or near the front line of trenches, for if it is intended to 
defend the front line obstinately, the machine guns may just make 
the difference between success and failure. Some will usually be 
placed in or near the support trenches to prevent the further advance 
of the enemy should he be able to enter the front line trenches. 



MACHINE GUNS IN TRENCH WARFARE. 19 

If the ground is favorable some will be placed in concealed posi- 
tions in rear and arrangements made to fire over our trenches and 
sweep the ground in front of them, to fire through gaps in oiir line, 
to cover positions from which the enemy might prepare for an assault, 
to bring fire upon positions likely to be occupied by enemy machine 
guns, to assist our own troops to assault by protecting their flanks, 
and by overhead covering fire, and to use indirect fire against ground 
in rear of the enemy's lines. 

Some will, if possible, be placed in strong points farther to the 
rear, that must hold out till a counterstroke can be delivered. 

Any remaining guns are held in reserve to replace those disabled, 
to reinforce threatened points, and for instructional purposes. 

If there are not enough machine guns for all of these positions at 
one time, emplacements should at least be prepared in all of them 
and arrangements made so that machine guns may be quickly placed 
in any of these emplacements, when required. 

Arrangements are also made for rapid communication between all 
parts of the machine-gun defense area, and a quick ammunition 
supply system worked out. 

The brigade machine-gun officer must know the brigade com- 
mander's plans and he must work out ' the whole machine-gun 
defense scheme, so as to coordinate the use of his guns with these 
plans. His post must be near that of the brigade commander, or in 
such a position that he can easily communicate with him. 

USE OF MACHINE GUNS IN THE ATTACK. It has been 
found that continuous trench service impairs the offensive spirit of 
troops; so now when an attack is contemplated, fresh troops, who 
have not recently served in the trenches, are brought forward to 
make it. These are selected troops of best training and highest 
morale. Aeroplane maps of the front to be attacked are obtained 
and carefully studied. Besides distributing guns of different cali- 
bers along the front and collecting large quantities of ammunition 
for use during the artillery preparation, the infantry and machine 
guns are carefully instructed as to their tasks. The machine guns 
must be used in such a manner as to best aid the infantry. The 
brigade machine-gun officer must have full knowledge of the pkn of 
operations at the earliest possible moment, so that he can make 
detailed plans for the machine guns of the whole brigade. These 
plans will be made in consultation with the brigade commander, 
who will, after approval, issue the necessary orders for carrying out 
their part of the plan. 



20 MACHINE GUNS IN TRENCH WARFARE. 

In making his detailed plan for the use of the machine guns of the 
brigade, the brigade machine-gun officer must make a careful study 
of the enemy's front line and its^relation to his own trenches. He 
must also study the ground in rear of the enemy's front line, which 
he will be able to do from the aeroplane maps. 

Machine guns are the weapons most likely to hold up an attack, 
and every effort must be made to locate enemy's machine guns, in 
order that some of our machine guns may be detailed in pairs, if 
possible, to engage them immediately the bombardment ceases. 

After studying the situation in connection with the brigade com- 
mander's plan, the brigade machine gun officer then divides up his 
guns and gives them the individual tasks that will coordinate the 
whole scheme. He must make sure that the machine gun positions 
that he will use at the beginning of the attack are in good condition, 
well supplied with ammunition, and that all arrangements have been 
made for rapid communication. 

In this manner each machine gun, or group of machine guns, will 
have a specific task allotted to it, and before the action commences, 
all concerned will thoroughly understand their duties and the par- 
ticular part that they are to play in the attack. 

All machine guns must be in their allotted places and ready for 
action by the time the artillery bombardment commences. 

THE ALLOTMENT. 

. 1. Some to go forward with the attacking Infantry. The 
number to go forward with the Infantry will be determined by the 
nature of the enemy's trenches, the length of the line to be attacked, 
and the number of machine guns available. These machine guns 
will go forward with the fourth wave of the attacking Infantry, 
mingling with the Infantry so as to make an inconspicuous target. 
These guns will, at first, use the light muzzle tripod. The heavy 
tripod will be brought forward after the Infantry is secure in the 
trenches that it is to capture. 

These machine guns hold themselves ready to go forward at the 
earliest moment and should not open fire until they reach the ad- 
vanced position. 

Their role will be to make good against a counterattack, the ground 
gained by the Infantry, and the approximate locality in which they 
will be mounted in the captured line should be settled before the 
advance begins. 

2. Some to cover the Infantry advance. The positions that 
these machine guns will take will depend upon the configuration 



MACHINE GUNS IN TRENCH WARFARE. 21 

of the ground and the position of the enemy trenches in relation to 
our own, as well as the nature of the attack. 

Their r61e is to deliver a covering and flanking fire. In playing 
this role some of the machine guns will be placed to prevent the cross 
fire by rifles and machine guns from the enemy trenches, situated 
on the flanks of the attack; some to bring oblique and enfilade fire on 
the part of the enemy trenches to be attacked ; and some to sweep the 
ground over which enemy reserves must move to the counterattack; 
some machine guns may be pushed out to the front through saps 
previously prepared to keep down the enemy's fire while our Infan- 
try is getting out of the trenches and through the wire entangle- 
ments. 

All covering machine gun crews should be instructed that when 
our Infantry masks the fire of their guns, they should, if possible, 
direct their fire past the flanks of the attacking Infantry, in order to 
keep down flanking fire and to prevent flank attacks; also, if our 
troops are forced to lie down between the trenches, that these ma- 
chine guns must try to keep down the fire of the enemy's rifles and 
machine guns. 

It must be understood L all commanders, that each machine gun 
has been given a specific task in a concerted plan and that the 
machine guns must not be interfered with or their orders changed 
by any one except the machine-gun commander or the commander 
of the brigade. 

3. Some in reserve under the brigade commander. These 
machine guns will constitute a real reserve and will not be pushed 
into the fight too early. From positions in rear they can aid the 
attack by sweeping ground behind the enemy front line and by firing 
against counterattacks. Indirect fire may be used in these cases, if 
necessary. 

Cases have been reported where machine guns have been used 
to ajd the artillery preparation by firing upon and helping to destroy 
the wire entanglements. Such a use was effective, but the ex- 
penditure of ammunition was not commensurate with results pro- 
duced. 

AMMUNITION SUPPLY. An officer should be placed in 
charge of the ammunition supply, and all arrangements should be 
carefully made for depots and supply before the action begins. 

COMMUNICATION. The brigade machine-gun officer, as a 
rule, remains near the brigade commander. He will prepare for 
communication with all machine guns, or groups of guns, by the usual 
means, as well as by having ft sufficient number of orderlies on hand 



22 MACHINE GUNS IN TRENCH WARFARE. 

for this purpose should the usual means of communication become 
disarranged. 

SUCCEEDING PHASES. If the attack is to consist of more 
than one phase, a separate plan must be made for each advance. 

METHOD OF GIVING ORDERS AND ALLOTTING 
TASKS. Reports indicate that "before an attack the brigade 
machine-gun officer assembles all officers and senior noncommissioned 
officers of the brigade machine gun units, and with the aeroplane 
maps of the enemy's trenches and the defended area to be attacked 
before him, he explains to them the plan of attack, allots the different 
tasks, and designates the position to be taken by each gun before the 
beginning of the attack and the point of the enemy's trench to 
which each will advance during the forward movement, announces 
the location of the ammunition depot, the name of the officer charged 
with ammunition supply, arrangements for communication, his 
position, and gives any other orders pertaining to the special case 
that may be necessary. 

LATE REPORTS. Reports received since this paper was 
written state that machine guns are now being manufactured in 
sufficient quantities to enable the Allies to make full use of them on 
the western front. 

One report states that a machine gun company with 8 guns, of the 
heavy type, has recently been added to each infantry battalion of a 
certain power, and that additional companies, belonging to "a 
machine gun corps," are being formed. 

These latter companies are handled in a manner similar to the 
artillery of the army, that is, they are assigned to special sectors 
according to contemplated operations and to the necessity for 
machine guns. These guns are all of the heavy type and are said 
to be in the proportion of 13 to every 1,000 infantry rifles. 

The report further states that every infantry company has 16 auto- 
matic rifles, weighing 18 pounds each. The power referred to seems 
to use this automatic rifle in the front line trenches as a substitute 
for the Lewis type gun. This automatic rifle is reported to use a 
magazine clip holding 20 cartridges, to fire at the rate of 150 rounds 
per minute, and to be quite accurate up to 600 yards, beyond which 
range the machine gun is used. 

EFFECT OF GAS ON MACHINE GUNS. The effect of gaa 
upon machine guns and cartridges and the method of employing the 
guns during a gas attack are given in the Synopsis of Principles at 
the end of this pamphlet. 



MACHINE GUNS IN TRENCH WARFARE. 23 

TRAINING OF MACHINE-GUN UNITS. 

Most of the belligerents abroad now have "machine-gun training 
centers " to which officers and men selected for machine-gun service 
are sent for several weeks of intensive training before being for- 
warded to their organizations. 

ome of these centers have facilities ior training several thousand 
men, and they keep up a steady flow of trained men toward the front. 
Besides large target ranges, with which all centers are provided, 
there are at these centers facilities for training the personnel in 
grenade throwing, in signaling, and for" giving necessary instruc- 
tion in riding and in the care of animals. 

The sending of officers and men to these centers enables them to 
receive training from selected instructors, insures a uniform system 
throughout the service, and, as machine-gun officers invalided from 
the front are sent to these centers for light duty, the instruction is 
kept up to date. 

' SELECTION OF PERSONNEL. In order to have a depend- 
able machine-gun force which can obtain the best results from the 
guns, a highly trained personnel is necessary. Officers and men 
must know their gun thoroughly. They must understand both the 
theoretical and practical sides of machine-gun employment, as well 
as the theory of machine-gun fire and of trajectories of bullets at the 
different ranges. The personnel should be carefully selected. The 
officers must be intelligent, resourceful, bold, and must have good 
judgment. The work is hard, so the men must have superior 
physique. They should be able to run or crawl from position to 
position carrying gun, tripod, or ammunition. Those unable to do 
this or without staying qualities should be transferred. They must 
have good eyesight. It has been the experience abroad that machine- 
gun units should be composed of men with a mechanical turn of 
mind. In addition to the above qualifications the men should, of 
course, be intelligent and have some education, otherwise they will 
not understand the range and elevation tables and the theoretical 
side of the machine-gun fire and of trajectories of bullets. 

Men selected for machine-gun service are chosen, as far as possible, 
from men who have had from six months' to one year's service in 
one of the other arms. Others selected are very promising men from 
training centers who have completed their preliminary training and 
are ready to take up their machine-gun work at once. 

Officers and men found unfit for machine-gun service are relieved 
or transferred at once. Abroad, every member of the detachment is 
trained in such a manner that he can serve on any duty or position 



24 MACHINE GUNS IN TRENCH WARFARE. 

at the gun. ThJ8 training is necessary, as one shell may disable all 
the numbers operating the gun and the remainder of the detachment 
then engaged in ammunition supply or in reserve in the dugout must 
take over its service. 

After all are trained, the most efficient are appointed gunners and 
so serve until disabled. All officers and noncommissioned officers 
must be expert in the operation of the machine gun as well as in its 
theoretical and mechanical employment. 

PHYSICAL TRAINING. All members of the detachment 
should have daily physical exercises, running, etc. 

Nothing is better than running and crawling considerable distances 
with gun, tripod, and ammunition over all kinds of ground and 
mounting it in all kinds of positions. 

