The Entente Offensive, Autumn, 1916 thened by trench-mortars and bomlr-throwers. The supply of all quick-loading weapons had to be increased. Lastly, the formation of storm troops from the infantry, which had begun during the war, had not only to be regularized, but to be adapted to the common good. The Instruction Formations and the storm battalions had proved their high value both intrinsically and for the improvement of the infantry generally. They were examples to be imitated by the other men. But for this it was necessary to have a training manual prepared and this had not yet been done. The course of the Somme battle had also supplied important lessons with respect to the construction and plan of our lines. The very deep underground forts in the front trenches had to be replaced by shallower constructions. Concrete " pill-boxes/1 which, however, unfortunately took long to build, had acquired an increasing value. The conspicuous lines of trenches, which appeared as sharp lines on every aerial photograph, supplied far too good a target for the enemy artillery. The whole system of defence had to be made broader and looser and better adapted to the ground. The large, thick barriers of wire, -pleasant as they were when there was little doing, were no longer a protection. They withered under the enemy barrage. Light strands of wire, difficult to see, were much more useful. Forward infantry positions with a wide field of fire were easily seen by the enemy. They could be destroyed by the artillery of the enemy, and were very difficult to protect by our own artillery. Positions further back with a narrower field of fire and more under the protection of our own guns were retained. They were of special service in big actions. The decisive value of artillery observation and the consequent necessity of paying great attention to the selection of positions had also become apparent. Here also there was much to be done ; so much had changed, so much become completely transformed. At the conference in Cambrai these various matters were merely touched on. I got no more than general impressions, but these were enough to show the necessity of altering the plan 373 18