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Full text of "The history and construction of Fort Dupont / thesis prepared by Richard Francis Lane"

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Thesis Prepared by 
Richard Francis Lane 

Presented to Maryland Beta Chapter of 
Tau Beta Pi 
January IS, 1934 



The information for this thesis was obtained from the 

following sources I 

"The Defenses of Washington lS6l-lgo5," 
by John K. Wilson. 

"The Defenses of Washington," 

by William Van Zandt Cox. 

"The Defenses of Washington , " 

by Major General John G. Barnard. 

"Centennial History of Washington, D.C.," 
by Crew. 

Interview with Mr. Fosaffy, Chief of Old Record Division 
of Adjutant General's office of the War Department. 

"Official Records of the Rebellion," 

Vol. 19, Series 1, Part 2. 

Official Records of Engineer Corps, U. S. Army. 

"Rambling Through Washington, ■ 

by T. D. Satchel. 

Files of Evening Star. 

Division of National parks, Buildings, and Reservations, 

Department of the Interior. 




At the beginning of the Civil Wax in April of lS6l , the 
defenses of Washington were still as inadequate as they had been 
when the nation's capital had been captured by the British. In 
order to remedy the situation a system of 62 forts was built on 
the heights around the city with a perimeter of thirty- five miles, 
Fort Dupont was one of this system of forts and was located on 
the heights overlooking the Anacostia river and commanding the 
Navy Yard. Built late in 126 1, it was subsequently improved late 
in 1862 under the direction of Major General Barnard under the 
Secretary of War, Stanton. 

Fort Dupont was built in the form of a regular hexagon of 
100 feet on a side inside giving it an inside perimeter of 200 
yards. First equipped with only six guns, the armament was later 
increased to nine guns. A magazine was provided in the center of 
the fort for 100 rounds of ammunition for each gun. 

Some time after the war the land occupied by the fort was 
purchased by the government. Then on August 10, 1933, it was 
transferred to the jurisdiction of the Department of the Interior, 
It is now well kept and used as the District tree nursery. 




When the national capital was captured by the British in 

181 1 ! after the battle of Bladen sburg it had no defenses except 
a very few hastily thrown up earthworks and the surrounding hills, 
which George Washington had called natural defensive features at 
the time he was President of the United States. After the war 
was over substantially nothing was done in the way of fortifying 
the city of Washington, in spite of the previous disastrous 
occurrence, up to the time Fort Sumter was fired upon in April, 
lS6l . According to Major General J. G. Barnard, who later was in 
charge of the defenses of Washington, our own engineer officers 
at the beginning of the war knew less about' our capital than they 
did of the historic aporoaches and fortifications of Paris and 
other important European capitals. The first serious attempts 
at further fortifications for the city were quickly improvised 
earthworks thrown up on the Virginia side of the Potomac by three 
Army engineers with untrained men who set out from Washington by 
night to secure a Union foothold at the three main routes out of 
Washington to the South in the State of Virginia, which had just 
seceded from the Union in April of lS6l. 

Late in the summer of lS6l General Mansfield, assisted by 
Major H. G. Wright acting as a volunteer, began construction of 
a system of forts to guard approaches and roads leading to the 
capital. This was deemed expedient at that time since Washington 
could easily have been taken by the rebel soldiers after the 
battle of Bull Run in July if they had not been too demoralized 


by their victory to follow it up. It was no easy task to fortify 
Washington since it had grown from its rather compact state in 
Washington's time to a widely scattered community. Also the low 
hills, which had seemed good natural defensive features to General 
Washington, had now turned into a possible threat, since the newly 
developed artillery with its longer range made it possible for 
enemy batteries, if located on the heights surrounding Washington, 
to fire easily on the White House, the Capitol, and other important 
government buildings. Therefore a string of forts waB laid out and 
construction begun on them. This string of forts, which had a 
total perimeter of thirty-five miles, circumscribed Washington more 
or less on the summit of the hills and commanded the important 
approaches. Construction of these forts was very much hampered by 
the clause in the Congressional appropriation bill disallowing any 
expenditures for new fortifications. Hence the few old works had 
to be improved as much as possible, but since the safety of the 
capital was considered paramount, land for new fort and battery 
sites was seized and the timber required for building obtained by 
cleaning the land for the forts. 

South of the Anacostia river, commonly known as the "Eastern 
Branch, the heights not only commanded the government buildings 
but also the Washington Arsenal where vast stores of ammunition 
were kept, the Navy Yard, and the only two bridges across the 
Anacostia, Bennings bridge and the one at the Navy Yard. These 
heights consisted of a series of contorted ridges, cut by numerous 
ravines at all angles, located between Oxen Fun, now called Oxon 
Run, which flows into the lower Potomac, and the Anacostia river. 