KNOWLEDGE OF GUN. While the officers and noncommis- 
sioned officers of machine-gun units must be experts in everything 
connected with the nomenclature of the machine gun, this knowl- 
edge is not necessary to the men of the gun detachment. It is not 
necessary that they should know the names of all of the parts of the 
gun, but it is necessary that each member of the gun detachment 
should have just as intimate knowledge of the machine gun and its 
parts as an infantry soldier has of his rifle. They should be required 
to take the gun apart and to assemble it again and again until this 
becomes second nature, and they should be quizzed and lectured 
about springs that may become weak and causes of stoppages and 
jama until the ability to locate these also become second nature. 
Not until such intimate knowledge is possessed by each member of 
the detachment can a gun detachment be considered ready for the 
advaced work of machine-gun employment. \ 

FIRE CONTROL. Perfect fire control will require careful 
training of all grades in: 
. 1. Estimating distances. 

2. Pointing out and picking up targets. 

3. Fire orders. 

4. Transmission or passing of orders. 

5. Visual training. 

Visual training is most necessary. It develops the soldier's powers 
of observation and eye for the ground, quickens his intelligence, and 
makes the designation and recognition of targets very easy. 

Training in transmission of orders impresses upon the soldier that 
it is his duty to make certain that all orders passed down are received 
and understood by those for whom they are intended. 

It is believed that the finger breadth and clock systems of target 
designation in vogue in our service can not be improved upon for 



MACHINE GUNS IN TRENCH WARFARE. 25 

training in target designation when the men are sufficiently advanced 
to receive this instruction. 

TRAINING. Assuming that the personnel to be trained is so 
selected that it is ready to begin machine-gun work at once, the 
training of machine-gun units may be divided into the following 
parts: 

1. Mechanical. 

2. Formal drill (as prescribed by the Machine-Gun Drill Regula- 
tions) and training for fire control. 

3. Advanced drill. 

4. Range work. But not a shot should be fired on the range until 
the gunner knows everything about the gun and its use. 

5. Construction and occupation of emplacements, dug-outs, com- 
munication trenches, etc. 

6. Tactical training. 

7. Training with other troops. 

While this training is practically that given for open warfare, the 
present war has proven that this training is sound and adapts itself 
easily to trench warfare whose general principles are exactly the 
same. 

It must be remembered that in no two military operations will the 
situation be exactly the same; therefore, machine-gun units must 
not be trained for any particular conditions of warfare. General 
principles and broad rules alone should guide their training. 

The fire value of a machine-gun well served is considered to equal 
that of at least 50 riflemen in open warfare, and it is claimed by some 
authorities that this value is even much greater in trench warfare. 

To obtain such a volume of fire delivered in the most effective 
manner would seem to justify an enormous amount of time, trouble, 
and expenditure of ammunition in machine-gun training. 

MECHANICAL TRAINING. The importance of this training 
must not be underestimated. Its thoroughness will depend upon 
the mechanical knowledge of the piece possessed by the officers and 
noncommissioned officers. While some of this training must neces- 
sarily be imparted by lecture and informal talks, in the main it is 
practical and must be acquired by the individual gunner himself. 
The machine gun and all accessories are given to each man in turn 
and he is required to take them apart and to reassemble them until 
he is thoroughly acquainted with the place and the use of each part. 
The names of parts are mentioned from time to time until the gunner 
learns the nomenclature of the piece. 

In the same way the individual members of the detachment are 
taught to mount and dismount the gun, to adjust the tripod, and to 



26 MACHINE GUNS IN TRENCH WARFARE. 

dismantle it; to clean, oil, and care for the gun and all of the parts; 
to adjust, read, and set the sights; to load the ammunition strips and 
belts; load, fire, and unload the gun, with dummy cartridges; to feed 
the gun, to locate and remedy stoppages and jams, and to pack and 
unpack gun, tripod, ammunition, and all accessories upon the 
animals. 

Mechanical training must be reviewed and repeated from time to 
time so that the gunners will not become ' ' rusty " in their knowledge. 

FORMAL DRILL AND TRAINING FOR FIRE 
CONTROL. Formal drill, including the allocation of duties of 
all members of the unit, is prescribed by the Machine-Gun Drill 
Regulations. 

TRAINING FOR FIRE CONTROL. This training should 
begin early and should be given daily until all members of the unit 
are proficient, and thereafter the subject should be reviewed fre- 
quently in order that all members may be ready for actual service 
at any time. 

RANGING. The instructor, by lecture and diagrams on black- 
board, explains to the detachment the theory of the trajectories of 
bullets, explaining what is meant by the cone of dispersion, the 
danger zone, the beaten zone, the safety zone, the danger space, the 
100 per cent zone,^the effective zone, the height of the trajectory, 
the line of sight, angle of elevation, etc. 

He also explains why it is necessary to find the correct distance 
or range from the gun to the target, defines ranging, i. e., "Any 
means adopted for ascertaining the sighting elevation required to 
hit a desired object." 

He explains the principal methods of ranging: 

By unit of measure. 
By mil system. 

; In depth . - { By appearance of 

1. By estimating distances..^ h 

Method of averages. 
Lateral. By mil system. 

2. By instruments. (Special course of instruction must be 
given later.) 

3. By observation of bullets. 
Explains other methods of ranging: 

1. By use of maps. 

2. Sound. 

3. Information from other troops. 

4. Forward and back reckoning. 



MACHINE GUNS IN TRENCH WARFARE. 27 

Explains the preparation and use of range cards: 

For attack. 

For defense. 

Explains value and method of observation of fire: 

By signals. 

Methods of communication . . _ 

Telephone. 

Messenger. 

By quiz it is ascertained that the men understand what has been 
told them. The members of the unit are then given careful prac- 
tical courses of instruction in all branches of the subject in the open 
country. Ranging should form a part of each drill thereafter. 

VISUAL TRAINING. As stated previously, the object of 
this training is to develop the soldier's power of observation and eye 
for the ground, to quicken his intelligence and make the pointing 
out (Designation) and picking up (Recognition) of targets easy. This 
training broadens the soldier's military vocabulary and enables him 
to describe intelligently what he sees, as well as to recognize quickly 
what is described to him. 

If landscape targets are available, the instruction may begin at 
the barracks, preceded by a lecture or an informal talk by the in- 
structor. 

He explains: That the accuracy of modern weapons makes 
invisibility a necessity. 

That invisibility is obtained by 

1. Smokeless powder. 

2. Neutral colored uniforms and equipments. 

3. Suitable formations. 

4. Movement carried out under cover of darkness. 

5. Careful study and use of the shape of the ground. 

That a trained eyesight is necessary, due to invisibility of the 
enemy. 

That the men will have difficulty at first in observing and telling 
what they see, due to differences of light, to the different appearance 
of objects in town and in the country, to an undeveloped brain power, 
and to a lack of words (military vocabulary). 

He impresses upon them that the standard each must aim at is 

1. Ability to distinguish the enemy from his surroundings. 

2. Ability to report what he has seen . 

3. Ability to recognize objects described to him . 

4. Ability to train the gun on the desired object. 

5. Ability to study the ground and use it intelligently. 



28 MACHINE GUNS IN TRENCH WARFARE. 

After these preliminary talks the instruction is given in the country, 
where a varied terrain is selected. 

1. Single silhouette targets and groups of these targets are placed 
in different positions, with various backgrounds, and at varying dis- 
tances up to 800 or 1,000 yards. The men are then required to locate 
these targets, describe their location, count the number of figures in 
a group, discuss characteristics of the targets, etc. 

2. Individual men and groups of men then take the place of the 
targets. An officer is sent out with these men to select their posi- 
tions, direct their movements and to cause blank cartridges to be 
fired so as to train the unit in locating sounds. 

The units under instruction then locate, recognize, and describe 
these targets in the same way as was done with the silhouettes. 
They also state the direction of the shots fired, their number, and 
whether they were fired by riflemen or by machine guns. 

3. Definite lines in the landscape, areas of ground, and roads are 
then taken up, examined and described, in detail. 

Areas of ground are then divided into sections, both laterally and 
in depth (i. e., foreground, mid area, and background), and these 
sections are examined and described in detail, as above. 

The above instruction gradually passes into the Designation and 
Recognition of targets. 

The instructor defines Designation, i. e.i/'The shortest and most 
easily understood description of an aiming point by a commander." 

Also Recognition, i. e.: "The gunner's understanding of the exact 
point at which his commander wishes him to aim." 

He explains that accurate ' ' Recognition ' ' is necessary to insure 
that the cone of fire will strike the target desired. 

In this instruction the enemy's front is always pointed out, and the 
target and other objects pointed out must be described as seen by 
the naked eye. This is the normal method. Aids will not be used 
except when necessary. 

Later, when the instruction has advanced sufficiently, the men 
are taught to use the glasses and the telescope; they are also taught 
the "Designation" and "Recognition" of targets by the aid of 

1. Reference points. 

2. Finger breadths. 

3. Clock-face method. 

All of this instruction, besides increasing the military vocabulary 
of the men and teaching them self-reliance, gives them a trained 
eyesight, and soon they will be able to recognize quickly the points 
upon which to aim the gun. 



MACHINE GUNS IN TRENCH WARFARE. 29 

As soon as sufficient progress has been made, the machine gun is 
taken into the open country, where the instructor indicates aiming 
points, and the gun is pointed at the target as the gunner under- 
stands it. The "Recognition" by the gunner is always checked. 

FIRE ORDERS. Whenever fire is simulated, correct fire 
orders should always be given for the class of fire desired, so as to 
accustom the men as soon as possible to receiving and executing 
these orders. 

Before giving "Fire orders," the instructor must give a definition 
of the term, and he must also define "Ranging fire," "Rapid fire," 
"Searching fire," "Traversing fire," "Fire with combined sights," 
"Overhead fire," "Indirect fire," etc. 

He will explain: That the commander will take a position from 
which he can best observe the fire of his guns and the movements of 
his own troops and those of the enemy. 

That "Fire orders" may be verbal, signaled, or written. 

That they will be by word of mouth when practicable. 

That they may be transmitted by orderlies, who must be sure to 
repeat the order correctly and to see that it is understood. 

That ' ' Fire orders ' ' may be given to a single gun, to single platoons, 
to several platoons, or to the whole unit. 

That necessity may require them to be given direct to the squad 
leader instead of through the platoon commander. 

That there may be occasions when orders for the entire unit will 
have to be sent to the right or left gun and then passed from gun to 
gun along the line, and that the commander would then, if possible, 
take a position on or near a flank. 

That where "Fire orders" are given by word of mouth or repeated 
in this manner they must be given calmly, with telegraphic brevity, 
sufficiently loud for everyone concerned to hear, and with pauses 
so that each part may be understood, acted upon, and repeated if 
necessary. 

That it has been found best to designate the range first, to indi- 
cate the target next, and then the number of rounds and class of 
fire. 

That fire is usually begun and stopped by signals. 

That alterations of the range are given by the words "Up" or 
"Down," adding the required amount, as is done by artillery com- 
manders in giving their fire orders. 



< So that after sights are once set it will not be necessary for the gunner to take his 
eyes away from the direction of the target. 



30 MACHINE GUNS IN TRENCH WARFARE. 

ADVANCED DRILL. The scope of the instruction given in 
this class of training will depend upon the ingenuity and the inter- 
est of the officers conducting the training. 

This instruction should be given where there is a varied terrain, 
as it has in view the adaption of the terrain to different assumed situa- 
tions and includes the carrying of gun, tripod, and ammunition by 
crawling and creeping over all kinds of ground to selected gun posi- 
tions without being seen, the occupation of these positions, the 
preparing of range cards to all likely positions of the enemy and to 
prominent objects, simulating suitable classes of fire from these 
positions, the selection of secondary positions and preparing range 
cards for them, the occupation of these secondary positions without 
observation by the enemy and simulating fire from them, then with- 
drawing to a position in rear or on a flank still without being seen, 
practicing fire orders in all of these positions, and communication 
to the rear and to other gun detachments, as well as providing for 
an adequate ammunition supply in all of these situations. 

This instruction naturally merges into tactical training, as the 
line of demarkation is rather dim when instruction is begun on varied 
ground. 

