When the battle of the Marne commenced and the British and the French drove forward, this valuable lesson and many others had been learned, so that when the armies had reached the limits of their endurance, instead of digging themselves in in the old style, a new system was used, greatly assisted by shell fire. A round hole was dug by each man to fit his individual size and made to suit himself. Here he squatted and fought, if necessary, and got what rest was possible during that day, with the enemies’ line at distances varying from 100 to 500 yards from him. During the night, these men when not fighting or bothered by counter-attacks, or trying to obtain rations, water and the many necessaries that a fighting man requires, deepened their shelters and joined them together by little narrow ditches. During the next day there might be bitter fighting, so it would be even possible that other troops would come up and relieve during the early dusk. The relieved troops would retire a short distance and dig themselves another row of little holes where they might act as supports in case the temporary front line gave. During that night the holes on the front line would be enlarged until they finally joined and gradually without deliberate intention the trench became a permanent feature. Then the line slightly in the rear became connected with the front line system by what were then nothing more or less than ditches and this was the birth of the present system which now stretches from the sea to Switzerland. The trench systems now generally consist of three complete lines or systems of trenches, each system being self-supporting and independent of the other. The second and third systems are generally laid with due consideration to protection, fields of fire, and all the other tactical requirements that are necessary to such a system; it being impossible in the majority of cases to keep these points in mind during the building of the first or original line. These systems generally run to a depth of six to eight miles from the front firing line. They are so constructed that when a firing line has been broken through to any great extent, what was formerly a communication trench at once becomes a fire trench, and serves to bring a heavy enfilade fire on the troops occupying the captured area. It must be remembered that the considerations, arguments, and notes laid down in this book cannot, under stress of circumstances, always be acted on. It will be found, however, that a certain amount of training and of study as to the conditions governing the sighting, building, and living in these trenches, will cause a man, even under great stress of excitement, to look for and try to obtain the ideal as a matter of habit and without giving much time and thought to the question. The Art of War is “the greatest amount of common sense used in the shortest possible time.” J. S. S. EDITOR’S NOTE