In order to prevent occupation of these ridges by the enemy, six 
forts along these heights were planned. Construction was started 
late in September of lS6l and the forts were practically finished 
by the end of the year. Fort Dupont was one of the smaller of 
these fortB and was probably so called after Admiral Dupont who 
had just been a prominent figure at Charlestown as commandant of 
the Atlantic Blockading Squadron. Located on a hill J00 feet 
above the Anacostia river, Fort Dupont was in the District of 
Columbia about one-fourth mile from the District line and near 
what is now Capitol Heights, Md. It, with the other forts of the 
system, remained as they were built until in 1262. Then the new 
Secretary of War, Stanton, realizing that the defenses of Washing- 
ton were inadequate, assumed full responsibility for the expendi- 
ture of money to improve and strengthen the capital's defenses. 
Therefore, on October 25, 1S62, he appointed a committee of the 
most important engineer officers of the United States Army to 
look into the situation. 

Brevet Major General J. G-. Barnard, distinguished scientist 
and engineer, was made chief engineer in charge of the defenses 
of Washington. In the report of the committee of which he was a 
prominent member, he stated that the forts and batteries built 
around Washington were merely detached earthworks which lacked 
communication facilities or unity. Also he observed that the 
buildings, magazines, and bombproof s had been constructed after 
text-book designs which had been superseded by new designs based 
on practical experience. He recommended a number of changes in 
the system of forts in order to strengthen them and repla.ce the 


de signs which had been found faulty. In regard to the six forts 
on the ridges overlooking the Anacostia river, he said that the 
works were too widely separated and therefore could not cover a 
number of ravines which wei e invisible from these forts. In 
order to remedy this situation, the General recommended that 
batteries be placed between the forts and that an outwork be 
placed east of Fort Meigs,, which were, in his own words "to form 
with Fort Dupont a congeries of works or forts which can be con- 
sidered as a single fortification or fortified camp, which shall 
sustain and flank each other and, from numerous points of view, 
see and guard all ravines and otherwise hidden surfaces." These 
forts thus beca,me a number of strong groups of works somewhat 
isolated from each other which had however been laid out originally 
with the idea of a line in mind. Previous to the appointment of 
the committee, General Barnard had recommended to General D. P. 
Woodbury, who was in command of the works on the Eastern Branch, 
that these works , which were regarded as holding points from which 
the city might be shelled, should be provided with several days 
provisions and a garrison kept inside each fort at all times. He 
further advised General Woodbury to distribute the field guns 
from Fort Baker to Fort Dupont, Fort Meigs and Fort Davis. 



Fort Dupont was shaped in the form of a regular hexagon of 
100 feet on each side, thus giving it an interior perimeter of 
600 feet or 200 yards. The front of the fort was one side of the 
hexagon and faced almost due south but a little to the east. 
Around the entire fort was 'a ditch about S feet deep and 10 feet 
wide at the bottom. Just inside this ditch a parapet was thrown 
up with the earth from the ditch and covered thickly with sod. 
The outer half of the parapet , that is the part nearest the ditch, 
had a slope of ^5 degrees while the remainder of the parapet, 
having the horizontal thickness of 10 feet as the front part, 
had a slope of about 15 degrees. The inside of the parapet was 
almost vertical, thus giving the parapet a total thickness at its 
base of 20 feet. Outside of the ditch, a glacis of earth was 
thrown up for about 30 feet from the ditch in order to bring the 
ground in front of the fort in the plane of fire from the fort. 
The slope of the glacis was the same as the top of the parapet 
which was 9 feet high from the ground inside the fort to the very 
too of the parapet. Aoproxlmately 35 feet from the ditch, an ■ 
abatis was constructed from large trees with their sharpened 
branches pointing outward and the bases of the trunks resting 
against vertical posts and timbers driven in the ground. The 
parapet was pierced for embrasures at each corner of the hexagon, 
and in six places on the three forward sides of the fort. Access 
to the fort was over a log bridge crossing the ditch and then 
through a timbered opening in the parapet. Heavy log gates were 
used to close the opening in the parapet. Inside the parapet 
raised platforms were built for the ?uns and runways were made 


to reach the platforms. The embrasures for the guns were made in 
the "oaraoet by using vertical logs about 12 inches in diameter to 
retain the earth and protect the gunners. The gun platforms were 
made of wood and arranged so that the guns could be swiveled around 
to cover about 100 degrees of horizontal fire. 

Originally, six guns were installed with embrasures for six 
more, but later the armament was increased to nine guns with space 
for six field guns. The final armament of the fort consisted of 
three g-inch siege howitzers, three 2*l-pounders, two 6-inch field 
guns and one 2^— pound mortar. 