RANGE WORK. This ie perhaps the most important part of 
machine-gun training. After the men have passed tests in their 
elementary instruction, their range training is begun. A varied 
terrain must be selected for the range training in order that the 
proper kind of instruction may be given in all classes of fire. 

The training consists of two courses: 
I. Instructional. 

II. Advanced (including tests for classification and 
combat exercises). 

INSTRUCTIONAL. In this course officers and men are taught 
proper firing positions, correct laying, steady holding, and given 
practice at short known distances in fixed, distributed or travers- 
ing, and searching fire. 

By requiring each individual to prepare the machine gun for 
action, to mount it and make the preliminary tests necessary to 
assure him that the gun is "tuned up, " to set the sights, load, and 
take correct firing position, to hold the gun steady while firing, to 
correct stoppages and jams, and then to unload, dismount, and care 
for the gun, all in turn and without assistance, will develop self- 
confidence, a most necessary quality for a gunner. 

No records are kept of this firing other than of ammunition ex- 
pended and of progress made. No time limit should be imposed. 



MACHINE GUNS IN TRENCH WARFARE. 31 

Each gunner under instruction should have ample time to learn 
his lesson, and when necessary the particular firing exercise should 
be repeated. 

The instructor watches the firer not the target. If mistakes are 
made he causes the fire to cease and makes his criticism. 

Range discipline is carefully maintained and all safety precau- 
tions are taken. 

ADVANCED RANGE WORK. The aim of this instruction 
is to train the units in all classes of fire and to such a degree of per- 
fection that machine-gun commanders may be sure that the fire from 
their guns will be applied to the best tactical advantage when the 
necessities of the combat remove them from the fire direction of 
superior officers. 

The practice includes ranging fire, observation of fire and making 
corrections due to the observation, firing from successive positions, 
firing with combined sights, night firing, searching fire, distributed 
or traversing fire, fire with an auxiliary line of sight, overhead fire, 
fire sweeping reverse slopes, and indirect fire. 

The ranges being unknown, the units apply their previous in- 
struction in finding the correct range, or fire a few ranging shots, 
observing the fire and making corrections. They are taught to 
study climatic conditions and to apply corrections of elevation, as 
well as the use of wind tables. Here they have practice in both 
classes of traversing fire on screens or targets, and they are taught 
how to deliver searching fire without leaving gaps between the 
effective zones. The dangers of overhead fire are pointed out, and 
the units are taught how and when this class of fire may be used with 
safety. They are given practice in sweeping reverse slopes and in 
the use of indirect fire, as well as practice in making necessary prep- 
arations for and executing night firing. 

After this course is completed a classification test is given, in 
which a time limit is introduced and gunners are qualified and rated. 

After the tactical training is well advanced, combat exercises 
are then taken up in connection therewith, the targets and groups of 
targets being arranged to appear at unknown ranges and to fit in 
with the particular tactical situation assumed. 

NOTES ON DIFFERENT CLASSES OF FIRE. An a 
general rule, machine-gun fire will not produce results commen- 
surate with the amount of ammunition expended unless the target 
is included within the area beaten by 75 per cent of the bullets 
directed upon it. 

If an error greater than half tha length of this zone is made in esti- 
mating the range, the fire will be ineffective. The error in a range 



32 MACHINE GUNS IN TRENCH WARFARE. 

obtained by a range finder will probably be 3 to 5 per cent and that 
by other methods may be 10 or 15 per cent. It may also be remarked 
that the probability of error in the range increases with distance. 
The only way to be-sure that you have the correct range is by observa- 
tion of fire, which is not always possible. If observation is possible, 
the observation of a fe\v ranging shots will give you the necessary 
correction, but ranging shots can not be fired when surprise is in- 
tended and is of importance. 

In these cases an effective zone is made certain by the use of 
"Combined sights," or by "Searching fire." 

These classes of fire are used against deep targets, such as bridges 
and roads. 

COMBINED SIGHTS. In this class of fire two or more machine 
guns work together to increase the depth of the effective zone, by 
using different elevations and the same aiming point. The effective 
zone is thus lengthened though the density of fire is reduced. The 
difference of elevation between guns will depend upon the number 
of guns available, after taking into consideration the probable error 
in obtaining the range, and the effective zone for each gun at the 
particular range to be used. The differences of elevation must be 
such that no gaps will be left between the 75 per cent zones of the 
different guns. 

It seems to be the practice to use combined sights differing by 
an elevation of 100 yards for ranges between 800 yards and 1,200 
yards, both inclusive, and sights differing by 50 yards above 1,200 
yards. 

The machine-gun commander must use his judgment in modifying 
the application of the above, in accordance with the facilities that 
he has for accurately obtaining the range, so that the desired tactical 
advantage will be gained without a useless expenditure of ammuni- 
tion. 

Firing with combined sights should be discontinued as soon as 
accurate observation of the strike of the bullets can be obtained. 
A simple way of giving the fire orders for combined sights is to give 
the minimum elevation to a flank gun (usually the left) and to an- 
nounce the difference of elevation desired. If, as a result of his 
observation, or for other reasons, the machine-gun commander wishes 
to alter the sighting, the quickest method will be to bring the ele- 
vation of the left-hand gun above that of the right-hand gun or to 
lower the elevation of the right-hand gun below that of the left- 
hand gun, according to whether the elevation is to be increased or 
decreased. 



/ MACHINE GUNS IN TRENCH WARFARE. 33 

SEARCHING FIRE. This class of fire is used when only 
one or two machine guns are available and combined sights will not 
or are not likely to overcome errors in obtaining the correct range. 
This class of fire requires quite a degree of skill on the part of the 
gunner to avoid gaps in the swept zone. 

The size of the shot groups or bursts to be fired will depend on 
the nature of the target engaged. 

A simple method of using this class of fire is given in one report 
a.s follows: 

When one gun is being employed for searching, the sights arc 
adjusted so that the first shot group will include the lowest range to 
be searched, which is determined by the expected error in the range. 

The gun is now laid on the aiming point and the sights adjusted, 
without relaying the gun, so that the last shot group will include 
the highest range to be searched. The line of sight will now strike 
the ground short of the aiming point. A burst is now fired (10, 20, 
or 30 shots, depending upon the nature of the target), after which 
the elevating wheel is turned to cause the next burst or group to 
strike sufficiently far beyond the first to insure an overlap of the 
effective zones. This is continued until the line of sight is again 
brought on to the aiming point. 

When using two guns, the left gun will act as described above, 
while the sights of the right gun will be adjusted in the first instance 
to the highest limit to be searched and will work down to the lowest 
limit. 

Searching fire will be discontinued when observation of results is 
obtained. 

The effect of ground rising with respect to the line of sight must 
be taken into consideration when either combined sights or search- 
ing fire is employed. 

DISTRIBUTED OR TRAVERSING FIRE. This class of 
fire is employed against a linear target. 

The normal method of traversing is by means of a series of small 
groups, with the object of covering as wide a front as possible and 
producing the desired effect without too great an expenditure of 
ammunition. In the normal method the bursts or groups consist 
of only 5 or 10 shots. 

This method has certain disadvantages. It is slow and requires 
careful training. The effect is a puncturing one at regular intervals 
instead of a mowing effect, which is to be desired. 

The other method of traversing is called the "Swinging traverse." 
In this method the traversing clamp is kept fairly loose, and the 
17 3 



34 

irun is 8W#ng evenly fnm side ;to side. 



in <:a.-e of u 

rush, whjen .11 10 normal me! hod .\vmild bo Ux>. ,s}owv The e.xpemli- 
iinv of ajjruni>^qni / is #o.gra.t when the '-^winging tra\e. 
used that it may be said that : JJt4s)metbod. wjji Jbe reserved tos emer- 
gencies. tfire qa^.be dj^rihuU-d by this method over 30 >. 
front at close ranges in five seconds. 

NIGHT FWNG.-Jf cueuwafrnoi's W J1J allow.it. the gun in 
mounted and laid by day and left till night. At night some kin<l 

of an,ai^xiliajfy akniiig uiaj-kia.p^Uwr^diiP^P^ ^^ 16 ^ un :U1 ^ i" '''"' 
\s-ilh the target This auxiliary aiming- mark caai l> a -crceu sc- 
oured to the open fcide of a box. in which is placed an oniiiuuy jMge 
lantern or au eJei.-iric miv!. Tlit.' screen is marked with linjap to 
permit pf ^e^fphing ^nd traversing within dcfmilo limit.-, li the 
horizontal ilines of the 3?neeij fire [J.,w^ch,^part. ; eadi interval will 
aubtend a t a^^^ IRiWnuteq^h^n jt^BjCE^nis 10 yards from Uu- 
gun. The amount th^t W E^i^wt^s^pr^a^nts in^rangQ |can : bereftfUly 
ascertained t&ftJB the tafclp ,al>Q;ing the -angles of elevation inr lh' 
gun. The .vertrtC-aUinefl ai;e ^^ncj^s .Rpa^j Flfuph/ will give a 
tiou of 2 i^ti^^^Q.jjfarjdft^fr^ftgQi^^^t^screea is in yards 
from the gun. .tnioq sniraif: 91(7 



gun; . pJeitioTR ,js[ ,ei^FK>f4< #P that the un can n< t l>< 
laid during the day or where fire may be necessary from several 
-dUflwr^t;pc^itions i ,aH i ap^eTOep^i.YfJllji,aMe4a be -made ta bring ih, 
gun and tripod up under cover of darkness and mount ijvso as t" 
open fire \sheiv ipquired. t , .-,. i 

Wlu'le itds still light itbe-igUfli-pfisiiJionriigBetepliQd, This of pQurse 
must be selected with reference to the target it w intended t<> <-n- 
gage> Astak^Jafli^pto<^jte!*^<l!airi(JO(j^aLlisifH^ 
gun position and roughly in. Unf) ; with;;<Hi lafget-atid th^.gun posi- 
tioii. The. officer then crawls back to : .tlje gun jxjsition and places 
aistaJfce in thsgrouad in ; a,oeuiiate Higtim^nt with the first stake, and 
the target. Over tfeis last stajke ;the guU -will ,be set up after dark 
The stakes efeould be vertical and th.eioe:atith6gwn poaititai shoul-! 
not be over 6 inches above the ground to avoid-bingi knocked over 
when the tripod is placed over &;>; lf< mor^rihan, one target id to be 
engngedvother etaktw are aligned ,l>?t^-e< < ,th i e ! tlCrgetd au<i the stake 
marking the position <oi |theigun,f iKangoa and, aijiglee .Qf ip-osition -are 
then takeii to the different .Htfgefcv 

"-A vl-uu ?q93i t qmsb gnxaisvifii -:>ih borf; 

6 - VI "66871' 



MACHINE GUNS Iff TRENCH WARFARE. 86 

If owing to the proximity of the enemy, it should be found im- 
possible to place a stake in front of the selected gun position, then 
a stake is first driven at the selected gun position and a stake in 
rear is. placed in^ accurate alignmentr-w ih 'it -an,(Ji the target to be 
engaged. 

A ft or dark a staice'tt)- yards out in front is lined np with the other 
two by means of a trench lanter&s Auxiliary aiming marks are 
placed at night at the exact positions of the 10-yard stakes. The 
tripod is brought forward and set up exactly over the stake at the 
gun position. The gun is then mounted, given the proper eleva- 
tion," and then the line of sight is brought to the intersection of the 
central horizontal and vertical lines of the night firing screen. 

Allowance for wiadage is now made by using the vertical lines of 
the screen. 

One report states that the flash- of the machine giAji in night firing 
will soon disclose its 'position, unless a burlap -iif tain^ia used to 
screen the flash. 



The angle of departure. .Ctak^R^Jfajp -the range tables) is the angle 
between the line of departure of sthje 1 ? bullet and the line from the 
gun to the target. 

The angle of position is the angle that the line from gun to target 
makes with. ..the horizontal line through the gun. 

