TRENCH WARFARE. Like every thing else in military affairs, the use of the trench received a great development during the recent great war. Under the old conditions the trench was simply an excavation in the ground long or short, broad or narrow, the earth from which was thrown directly in front to form a barricade. The trench might be a tem porary affair or it might be an element in a permanent and extensive fortifica tion. They could play a part both in attack and defense. The dimensions of a trench, and its intricacy or simplicity, would naturally be determined largely by the length of time it was intended to use it. Troops kneeling would require a depth that would leave them space to see over the parapet. Men standing would require greater depth that para pets might be cut at the sides to stand on if greater depth was needed for pro tection. In the hastily dug trenches proper for soldiers engaged in attack ing a depth of a couple of feet would be ample. The soldier lying prone would necessarily only hold the trench till he was enabled to advance still further.
In the development of military service that preceded the great war military en gineers had long spoken of the value of the trench and the part it was likely to play in future warfare. In every European army, the troops, apart from the engineering units, had been taught to construct trenches of established types. It was foreseen that in modern warfare large armies would confront each other for long periods with their ends resting on the mountains and the sea and that opposing lines would be paral lel to each other long distances and for indefinite periods. The idea then was to maintain the front line at a depth suit able for standing, with room for the coming and going of a single file of sol diers. Arrangements on the top of the trench would help the soldier to find shel ter and at the same time watch the en emy and hit him if possible. The faces of the trench were held firmly in a per pendicular position by planks, or sacks of earth. The spaces in front of the trenches were cleared so as to leave an unobstructed view, and obstructive bar riers, such as barbed wire, were placed in positions where it was expected that the enemy might attack. All these methods received great development during the world war.
As the war progressed, and it was seen that the troops might continue to confront each other in almost the same positions for months and even for years, trench warfare naturally assumed pro portions not before conceived of. The simple parallel lines of no great depth that had been the rule and theory hither to were transformed into complicated designs that increased in depth, in varie ty, and in intricacy according to the con ditions in a particular district. The
line sank into subterranean passages and broadened into large covered areas with divisions for resting, eating, diversion, and sleeping. Attention had to be paid to the draining in swampy districts, and where the danger was great fortifica tions built of concrete and of great strength were built up. The simple straight or curving line was in many places transformed into a zigzag or laybrinth pattern, and communicating trenches connected the front trenches with those behind and these again with the forces at the rear. The war took on the character of mutual siege con ditions, and this was largely due to the grip on the ground developed by trench work. The single trench line that proved so hard to capture in the Civil War of the United States grew into an elabo rate network of trenches deep below the surface and forming part of great plans covering large areas in the rear. A trench defended by barbed wire proved a difficult position to attack, and the great multiplication of machine guns, which the Germans provided as one of the great surprises of the war, made a position thus doubly protected almost impenetrable. An enormous expenditure of projectiles was found necessary to prepare the way for an attack that might result in the capture of two or three front lines. This it was calculated that preceding one such attack a French battery, near Arras, sent into the Ger man lines more projectiles than the en tire German artillery in the war of 1870 1871. Yet this tremendous fire was a nec essary preliminary, if the barbed wire was to be cut, the machine guns destroyed and the trenches leveled. The arrival of the tank, which was in effect an armored motor car and military tractor, able to cross trenches and shell craters, proof against machine gun and rifle fire, and itself armed with machine guns, solved a problem that had hitherto been baf fling. Nevertheless the trench showed itself capable of developments that are sure to affect all future warfare. Trenches, under the development of war fare, may be dug to any depth, may be expanded to any breadth, may be di vided and designed on any pattern, and may be re-enforced to any extent condi tions may warrant. In view of the great part aeronautics are likely to play in the future warfare, the roof of the trench is likely to be a matter of im mense importance, and trenches that lead to underground cities are not an impos sible conception. Under the circum stances it was only in the nature of things that the mining of trenches was one of the great occupations of the war and approaches were made in that man ner which would have been impossible overground.