In the center of the fort, a large magazine ko feet by 90 
feet was constructed capable of holding 100 rounds of ammunition 
for each gun. The magazine consisted of two timbered rooms, one 
lower than the other, and both partly sunk in the earth floor of 
the fort and then covered with a thick layer of earth and finally 
sod so that the earth cover on any point was at least 10 feet 
thick. This thickness of 10 feet was found, according to Major 
General Barnard, "to be very satisfactory after extensive tests 
with short and long range artillery fire." Entrance to the magazine 
was at the rear. The details of the interior construction of the 
magazine are very interesting and show the thoroughness with which 
the powder stores were safeguarded. The side posts of the interior 
of the magazine were vertical and at least 12 inches in diameter. 
They were usually of hard wood such as oak., chestnut, or cedar. 
The roof logs also were at least 12 inches in diameter and wer° 
so hewn as to fit tightly together. Around the outside vertical 
walls inclined roof supports & inches in diameter were placed with 


the ends cut at an angle so as to butt against the roof logs. 
Outside on these inclined supports, a revetment of small oolee 
was placed. Thus a protective air space was provided all around 
the magazine and additional support for the roof provided since 
it had to sustain the enormous weight of earth placed upon it. 

In regard to the details of the waterproof roof construction 
General Barnard's description of the construction used in all of 
these forts can not be improved upon. "Above the roof logs was 
placed along the longitudinal center of the magazine a log not 
less than 12 inches in diameter and parallel with it smaller logs 
spaced 2^- inches from center to oenter. These were so hewn as to 
correspond to superior faces or slopes, having an inclination of 
one upon four. The earth was then thrown on and rammed completely, 
flush with the upper surfaces of these hewn purlines. Upon these 
were nailed, first a course of 1-lnch plank, tongued and grooved 
and painted on the under side with a composition, applied while hot, 
of coal tar and resin boiled together. A heavier composition of 
coal tar, resin, and sand was used to flush the joints as they 
were driven home. The upper side of this roofing course was then 
painted thickly with the composition, after which was applied 
another course of 1-inch pine boards nailed to the previous course 
of oak plank. Great care was necessary in the laying of this 
roofing, so as to leave no opening through which water might pene- 
trate. The second course was laid simultaneously with the applica- 
tion of the hot composition to the upper side of the oak boards. 
A strip of oak roofing, not more than one foot in width, was 
covered with the hot composition applied with a swab or mop of old 


ca.nva8 and a board of the second course Immediately followed, 
being worked into the composition by two or three longitudinal 
motions of the hands of the workmen. After the second course 
was nailed down, another coating of tar was applied, covering 
every portion of the surface and flushing the joints. Two or 
three inches of fine clean sand was then thrown on, followed by 
about two feet of clay applied in layers of 6 to S inches, then 
thoroughly rammed. The remainder of the earth covering was then 
thrown on and compacted sufficiently to preserve the proper slopes, 
the whole being covered with sod laid on superficially where the 
angle of the slope would permit." The magazine was well drained, 
since its floor level was above the bottom of the ditch which 
furnished drainage for the whole fort, and well ventilated by the 
air space around the magazine. In order to lighten the interior 
of the magazine and improve the air inside, the interior was 
whitewashed. The following drawings show the layout and construc- 
tion somewhat more clearly. 



Sketch -from or'J/nul /oJe»t-i 
Transi erfed. -frosn Of-f'/cm of 
Chief E'n^r. 3>e. fens es « f Wash, 
f6£nar. 3'e,pf. >h J<*n. /Si>i> 

/f, f. Lane 
J)dc2 9 t St J 3 


Cons tructi'oh Fea fares of Fort J) upon f. 

• of Secfrah, A~Q 


Scott o t> Vi&w o-f M<Ko<LT.ine 

SfceT^kts from 

ft F; Lane 


Some time after the war, the land which Fort Dupont occupies 
was purchased by the Federal Government and placed under the direc- 
tion of the Director of Public Buildings and Public Parks. On 
August 10, 1933 > fey executive order of the President of the 
United States, the property was transferred to the Department of 
the Interior under the jurisdiction of the Division of National 
parks, Buildings, and Reservations. 

During 1923 there was proposed a boulevard joining all the 
old Civil War forts and running past Fort Dupont but the plan did 
not go through. At the present time Alabama Avenue runs past the 
old Fort Dupont. 

At the present time the grounds around Fort Dupont are very 
well kept up and the property is used as the District tree nursery. 
The old earthworks are still standing and the hexagonal outline of 
the fort is easily discernible. The parapets are somewhat rounded 
and eroded but the openings for the embrasures are still very plair. 
All that remains of the magazine is a long rectangular mound of 
earth about 10 feet high and sunk along the top to a depth of 
about k- feet where the interior of the magazine collapsed after 
the timbers had rotted out. The ditch is still in good condition 
although the bottom has been somewhat eroded by water. 


Below - View showing east 
half of Interior of fort 
looking north with em- 
brasure at northeast corner 
in background. 


ft? *■%& 



Above - View of west 
half of interior of fort 
looking north, showing 
embrasure and old run- 
way in background. 



•• * «£ 


Below - View of front 
of old powder magazine 
showing how earth has 
caved in# 


Above - Another view 
of old powder magazine 
looking northeast. 


CloBe-up view showing 
details of inclined run- 
way to east side of fort. 



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