The quadrant elevation is the angle between the line of departure 
of the bullet and the horizontal line tUjQUgh the gun. It is the sum 
of angle of departure and the angig^of jKj&frJGjtt -jphen the target is 
above the level of the gun and to fck<a dj|lerence of these-angles when 
the target is below the level of the gun. 

In figure 1, the target is on thu same level as the gun, and .the 
angle of position being zero the quadrant elevation is equal to the 
angle of departure. The aiming point is the target. 

In figure 2, the target is above the level of the gun, and the quad- 
rant elevation is equal to the sum of the angle of departure (taken 
from the range table),ajid the angle of position. The aiming point 
is the target. 

In figure 3, the target is below the level of the gun, and the quad- 
rant elevation is equal to aivjrle of departure diminished by the an^le 
of position. Aiming point is the target. 

In figure -I, the liniui; takes place at night and as the target can 
not be seen, an aiming box with a trench lantern inside ia placed at 
A as an aimin.Lr point. 

a The proper elevation will be uhdef^ood from an examination of the figures 
shown below. 



36 



MACHINE GUNS IN TRENCH WARFARE. 




Quadrant Elevation 

Mg. a. 

/.DOT 




of Poaition of A 



5- , 



MACHINE GUNS IN TRENCH WARFARE. 37 

Before dark the range can be taken, the angle of departure (taken 
from the range table), the angle of position and the quadrant ele- 
vation for the target can be determined. After dark, as soon as 
the gun is set up and given the proper elevation, by means of a 
clinometer or other instrument measuring from the horizontal plane, 
the line of sight is brought to the intersection of the central hori- 
zontal and vertical lines of the aiming box by means of the tangent 
sight. 

To hit the target while aiming at A, it is evident that a correction 
has been made in the tangent elevation, which in this case (as seen 
from the figure) is an increase equal to the difference of the angles 
of position of the target and that of the aiming box. 

NOTE. The formula for obtaining the angle of position at any 
range 
Difference in height of gun and 

target, in feet X 19.1=angle of position in degrees. 
Range in yards 

OVERHEAD FIRE. This class of fire refers to machine-gun 
fire delivered, from the rear over the heads of our own troops, either 
in trenches, or advancing to the attack. It may be employed under 
certain limited conditions. One report mentions the following 
factors, all of which tend to increase the difficulty and risk in em- 
ploying fire of this nature and require the working out of a reason- 
able margin of safety: 

1. The state of the machine-gun barrel. 

2. The condition of the tripod and the nature of the ground on 
which mounted. 

3. The degree of visibility of the target. 

4. Errors due to obtaining the correct range and to climatic 
conditions. 

5. Accuracy of laying and holding by the firer. 

The flat trajectory of modern ammunition precludes overhead 
fire at short ranges, for the gun position, our troops, and those of the 
enemy are then practically in the same place. At long ranges the 
dispersion of the cone of fire and the difficulty of getting the correct 
range may make it dangerous. 

This authority says overhead fire, therefore, may normally only 
be employed under the following conditions: 

1. When the machine gun is fired from or a. a commanding posi- 
tion, or across a valley. 

2. When the distance to the target has been obtained accurately, 
that is, by an expert range finder, who can guarantee the distance 
as correct within 5 per cent. 



MACHINE GUNS IN TRENCH WARFARE. 

:<. When the fjurin.T if an expert firer. 

4. \Vlim fin angle of MO minutes is- formed by the intersection of 
imaginar^'line* drawn from tiro target and head* of friendly troops 
lo (begun, the distance to tho target being L-000 yards or under. If 
the dibtkmte to the target IP over 1,000 yards and not more than 
1.500 yard*, the angle thus formed must not he less than M minutes. 
(These angle* may be different with our ammunition and flatter 
trajectory.) 

If the distance to the target is over 1,500 'yards, direct overhead 
fire should not be employed, as the position of the lowest shot of the 
100 per cent c&ne for ranges over 1,500 yards is- uncertain. 

It is remarked b^'t!^&M6ferity that- 1 lie foregoing may be modified 
prtividtd tccdifot and reliable tibsertfition is obtained. This-, how- 
ever, is a matter for the exercise of judgment and common sense on 
the part of the machine-gun commander, for- too ttitich ; reliance must 
not be placefLuppn ; Usability of an observer t6"pick up the cone of 



1he machine-gtm cone of fire ran not l>e ])iekl up correctly. 

There are several methods of obtaining the safety angletfof 30 and 
60 minutes, in use abroad: 

(a) By m'eans of prismatic field-glasses, graticulated for the par- 
ticular kind of ammunition in usel For example, the distance be- 
tween the zero line and the 600 or 700 or 800 yard graticule would 
subtend the desired angle for ranges-1,000 yards or under, white the 
distance between the zero line and trfe T,CfbO or 1,100 yard graticule 
would give the angle for distances between l,000~and 1,500 yards. 
This method of obtaining tire safety angles is 1 unreliable, since it is 
quite possible for the wrong lines to be used. 

(6) By means of a machine gunner's protractor. In this method 
the protractor is held vertically at the full length of the cord' from 
the eye. Lines have jfteVibusly been placed upon the protractor 
at such' a distance from cadi other as to marlc angles of 30 minutes 
and eOTiiinutes when held at a certain fixed distance from' the eye. 

(r) By means of the tangent sight: 

Lay the gun on the target with the correct elevation, then if the 
distance to the target is under 900 yards, move the slide up 400 
yards; if 900 yards or mbre, move up the slide 256 yards. In each 
case adopt the auxiliary aiming mark thus found . Plate 15. (These 
amounts will differ with our ammunition.) 



MACHINE ouire r*r TRENCH; WARFARE. 39 

The report (Hflc'tis^-s'tte advantages and disadvantages of this lat- 
t.-r method as folfow*. 

In one s-enso if is against the pvinviph'S of machine-gun training 
which 'emphasizes the impofctartte of 'the 1 gunner looking 'at the target 
and not alang his sights' when firhig. Again the pinner, having 
carefully maried'the-spot on which the sights are aligned, is trained 
to take the heads of the advancing infantry as his'aiming mark when 
they reach and move in advance of this spot, or rather when their 
heads come into Ma Ifcte of iftgiiti,' a TjIroteMiflg which may not always 
l>e desirable. 

The chief advantages are that eacH gtasvean o>rfairv t'he safety 
angle for the particular troops he is supporting 1 ;' when^t^ trWyps \\ h" 
are being supported' pass tfhe s^>^1ttafrke'd / .a!aA^iniing mark, the 
gniM^'eatt ! stin-contihAi6 > iil^^1)y'e ; l l eVating tlie gufi PO as to main- 
tain his aim on their 'hea*. ' 'AB tttisf ad\-atte^ c6tttfttitrts'/ Irfe aim is 
kept on their heads by turning the elevati^fwTleje!: By'this means, 
ccK'ermgftre is'itidititoined ittWiltHi Mendly troops reach- tlfe-ehemy 's 
position. The conefr'of ffi^'JCass over the heads of iriendlj'- troops 
with a margin of safety at each advance, and seaa^frgrotiild'iii rear 
of the defended position possibly occupied try supports'atod 1 reserves. 

The disadX"Eflitagea ! ol ! M*i4'fethod can 1)6 miflimfeetl' l>y the 
macMne-givfl l c(Wttma<adiei' i U8ittgii: ]>rotractor as a chwk ow tile ifirer, 
and this id 1 particularly ne'efeis6ary'wheft f the nattri-4io*'thf 'ground 
ontd wiiieh'firfe ib being 1 diredWd gives ar'folse impression a r'^arda . 
the limit of safety. 

INDIBfiCT FIBE. This class of fire wilt be need mr fare 
occasions. It is rendered possible by the "fixed mountfeflgf" of the 
machine gun. Lewi&gunfi and others of a similarii!atltfe"mu8f7iCT<?r 
be used, owing to the fact of their being "air cooled" and fired from 
light, mountings. 

I ndirect ftre may be of value in annoying the enenly and 1 affecting 
his morale, but except under unusually favorable conditions, can 
not be expected to inflict serious loss. It may be Used to rover 
areas of ground, to sweep -roads, etc. 

It requires in most cases a great deal of preparation and accuracy 
in calculation. Under certain conditions it mafy positively 1 be 
dangerous to our own troops. Indirect fire facilitates 1 fi*e control, 
since the gunners are 1 not exposed to aimed rifle fire. In''this con- 
nection, advantage' of cOi^eklntentiro^it^^B^my'tfartJltery must 
not be overlooked. 

SPmiT-lJEVET, METHOD. \\ ith (he aid of an ordinary car- 
penter's spirit level, indirect fire can be quickly and accurately 



40 MACHINE GUNS IN TKENCH WARFARE. 

applied with machine guns, to a target which is invisible to the 
firer. The conditions necessary for success with this method are: 

(1) The target must be visible to the controlling officer from a 
position behind and slightly above the gun. 

(2) The gun must be far enough away from the obstruction to 
insure the bullets clearing it. This can only be ascertained definitely 
after the correct elevation has been placed on the gun to hit the 
target. 

(3) The gun and target must be approximately on the same level. 

(4) The controlling officer, or the range taker, must observe the 
fire through field glasses or the range-finding instrument respectively, 
preferably from a flank. 

The method of employing this fire is described as follows: 

(a) The controlling officer raises his head only just sufficiently to 

enable him to give orders to the gunner as to aligning his gun on 

the target for direction only. 

(6) Having finished aligning the gun, as described above, the 

controlling officer now gives the following orders: 

1. Sights at zero. 

2. Level gun with spirit level. 

This is done with the Viewers or Maxim gun by laying the spirit 
level on the top of the breech casings and then by moving the elevat- 
ing wheel until the bubble in the spirit level is central. 

3. Place an aiming mark where sights are now pointing on near 
side of obstruction. 

For example, a stone or handkerchief, or anything the gunner 
can see plainly. 

4. 800 (or whatever the range to the target happens to be from the 
gun position). 

5. Relay on aiming mark. 

6. Ascertain if shots will clear obstruction by adjusting the sights 
for the distance to the obstruction. If the line of sight now clear? the 
obstruction, the cone will also clear. 

7. Fire (or signal of fire). 

Since the gun is now laid with the correct angle of elevation for 
the range to the target on the sights, the bullets will now strike the 
target or in its vicinity. 

Any necessary alterations in elevation or in deflection are made 
according to the results of the fire which will be signaled in by the 
range finder observing through his powerful instrument. 

This method must not be employed when firing over the heads of 
our own troops. 



MACHINE GUNS IN TRENCH WARFARE. 41 

SPOUT LEVEL, CONTOURED MAP, AND ELEVAT- 
ING DIAL. From the map ascertain the distance to and difference 
in height between the gun position and the target. From this work 
out the angle of position in minutes by the formula. 

VIX19.1 

gg =D, 

in which VI is the difference in height of gun position and target 
in feet, HD is the distance from gun to target in yards, and D is the 
angle of position in degrees. 

Add or deduct the angle of position thus found to or from the 
angle of departure for the distance (from range tables), according to 
whether the target is above or below the gun position. This will 
give the quadrant elevation to be placed on the gun. 

To place the required quadrant elevation on the gun: Level the 
gun by spirit level, the gunner holding the while slip dial around till 
zero is under the pointer, without disturbing the bubble. Clamp 
dial to, but without disturbing, the elevating wheel. Some of the 
guns are so equipped that one revolution of the elevating wheel 
equals 4 degrees elevation or depression on the gun. To obtain an 
angle of elevation of 8 degrees, the elevating wheel would have to be 
revolved twice. To set off a lesser amount, use is made of the sub- 
divisions of 5 minutes into which the 4 degrees are divided. These 
5-minute subdivisions are easily subdivided by the eye. 

When the required elevation has been placed on the gun, put a 
suitable aiming mark in position between the gun and target; the 
night firing screen will do for this purpose. Raise the slide of the 
tangent sight as when firing by night without altering the elevation 
of the gun. The direction of the target can be obtained by means of 
the traversing dial, or prismatic compass. During pauses in the 
firing the gun must be relaid on the auxiliary aiming mark. The 
spirit level should also be placed on the gun at frequent intervals 
and the gun leveled. If the zero mark on the dial is then not opposite 
to the pointer, the dial should be undamped and adjusted so that 
the zero mark is in correct position, as described above. The correct 
quadrant elevation should then be placed on the gun and the tangent 
slide altered as necessary. 

CLINOMETER AND CONTOURED MAP .-From the map 
ascertain the necessary quadrant elevation to be placed on the gun. 
Now set the clinometer to the required reading, and place it on the 
cover with the arc to the rear and with the long edge parallel to the 
axis of the barrel. Turn the elevating wheel, the gunner holding 
correctly, till the bubble is central. Place an auxiliary aiming mark 



42 MACHINE GUNS IS TRENCH WARBABE. 

in' 63i8iflai 9!BfeAliip(aiA<jeBr -houl d be placed oh thte-ftfin M frequent 
interval^ and; the elevation checked. JAId O^l 

When firimg-bver theiheadfc of : our awnjtnofrpsiJofclinojn^tef^Kluki 
be used unUxs it^has bewt&ted and; it nectevary.'*cortf)(>tv(\; imme- 
diately prior to firing. 

GRATICTTLE METHOD. Byl kheans of graticules cut across 
the focal planeiof a pair of prisoiatic field- gJassesi! iaidlrtct 1 fee can 
bd iaa qfuickly applied as /ordinary direcfe'fire. 

These graticules represent the angles of devotion for ithegttn- with 
sofae* .pathticHlar bind o/artmunfeHW. Thftitepmlost 'griaticnle 'rbjire- 
sertta i aetw;i an'd life tlbsee belo\r represeskt'eVery 100 yards upward 
from 2001 yards: ; 

Proceed as follow?: . , p ed; c . 

Jj. l 0btain;thBratJge'tath*ftargett:;! ,i- .'.{ b-r 

'2 . Movw to; u iprieitioii'Awlience iyioti can'obBerMe. fene- target tkrbugh 
gratitulatetttifield-glaseeai look at the target in('T!ioiri<i wfeyithot' tihe 
gzitusui r^presentiHg. the raiige-'tfat tha> tajg^t i faMs- afciOBs the targets, 
then-Aodc I or/ suitable aiming mark- above; th&targB* !('h>k;hi-fflmTng 
marki Bidtetr Ue viaibleifrom the-posit>ton.wheiSa;thtegBnTJs"Hi)Dunted) 
and >*ee/ whidh( graitt6le;fail8 across* this- aiiriingi'inirb J 

(Ehe* frange^DorareBpond ing; to this gratictilei givefe tlic'angfe of de- 
parture at -wihDch t; to open-^ife; neing;the snitaible' aiiiung mark to 
lay the gun on.' B^thlsimeandigaieat'accaraDy'ie obtained -white' the 
gua and* ifirer are invisible to tbe^^neiny. ; b 

.Uhis >methbd ibecomei;iiiaccnraie' wben'the seVe of tb^offt^i<ndhg 
theigiatfksdated'glaBsfee is morethani^ feat'tftxiiJe-'thegan, 

I tr is iioportanti 1x ; get i an : aiimirig ; m ark virtnaaltyl abavd i the 'target, 
maktB^ianyfiiTeceBsary aWowafloe ioY'Whid. If itib fotikld neeessttrV 
to increase or decrease the elevation afte? fi?e ihab been opehedy 
sirid^ the posJtibni of /the 1 ! slide does nbt> indicate the 1 range tovthe 
taasget, arioliberi nwthod' :othef than the norinal'muftt be 
( There are roughly as i many, clicks on th*: ritch( ot'it 
sight as there aire ]kiiadke<j8'oiiyad8'iii theirtulg^ ti4llirangeq bdb\r- 
1,500 yardel) > 

IiONG BA1T&E SEARCHING FI3l!Bi--In ttenelb "warfaiv, 
where the positions of our own and the enemy's t&6ps!af!e^ie9*Jy 
marked, long>rdnge^6ilrtHi^r^d^r^thea>6^ 
may eomtetimtefl'be saiilyf employed. 

Tb' abtanr the best resnlfa^ observation vrf thre 1 strike of tlib bnliets 
ia eesetokifiit; The element of chance, daw to* errors ifi 1 raaging, cli- 
inatic conditions, etrora as to the exact poaitJlon of the guto; etc., 
will thus be removed. 



MACHINE GUNS IN TRENCH WARFARE. 4ft 

When observation of results is possible, fire may be directed on 
the hostile support or .reserve, lines, communication tren< -lie.--, ci<-. 
When no observation is posniblp, the moat that can b<; hoped fur is 
to engage an area) of grotiad with the object' of sweeping reverse^ 
slopes of hills which are defiladed from fire at> sthbrfc ranges, inter- 
rupting trallic on roads, etc. 

To insure the safety of our own troops;! the- following must at all 
t inios l>o strictly adheiVxl to: 

I. No target should be engaged at a r&nge of less -than 1,500-yards. 
L>. Tim guns must never 'be more> Ihafar I/, 500 yards -distant from 

bodies of out- own troops, over \vhom they asre'firing, 

3. \\lien 1 the guna are 1,000 yasdB' or; under "fromf ourntrdops. the 
range at which' they' are fired must be such aaJta-ididureitlie'ceriter of 
the cone Wf fii*e psu&rig at- least 60 feet oven theai) beads. 

When the guns are between 1,000 yards andiJi,50^ yapdiEroin our 
o\vn troops, this height rmtst bo 12& f(3et. 

4. The p>isit ton of OT*T own ''troops: with-, reference 'ticJ the gun nmst 
be accurate! y> ascertained. 

>. Whon there is ^negative aoagle of pasitiorrf between i the gttn. and 
target, or a positive angle of position between the.gU!n ! and ! ou!F own 
troops, the heights shown iii the trajectory tab-le -will be reduced. 
The guns musl. therefore, beiileved back t6 fire at a-raflge<whichiwiil 
give the required' safety limits' iiihder these tfondifionfi. 

6. Climatic conditions must be carefully sthidied. i 

7. As a -slight sinking of the tripod d^in^/tho'ficingtiiflayae'rioualy 
al'fcct the safety of offf own troops, owing to 1 the aiitierdd'ahgle^of dle- 
vation, every precaution must be taken to prevent this happening. 
The legs of the tripod' should be firntlyimbeddediin'the'groUnd, and 
provision made to prevent tlien\ ino vingft-om' their original rjoeition. 

8. When "traversing" and "searching" is used, provision- must 

be made in the shape of wooden battens, etc.. to limit them to a safe 

?,V\<}\?, vAiV!^ sw\'\vw;>, 
amount. 

9. A worn barrel should not be used. 

10. All calculations must be carefully checked before firing*. 

I 1. Troops over whom fire ia iff be opened must be cautidned, 
and a certificate to this effect signed by the machine-gun cenimaider. 

12. Clinometers-, if used, must be tested, and if necessary, cor- 
rected, before use. To direct fire on a targets invisible to the gtme, 
a map having a scale of not loss than 3 inchest to one mile must be 

us. M!. In order to find the correct elevation, the map must be con- 

_ 
toured, tenrooa ed y 



44 MACHINE GUNS IN TRENCH WARFARE. 

The following information is required from the map: 

The exact position of the gun, the direction and distance between 
the gun and the target, and the angle of positkih of target with re- 
spect to the gun. Small errors in the position of the gun will cause 
serious errors in direction. 

The position of the gun on the map can be found by "resection. " 
(Par. 34, Engineer Field Manual.) 

The direction of the target can be obtained bv means of a compass 
bearing, or by the use of the traversing dial. 

To find the direction with the traversing dial proceed as follows: 

Select some convenient object visible from the gun position, which 
can be identified on the map for use as a reference object. On the 
map draw lines from the gun position to the reference object and 
target. Measure with a protractor the angle formed by these two 
lines at the gun position. 

Place the gun in position on the ground and lay on the reference 
object. Note the reading shown by the pointer on the dial. Add 
or deduct this reading from the angle already obtained from the 
map, according to whether the reference object is to the left or 
right of the target. 

When the reference object it is desired to use can not be identified 
on the map, its compass bearing must be taken from the gun posi- 
tion and "plotted" on the map. The required angle can then be 
measured and used with the traversing dial as before. 

To place the required elevation on the gun use either of the 
methods of "Indirect fire" previously described (spirit level or 
clinometer). 

To facilitate the making of notes on angles of elevation, bearings, 
safety of our own troops, etc., it is advisable to enlarge the area to 
be engaged. 

SiOPCS 



(<-- /tOO yds. 

I 




By selecting the most suitable range it is easy to adjust the fire of 
machine guns, so that reverse slopes of hills may be accurately swept 
by grazing fire. 



MACHINE GUNS IN TRENCH WARFARE. 4.5 

The following example will show how the suitable range is selected : 

From a contoured map it is noted that the enemy occupies a crest 
line 180 feet above sea level, the 160-foot contour being 300 yards 
in rear of the crest line. 

Our troops are in position in a valley which is 120 feet above sea 
level. 

Deduct 120 feet from the other two heights; the heights above 
our position are seen to be 60 and 40 feet, respectively, and our 
bullets are required to descend from 60 feet to 40 feet in 300 yards; 
that is, from 60 feet to 54 feet in 100 yards. 

Now, inspect the trajectory table (Publication No. 1923, Descrip- 
tion and Rules for the Management of the United States Rifle, Caliber 
.30, Model of 1903). Any fall of 6 feet in 100 yards will not do, as 
it is necessary to arrange that the bullet shall first rise to 60 feet. 
On inspection it is found that the 1,600-yards trajectory satisfies the 
condition as to rise of 60 feet and that there is approximately the 
required fall (from 61.7 to 56.1 feet) between 1,100 and 1,200 yards. 

If, then, a line is drawn on the map 1,100 yards from the crest 
line and machine-gun fire is directed from a point on the line so 
arrived at, at the crest line, with sights at 1,100 yards or the angle 
of , departure equivalent to this, plus the angle of position of the 
crest, the bullets will sweep the reverse slope. 

The above method determines the best position for covering fire 
and aids in selecting positions for machine guns for night fire. 

RANGE TABLES AND FIRING DATA. Plates 15 and 16 
show two kinds of range and firing data cards in use by one of our 
allies. They are prepared for each kind of ammunition used. A 
graticule card for both classes of ammunition is also shown. 

AIDS IN THE DETERMINATION OF RESULTS OF 
FIRE. Screens of suitable size, covered with paper, are used at 
some of the training centers for determining the results obtained 
from different classes of fire. For example, if it is intended to 
sweep the reverse slope of a ridge or hill, several of these screens are 
placed along the slope to be swept and between bursts results are 
signaled, or after the exercise, the number of hits are counted. 

If there is to be practice in overhead fire, rows of these screens 
represent our troops at different stages of their advance and the safety 
angles for this class of fire are determined by sighting at the tops ol 
the screens. There must be no hits on these screens. Other screens 
represent the enemy. 

In the same way screens represent troops on a bridge, along a road, 
Dr the positions of supports and reserves, when practice is had, in 



4 MACHINE &TTNS IN TRENCH WARFARE. 

"searehHig/ 1 otifefingiwith combined sights and -also during night 
firing. 

CONSTRUCTION OF EMPLACEMENTS, DUGOUTS. 
COMMUNICATION TRENCHES, ETC. At all tniininy ..ni<-r- 
aBectionof a > '<def ended 'amV or a system of fjold workp, has been 
laid out and constructed according to the conditions imposed by the. 
terrain, with firing Srenohes/ support trendhes, all kinds of emplace- 
ments 'foe giiaehiiaei gimg, dugouts, eofcuarinidatioir trenched, reserve 
<lucroiitsvr*tottntki ( <!!h*mbeW3,ie!itangleHi;cnte< lookoxit 'poets. lines 
of communications, etc., ju*;sts' *hey- exist at tfae- front/ ' These are 
kept in re, pair and" gvadUailiyeiitended by the labor of the men under 
training. : > At <th'e i prbpe*!tiie^ during the training peried> hiaohine- 
.min uiri^dcttpyi&ese enticements and are taught the routine- of 
i ho t renches,' vlitriag * B44rt)r periods*. They c<id<ict l >'ntght lirinir 
f^rtf'tft^splac^mentsand are tau-^ht tlicir duties ]>otlv in attack 
arid defettee iifldea 1 cotiditiohA as : realistic y'thtey ^n 'be-iide. 

TAOTTOAIi TRAINING. 

tfe '<l)^Bed^nnaifeali^e land study of ground. A rcoorinaiisarice 
May %te toddfe'iri-t^oi ^ayfej'l. ., by 'actually^ going 'd^p-the ground 
attd 1 fey tuitfyikg4t \*ith( glasses, 

The latter-will 'b^She moet usual metHodV^theJtraiHing'initHc 
study of the ground, eeleeiioii of gun pofltioiisJ'cdrtceAted lines of 
adV^S'smd *te*ri-y l ^WI,%ttJbt ! Ae continual-arid thoft>fc: ; -: 

All gttide'8isiHi 1 4ffi^*fe'^d 'fett 
Aoiifif c^nstant'fy p^aet 

selecting 'gvttf' p^iflons. liii.-s of axlvance, et<., in advance of that 
pomtr'-'Tlfey'SWeff'g* *tfr^a^ ttfrftW if their Belec^tidn has *^ 
correct - n7/ ' 0lla (>8 ^ ; ^ noijinirmmf; io .'tod TH rn 



directed to occupy the positions chosen 1 .' ! -The officers ! 
moVements, correct eifors, or suggest better methitfeW eaying^mt 
the movements. 

(2) Selection of gun position^. Daily in?trm-ii<.n should be 
given in the selection of gun positions. Ati dffieei-^ecoftipttnied by 
a range-finder servant makes The selection. The actual 1 position of 
the gun must te chosen from a lying position, ihe person -selecting 
the position raising himself on hi? elbows until his eyes are on the 
level of the gunner \vheu firing the gun. 

The officer also selects the position from which he will command 
the guns. The range-finder sergeant, as soon as a position has been 
setefte^d', make's 'a' range card for the position, entering thereon the 
ranges to all prominent objects. The range-finder sergeant muef hot 



MACHINE G-TTNS IN TRENCH WARFARE. 47 

accompany the Officer so closely as to make a roiiHpifuoim target for 
the enemy. 

The office then 'selects an alternative position for each gnn, which 
must be capable of being reached under cover from the first gnn 
position, and the range-tinder sergeant then i prepares a range card 
for that petition. 

(3) Method of oring-ing: up the guns.-'*Ba'fihg ulcered a gun 
position, the officer signals i., i!-.-- sergeant whose squad is to occnr.i- 
it to join him. The position oi the .-un the <;: ;.-. me range card, 
and the route of "the'gtm'toJte posi-ti ..u -an* then .-riven \<-, sergeant, 
and he condiictefci^squa^cr.siirnali' it to its' position 

The ;*-:.;:: li^proactoes-^Adef 'cover to a point us near the position 
as possible before unpacking gun, tripod, and ammunition. 'From 
this pwition theseare carried forward by hand. 

The member carrying the tripod leads and sets it up under the 
direction of the sergeant. The member with the gun comes next. 

Then come the ammunition, spare part?, extra barrel, en . Th; 
packs are moved >to a tmitable covered position, if possible, out :' 
the direct line of fire. ! It -should not be necessarv ( <j : - ;: an \ orders 
to the noncommissioned Officer in char 1 - m the -parks. He should 
be trained to >ke4p ; theT& ufidet cover and to maintain communu-a- 
tion between them and the guns, sending notice of any' chancre in 
his position. 

(4) Arrangements for ammunition supply.- Ore:'! anention 
must be given to the maintenance of an adequate ammunition sup- 
ply. Too much ammunition must not be carried to the gun posi- 
tion, for in case of a retirement or a sudden chancre of position it, may 
be lost. Ammunition carriers-bring up limited amounts, being eare- 
ful not to expose themselves and thus give away the position of the 
gun. If the distance to the packs is great, a relay will be formed, 
the carrier from the pack meeting the carrier from the gnn at a 
halfway point. 

(5) Methods of communication. In training, all methods of 
communication should be used and prsictieed; i. o., orderlies, sema- 
phore, other methods of visual signaling, and telephon* 

Fire orders and target designations should be given habitually on 
the ground by these methods, and always in the lying position, so 
as to practice communication, as well as the habit of concealment 
so necessary when in the presence of the enemy. 

(<j; Reference points. These should be selected by the 
niachine-g\in commander and communicated as soon as possible to 

the sqiiaid leaders', so as to make the pointing out of targets < 

. 



48 MACHINE GUNS IN TRENCH WARFARE. 

(7) Likely targets. Squad leaders and members of the squad 
should be practiced frequently in selecting places that are likely to 
be occupied by the enemy. Officers should also select these posi- 
tions and point them out to the men. This practice will train the 
men in finding such positions and will make the pointing out and 
recognition of targets easier. 

(8) Changes of position. Practice should be given in with- 
drawing the gun quickly from one position and occupying an alterna- 
tive position without being observed from the direction of the enemy. 

(9) Enemy's machine guns. One or two guns should be sent 
to take up positions that would likely be occupied by the enemy 
and then the squads should be practiced in locating them by sound 
and with telescopes. 

(10) Team work. This practice is most valuable. It consists 
in teaching cooperation by the different squads in concentrating the 
fire of all guns upon a particular target, changing the fire to another 
target, distributing thd fire among several targets, crossing fire with 
that of neighboring guns, using traversing fire by some guns, and 
overhead fire by others and other combinations. 

(11) Choice of gun positions. Questions of concealment and 
the kind of fire desired will have great weight in the choice of a gun 
position; i. e., whether we desire 

Enfilade fire. 

Overhead fire. 

Long-range fire. 

Fire against houses, etc. 

Fire against enemy's machine guns. 

Concealment from enemy's artillery. 

Other considerations may control the choice, as 

Lines of advance and retreat. 

over for ammunition carriers. 

Facilities for control of guns. 

Alternative positions. 

Positions to be avoided have been mentioned before, such as 
obvious positions, or those easy for the enemy to pick out, and those 
easy to observe, as well as those near prominent objects, etc. 

TRAINING OF MACHINE-GTJN UNITS IN COMBINA- 
TION WITH OTHER TROOPS. No training can be considered 
complete unless the machine-gun units have been trained in combi- 
nation with other troops. 

In this course of training, the different units should, in turn, be 
given all of the different rdles that machine-gun units will have to 
play on the field of battle in open warfare, and in both classes of 



MACHINE GUNS IN TRENCH WARFARE. 49 

trench warfare. Careful and repeated instruction is given in the 
different duties necessary in an attack of the enemy's trenches in 
trench warfare; i. e., that of accompanying the infantry line, of 
protecting the flanks of our line, in the delivering of overhead, 
supporting fire, or of indirect, searching fire against the supports 
and reserves of the enemy, etc. 

None of this training should be given until the machine-gun 
units are more or less expert in all of the different kinds of training 
outlined above, especially that classed as range work. In this train- 
ing, the theoretical principles of the previous instruction are actually 
applied with troops and the lessons taught are brought out, as well 
as the importance of cooperation not only between the guns and 
the troops they are assisting but also the necessity for close cooper- 
ation between the guns themselves. 



SYNOPSIS OF PRINCIPLES APPLICABLE TO MACHINE 
GUNS IN TRENCH WARFARE. 



COOPERATION. 

Between machine guns of any particular section of a defensive 
line. 

Between machine guns of adjacent sections and brigades. 

All ground in front swept by cross fire, forming belt of fire. 

Machine-gun commanders and section commanders must be 
conversant with the situation. 

Cooperation of machine guns from a flank against points where the 
enemy is very close must be arranged for. 

TAKING OVER TRENCHES. 

Before taking over trenches, the machine-gun commander 
should, if possible, reconnoiter the whole line and note 

Position of each machine gun and area covered by it. 

Number, position, and nature of any extra emplacements, dug- 
outs, splinter lookout posts, or other work to be done. 

Positions and methods of communication between himself and 
his officers commanding sections, and between them and their 
guns. 

He then issues any necessary machine-gun orders. 

BO1CBARDMENTS. 

With a view to reducing losses during bombardments observe 
these rules: 

During bombardment by the enemy, dismount machine guns and 
place them in strong dugouts, or if none, in bottom of trench. 

Tripods are left in position, so guns can be mounted quickly. 

Machine guns when dismounted will be wrapped in strong water- 
proof covers to prevent clogging with dirt from shell fire. 

Gunners not retire to one dugout or to one part of trench, so all 
will be struck by one shell. 

After bombardment, two men mount gun others remain under 
cover. 

When enemy attack is launched without covering machine gun 
and infantry rifle fire from the flanks, and when speed is especially 
important, undue attention is not paid to exposure. 
50 



MACHINE GUNS IN TRENCH WARFARE. 51 

Strong dugouta are provided near each niachine-gun emplace- 
ment for the men. 

Strong splinter-proof lookout posts are provided for use during 
a bombardment while the machine guns are in the dugouts. 

Three or four men are sufficient in front trenches remainder 
are kept in reserve trenches. 

During a bombardment by our artillery, machine guns should 
not be fired except at a very favorable target. 

AMMUNITION. 

Ammunition supply must be carefully thought out. 

British have 8 full belts and 4,000 rounds in unopened boxes with 
each gun. 

Other full belts, belt-filling machines, and 4,000 in unopened 
boxes with spare gunners at central depot in reserve trench, or other 
suitable place. 

Arrangements for filling belts or strips in dugouts or reserve 
trenches. 

In wet trenches care taken to keep belt boxes out of the mud. 

Belts and boxes kept in ammunition recesses clean and dry. 

Ammunition not kept all together in one place. 

Ammunition kept dry as possible and inspected daily. Each 
round turned to prevent sticking in belts. 

EMPLACEMENTS. 

One emplacement reserved for each machine gun as battle emplace- 
ment never used except to meet enemy attack. 

Several alternative emplacements are made one should be open 
for firing over the parapet. 

Every emplacement is numbered and marked and has a range card 

in it. 

Emplacements numbered from right to left in each brigade. 

After firing from one emplacement move gun quickly to another 
prevents location by artillery and is good practice. 

Firing from dummy emplacements will deceive enemy as to posi- 
tion of emplacements and to the number of guns. 

Emplacements and dugouts are always kept in good repair. 

In each emplacement limits to which machine gun may be trav- 
ersed with safety to friendly troops are marked with posts or sand- 
bags. 

When the machine-gun position is liable to be rushed due to weak 
wire entanglements, or if due to the closeness of the enemy trenches 
it is subject to attack by bombers, the guns are dismounted and kept 
in the 'dugouts during the daytime. 

Smoke helmets are worn when firing is kept up in bombproofs. 



52 MACHINE GUNS IN TRENCH! WARFARE. 

OVERHEAD FIRE. 

Our troops should be notified before firing over them. 

LAYING OUT TRENCHES. 

When trenches are dug deliberately, machine-gun positions are 
chosen first this enables trenches to be held with minimum number 
of riflemen. 

RELIEFS. 

Detachments relieved systematically to give officers and men 
sufficient rest. 

Three or four men in front trenches at one time and remainder in 
reserve at central dugout, or ammunition depot, will enable front- 
line men to be relieved every 24 hours. 

Units should be relieved every few days. 

Other troops assist machine-gun organizations in carrying ammuni- 
tion, revetting material, etc., when necessary. 

CONTROL OF GUNS. 

The machine-gun officer. 

Establishes himself at place where messages can always reach him. 

Keeps in touch with his guns and with the officers of the line of 
trenches he is assisting to defend. 

Arranges for fire control and direction usually in the trenches a 
man is placed in charge of each gun with definite instructions what 
to do in various eventualities. 

ENEMY MACHINE GUNS. 

Telescopes are of great value in spotting enemy machine guns, 
observation of fire, etc. Training of both officers and noncommis- 
sioned officers required to get best results from telescopes. 

If enemy machine guns located and doing no material damage, 
leave them alone. If fired on they will change position. If we 
know their location, when our attack is launched, our machine gun' 
can keep down their fire. 

CLEANING. 

J^fachine guns and all stores cleaned at least once daily. 

BRIGHT PARTS OF MACHINE GUNS. 

Painted khaki color to prevent reflection. 

PERISCOPES. 

Every one trained in their use. Never used near gun position but 
to the side. 

POSITIONS KNOWN TO ALL. 

Position of machine-gun commander of any section must be known 
to everybody. Every gunner must know the position of every gun 
whether it be in the front line, in the support trenches, in reserve, 
or in position in rear; also the best way to them. , 



MACHINE GUNS IN TRENCH WARFARE. 53 

TRAVERSING. 

The "Tap" traverse is the normal method. For sweeping para- 
pets and repelling rushes the "Swing" traverse is used. 

FIRING WITHOUT TRIPODS. 

Gunners should have practice in this. When emplacements are 
destroyed or tripods disabled, machine guns must he fired over the 
parapets, with only parapet rest. 

SHOVELS. 

In the attack a small shovel is strapped to the back of one gunner. 

OPENING FIRE. 

It is a point of honor for a machine gunner to always have his 
machine gun "tuned up " and ready for any emergency. 

VERY PISTOLS. 

Every machine gun has a Very pistol to show up enemy night 
attacks and to enable fire to be directed upon them. 

BOMBERS. 

Two or three bombers protect the machine gun during an attack; 
also when the opposing trenches are close together. This enables 
machine guns to be used to best advantage. All gunners receive 
instruction in bombing. 

ORDER BOARD. 

One in each emplacement. 

(Sample.) Order for sentinel and gun commander at No. 6 
gun position. 

Fire only to be opened by order of gun commander unless emer- 
gency arises, in which case sentinel uses his own initiative. 

When relieving another gun team or sentinel ascertain: 

Whether gun has been fired during the relief. 

If fired, what the target was. 

If fired, from which emplacement. 

The sentinel will inspect the gun before taking post. 

The sentinel will have accurate information of points on range 
card. 

In case of alarm or gas attack sentinel will wake gun team. 

The gun will not bo mounted, except during darkness, unless the 
situation makes it necessary. 

The gun will be cleaned daily, and weight of fusee spring noted 
both morning and night. 

Ammunition, spare parts, and hyposulphite solution will be in- 
spected daily. 

The lock spring (return or hammer) will never be left compressed. 



64 MACHINE GUNS IN TRENCH WARFARE. 

It is sufficient to half load and press the double button with the 
Vickers, or to place a magazine in position on the magazine post of 
the Lewis when mounting the gun at night. 

In order to meet an attack complete the loading. 
All dugouts, emplacements, ammunition chambers, etc., belonging 
to the gun position will be kept clean and in repair. 

Here follows any special orders of the position. 

MACHINE GUNS IN ENEMY GAS ATTACK. 

Gas affects working parts of a machine gun; also the cartridges in 
the belt. If long exposed, impossible to fire the gun. 

Gas is heavier than air sinks to bottom of trench or dugout. Guns 
in dugouts or low emplacements must be removed at once and placed 
to fire over the parapet. 

A sprayer is kept with each machine gun. 

There are two courses open to the machine-gun officer: 

1. To order fire to be opened with a view to 

Preventing the enemy leaving his trenches and keeping down 
their fire so as to enable his own troops to keep their heads high. 

Encouraging his own troops. 

Keeping his machine guns working, as, while in movement, the 
various parts are less affected by the gas and the firing of the machine 
gun has the effect of dispersing the surrounding gas to a certain extent. 

2. To reserve his fire, with a view to taking advantage of a careless 
advance on the part of the enemy following up their gas. In this 
event he should use his sprayer constantly. 

The course of action adopted will depend on the effect produced 
by the gas on the troops in his trench. 

. COMMUNICATION. 

Is difficult in defense, owing to the cutting of telephone wires. 

Is more difficult in attack, as enemy sometimes places a barrage of 
fire behind our troops after they have gone forward. 

For these reasons every form of communication must be used to 
maintain communication between machine guns in rear and on the 
flanks and the troops that they are supporting. 

Telephones. Connect brigade, battalion, company head- 
quarters, reserve dugouts, etc., with the guns, normally. The guns 
are also connected laterally. 

Orderlies. Machine-gun commanders and section commanders 
also have a sufficient number of well-trained orderlies attached 
beforehand. 

Visual signaling. Ah macnine gunners are trained in sema- 
ohore signaling. 



MACHINE GUNS IN TRENCH WARFARE. 85 

The best method of insuring success is: 

A carefully arranged plan of action. 

To have plan understood by all concerned. 

Definite orders to officers and machine-gun commanders. 

Then if communication breaks down the individual on the spot 
can do his best to insure the success of the general plan. 

The foregoing will guide machine-gun officers in choosing their 
own positions, which must vary according to the ground and to the 
tactical requirements of the situation. 

DEFENSE. 

For the defense of an entrenched line, machine guns of each 
section must be arranged by one officer. 

He allots areas to each gun. These must slightly overlap. 

Whole area allotted must be capable of being seen by gunner 
theoretical marking of lines of fire on map not sufficient. 

Trench map prepared showing position of each gun and area swept 
by it. 

Machine-gun commanders of adjacent brigades must confer as to 
their flank guns. 

Machine guns must cover areas that artillery can not reach or can 
reach with difficulty. 

Aim is to create belts of machine-gun fire across the front. 

Machine guns are so placed as to bring oblique or enfilade fire 
against: 

The enemy trenches. 

The ground over which he must pass should he attack. 

Our own front line trenches should enemy penetrate into them. 

To achieve these objects, machine guns may be placed: 

In a salient. 

In a reentrant. 

At a bend in the trench. 

In front of the trench. 

In or near support or communication trenches. 

In a straight portion of trench, firing through oblique loopholes. 

Emplacements some distance in front of the trench, concealed, 
and approached by a covered sap are useful both for attack and 
defense. 

Machine guns are, if possible, covered from fire from the front 
while being able to sweep the front of the entrenched line with 
cross-fire. 

While firing to the flank, its front is swept by the fire of the neigh- 
boring machine gun. 



56 MACHINE GUNS IN TRENCH WARFARE. 

Arrangements must be made so that machine guns may fire to the 
front should an emergency arise. To do this: 

Arrange so that some sandbags can be removed thus making a 
loophole to the front. 

Remember that 

If sandbags are left in position for considerable time without being 
moved, they may become embedded and be found immovable. 

Loopholes filled with single sacks will not be bullet proof. 

Train gunners to quickly remove the maching gun from the tripod 
and fire over the parapet, or to take gun and tripod and fire from some 
previously selected spot. These methods require practice. 

Machine guns should always be concealed from the front. 

DISTRIBUTION. 

In making the distribution of the machine guns, the following 
positions should be considered: 

In the front line trenches. In a stubborn defense they may 
just make the difference between success and failure. 

In or near support trenches. To prevent further advance of 
the enemy should they capture the front line, to enfilade the front 
line should it be captured, and to sweep communication trenches. 

In positions in rear. Should the ground be favorable they can 
be arranged to: 

Fire over trenches and sweep ground in front. 

Fire through gaps in the line. 

Command positions where the enemy can concentrate before 
attack. 

Command covered approaches to the defensive line. 

Command likely enemy machine-gun positions. 

Give overhead covering fire when our troops attack. 

Use indirect fire against ground in rear of the enemy's lines. 

In strong places just in rear. These positions should be strong 
and inconspicuous. They are arranged so that the ground in front 
is swept by cross-fire. 

Some in reserve. These are used for instructional purposes 
when not otherwise required. 

The number of guns placed in each of these divisions will depend 
upon the number of guns available, but emplacements should be pre- 
pared and arrangements made to place machine guns in any of these 
positions if they should be required. 

ATTACK. 

The Brigade Machine-gun Officer must be fully informed of the 
plan of operations as early as possible. 



MACHINE GUNS IN TRENCH WARFARE. 57 

He, in conjunction with the officers in command of sections, works 
out the detailed plan for the employment of the machine guns. 

The brigade machine-gun officer will 

Make a study of the enemy's front line and its relation to his own 
trenches. 

From a study of maps make himself acquainted with the ground 
in rear of the enemy front line, and also with his trench system. 
Aeroplane maps are required for this. 

Issue definite orders to officers commanding the different sec- 
tions, as to the employment of the guns, after approval of the higher 
commander. 

Make certain that machine-gun positions which he will require 
are in good condition. 

In this manner, each machine gun or group of guns will have a 
specific task. Before the action begins, all will know their duties. 

All machine guns must be in their allotted places before the 
preliminary bombardment commences. 

Machine guns are the weapons most likely to hold up the attack. 
Efforts must be made to locate enemy machine guns. Certain guns 
are detailed to engage these guns as soon as the bombardment ceases. 

Machine guns have definite tasks and must not be interfered with 
by other officers. 

Machine guns will be allotted: 

Some to go forward with the attacking infantry. The 
number will depend upon the front to be attacked and the nature 
of enemy's trenches. 

Their role will be to make good the ground gained by the infantry. 

They go forward when it is sure that the infantry is established 
in the captured trench. 

Teams conceal their identity as machine-gun teams, by mingling 
with a wave of the infantry, and carrying their guns inconspicuously. 

The approximate locality where each machine gun will be mounted 
in the captured line should be settled in advance. 

Lewis guns, or guns with light mountings, should be used for 
this work. The heavy tripod is brought forward after the position 
is consolidated. 

Some to cover the infantry advance. The positions of these 
guns will depend upon: 

The lie of the ground. 

The nature of the attack. 

The position of our own and the enemy's trenches. 



58 MACHINE GUNS IN TRENCH WARFARE. 

These machine guns are allotted as follows: 

Some to prevent the cross-fire by rifles and machine guns from 
the enemy's trenches situated on the flanks of the attack. 

Some to bring oblique or enfilade fire on to the portion of the 
enemy trenches being attacked. 

Some to sweep the ground over which the enemy's reserves may 
advance to the counter attack. 

Some may be pushed out in front of the line, to keep down enemy 
fire while the infantry are getting out of the trenches and through the 
wire. These latter may be in saps, crops, or folds of the ground. 

When the attacking infantry masks the fire of the machine guns, 
they should, if possible, direct their fire past the flanks of the attack- 
ing troops, so as to keep down flanking fire and prevent flank attacks. 

If our troops are required to lie down between the trenches, the 
machine guns try to keep down the fire of the enemy's rifles and 
machine guns. 

When their covering role is completed, the machine guns auto- 
matically return to the control of the brigade machine-gun officer, 
who will give further orders. 

Some in reserve under the brigade commander. These are 
retained as a real reserve, not pushed too early into the fight. 

From positions in rear they may be used to sweep ground behind 
the enemy's front line, fire against counter attacks, etc. 

SEPARATE PLANS. 

If the attack is to consist of two or more phases (two or more dis- 
tinct advances), separate plans must be made for each. 

AMMUNITION SUPPLY. 

Arrangements for ammunition supply, belt or strip filling, ammuni- 
tion depots, etc., are made before the action commences. An officer 
is placed in charge of these arrangements. 

POST OF BRIGADE MACHINE-GUN OFFICER. 

With or near the commander of the troops. He provides himself 
with a sufficient number of trained orderlies. 



MACHINE GUNS IN TRENCH WARFARE. 59 



auction of a Df ended Area 




Had-| 
quarteri. 

Self-siutalnbg strong p^Cnt, fln 
tn all direct 

Vj- i j^ 

\ / te ere s rallying yolat 



tion trench. 
Latrine. 
Dresln( station. 



Contain* uart*rs aad depot* JO* to 

40' underground. 



Sniper* *mplaceBt. 
Bowling arm. 



PLATE 1. 



60 MACHINE GUNS IN TRENCH WARFARE. 




PLATE 2. 




(.1 



62 



MACHINE GUNS IN TRENCH WARFARE. 



PLATE 4. 



TYPICAL 
SUPPORTING POINT 




PRCPARLOAT WMT AAJJ C.LE5t. FBCM LATC3T AVAJLAflLf INTOfiMATi 



MACHINE GUNS IN TKENCH WARFARE. 63 




PLATE 5. 



64 



MACHINE GUNS IN TRENCH WARFARE. 



PeUili- of_lrent_ 1 int trentli. 



Machine fun r nijr eplae> 
tntl In front of trnverte*. 



Barrow pit ttk. 
and (round wir 



ThU faco.lMld up Hill bftlkct work 
r with burlap and chlektn-lr 




Tin en with pebbles imide an hung on tht ir* to 
"regutr" thf ipproch of boiib throer at night* 




1 Machine guit". 
T- Traverse 

PLATE 6. 



MACHINE GUNS IN TRENCH WARFARE. 



65 




17 5 



66 



MACHINE GUNS IN TRENCH WARFARE. 




MACHINE GUNS IN TRENCH WARFARE. 



67 




BOMB PROOF M.C. 
- EMPLACEMENT 

BIGHT * U FLAMK. 
OPCH tMPtACIMINT 
reOHTAt HM AHO 

SMJNTU poor 

WOK-OUT POST. 



ftlCHT M.C EMV 
WITN LOOK-OUT 
POST . SAP 

COVtRIMC REMOVE 




PLATE 9. 



68 MACHINE GUNS IN TRENCH WARFARE. 




-., ISilfi 

// ggjsifc 

111 8^ 



MACHINE GUNS IN TRENCH WARFARE. 



69 




HIDDEN M.G 
EMPLACEMENT 
.AT CROSS -ROADS 
IN .A VILLAGE 
PREPARED 
FOR PEFE.NCE 





L 



^A!^ 





PLATE 11. 



70 MACHINE GUNS IN TRENCH WARFARE. 



RECTANGULAR LOOP-HOLE 



INSIDE DIMENSIONS 




THIS IS STRONGLY MADE OF Z' PLANKS TO SUPPORT WtlGHT OF SANDBAGS ON 
TOP. SLIDING STttL PLATES CAKK ARRAN6ED AS IN OTHER LOOP-MOU.AM) ALSO A LI6HT 
DINGED DOOR rORBLIISDING. 





LOOP-HOLE BOX. 
A A. FIXEP STEEL PLATES ON END. . 



>. STEEL SLJWTSC DOOR, ARRANGED TO 
SLIDE TO RIGHT. [THIS MYM MAM IN TWO MUTTS 

TO SLIM KICHT AND LtFT.^ 

C.C. BATTENS TO MAKE SLIDE FOR DOOR 



PLATE 12. 



MACHINE GUNS IN TRENCH WARFARE. 



71 




RANGE CARDS. 



DEFENSE. 

(a) Thick line first to reference point as "orienting line." 
(6) Lines correct relative length. 

(c) Range from one flank to the other in order. 

(d) Mark lines accurately. 

(e) Describe points briefly and accurately. 
(/) Describe exact point from whence taken. 
(g) All names in block letters. 




Emplacement No. 6. Midway between old barn on right and small 

tree on left. 
72 



MACHINE GUNS IN TRENCH WARFARE. 73 


ATTACK. 

(a) First take range to objective, then halfway point, then inter- 
mediate objects. 
(6) Put ranges in right-hand column. 

(c) Objects must be in line of advance and likely to be easily 
recognized when reached. 

(d) If possible, objective should be visible from each point taken. 

(e) Fill in left column with range from objective and rule through 
right column. 



600 
1DOO 

1450 
2000 



1st objective Ridge 



of 



Gate 
Rendezvous. 



JOOO. 



551. 



PLATE 14. 



74 



MACHINE GUNS IN TRENCH WARFARE. 



The graticule card. 

[To be held 18" from eye.] 

FOR MARK VI AMMUNITION. 



-200 



600 



-400 



-1000 



-800 

9 

-1200 



-1400 



-1600 



-1800 



300- 




2000 



1500 



1900 



The machine gunner's range and trajectory card with angles of elevation 
etc., for Mark VI ammunition. 









Culmi- 


Range. 


Approxi- 
mate 
angles of 


Rise in 
minutes. 


nating 
point of 
trajec- 




elevation. 




tory in 








feet. 


Yards. 


, 






100 


10 




... 


200 


14 


~7 




300 


21 


6 


"i" 


400 


27 


8 


2 


500 


35 


9 


u 


600 


44 


13 


6 


700 


56 


13 


9 


800 


1 10 


12 


13 


900 


1 23 


15 


17* 


1,000 


1 38 


15 


23i 


1,100 


1 53 


16 


31J 


1,200 


2 11 


18 


41 


1,300 


2 28 


20 


52 


1,400 


2 49 


20 


66 


1,500 


3 9 


21 


82 


1,600 


3 30 


25 


100 


1,700 


3 55 


25 


122 


1,800 


4 22 


28 


146 


1,900 


4 50 


29 


174 


2,000 


5 20 


32 


206 


2,100 


5 53 


37 


241 


2,200 


6 29 


38 


282 


2,300 


7 11 


47 


325 


2,400 


7 57 


47 


374 


2,500 


8 46 


52 


429 


2,600 


9 39 


55 


489 


2,700 


10 37 


59 


558 


2,800 


11 37 


62 


637 


2,900 


12 41 




... 



MACHINE GUNS IN TRENCH WARFARE. 



75 



Trajectory disks, illustrating the cone of fire as it will appear in over- 
head fire, etc., for Mark VI ammunition. 



Range. 


Diameter of disks. 


Height of center of disk above 
ground, muzzle of gun is 
taken as being 20 inches 
above ground. 


75 per 
cent 
cone. 


100 per 
cent 
cone. 


700 yards 
tra- 
jectory. 


800 yards 
tra- 
jectory. 


900 yards 
tra- 
jectory. 


Yards. 
100 
200 
300 
400 
500 
600 
700 
800 
1,000 
1,500 
2,000 


Ft. ing. 
8J 
1 3J 
2 
2 SJ 
3 6 
4 
4 6 
5 6 
6 8 
10 
13 4 


Ft. ins. 
2 
3 6 
5 
6 6 
8 
10 
12 
14 
16 
24 
32 


Ft. ins. 
5 5 
8 6 
10 2 
10 7 
9 4 
5 11 


Ft. ins. 
6 5 
10 6 
13 4 
14 8 
14 2 
12 1 
7 6 


Ft. ins. 
8 Si 
12 10 
16 10 
19 6 
20 2 
19 
15 6 
9 1 





















DEPTH OF ZONE BEATEN BY 75 PER CENT OF SHOTS FIKED FROM A 
MAXIM GUN. 





Dispersion of cone. 




Depth. 


Width. 


Yards. 


Yards. 


Feet. 


500 


150 


4 


1,000 


70 


8 


1,500 


60 


13 


2,000 


50 


19 



PROBABLE ERRORS IN RANGING TO BE ALLOWED FOR WHEN 
DIRECTING FIRE. 



Method of ranging. 


Per 
cent of 
error. 


Extent of ground to be searched 
to overcome probable errors 
in ranging. 


500 

yards. 


1,000 
yards. 


1,500 
yards. 


2,000 
yards. 


Judging distance 
Judging distance com- 
bined with "key 
ranges" 


15 

10 
5 


Yards. 
150 

100 
50 


Yards. 
300 

200 
100 


Yards. 
450 

300 
150 


Yards. 
600 

400 
200 


Range-finding instru- 
ments 





76 



MACHINE GUNS IN TRENCH WARFARE. 



The graticule card. 

[To be held 18" from eye.] 

FOR MARK VII AMMUNITION. 



-1000 



1200 



-1400 



-1600 



-1800 _ 



2000 



1100 



1500 



1900 



Mark VII ammunition. 



Angles of elevation. 


Angle of 
descent. 


Cul- 
mi- 

nat- 
ing 
point. 


Trajectory 
disk. 


Low- 
est 
shot 
100 
per 
cent 
cone 
below 
cen- 
ter of 
disk. 


Height of center of 
disk above 
ground. 


Verti- 
cal. 


Hori- 
zon- 
tal. 


700 
yards. 


800 

yards. 


900 
yards. 


100 yards. . . 12 5 
200 yards. . . 15 
300 yards. . . 18 5 
400 yards. . . 22 5 
500 yards. . . 27 
600 yards. . . 32 5 
700 yards. . . 38 5 
800 yards. . . 46 
900vards. . . 54 
1,000 yards. .135 
1 1,100 yards. . 1 14 5 
1,200 yards. . 1 27 
1,300 yards. . 1 41 
1,400 yards. . 1 57 
1,500 yards. . 2 15 
1,600 yards. . 2 35 
1,700 yards. . 2 58 
1,800 yards. . 3 23 5 
1,900 yards. . 3 52 
2,000 yards. . 4 24 




.Feet. 














11 
1 10 
2 9 
3 8 
4 8 
5 7 
6 7 
7 6 


6 
1 
1 6 
2 
2 6 
3 
3 6 
4 


1 1 
2 2 
3 3 
4 4 
5 5 
6 6 
7 7 
8 8 


3 5 
5 8 
6 9 
6 11 
5 11 
3 10 


4 3 
7 2 
9 1 
9 10 
9 8 
8 2 
5 1 


5 
8 11 
11 4 
13 2 
13 9 
13 2 
10 10 
6 7 








0.6 
1.3 
2.3 
3.8 
6.1 
8.9 
12.8 
17.8 
24.1 
32.4 
42 
54 
69 
87 
108 
132 
161 
195 


lin 300 
1 in 180 
lin 120 
lin 90 
lin 67 
lin 50 
lin 40 
lin 30 
lin 24 
lin 20 
1 in 15 
lin 13 
lin 11 
lin 9 
lin 8 
lin 7 
lin 6 






Heights ofti 

At 100 yar 
At 200 yar 
At 300 yar 
At 400 yar 
At 500 yar 
At 600 yar 
At 700 yar 


ajectories above line ofsiglit 
at 800 yards. 

ds... ..29 


ds . 57 


ds 7 6 


ds .88 


ds 8 9 


ds 7 6 


ds 4 8 




75% zones: 500 yards, ?* y , d! 

yards, iiyd?- ; 1,500 yards, 
5 


:; 1,000 


10' 



MACHINE GUNS IN TRENCH WARFARE. 77 

Measurements of the 75 per cent cone, Mark VII ammunition. 



Range. 


Vertical 
diameter. 


Hori- 
zontal 
diameter. 


Depth 
of E. B. 
zone. 




Feet. 


Feet. 


Yards. 


500 


5 


2* 


220 


800 


8 


4 


172 


1,000 


10 


5 


140 


1,200 


12 


7 


112 


1,500 


15 


10 


70 



OVERHEAD FIRE. 
(a) String and Card Method of Overhead Fire. 

* 

"tvv.-" "iffETV ANCLE ., 



TRENCH 




SUPPORTED TROOPS 

Safe to fire overhead until troops reach "A.' 



(B)TMCEHT SIGHT METHOD 



ENEMY 800X 




AimnyM** 

focGunnm 

Sight raised 400" to give safety angle of 30 minutes shown by dotted line . 



o 



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