Trench warfare
Components

The banked earth on the lip of the trench facing the enemy was called the parapet and had a fire step. The embanked rear lip of the trench was called the parados, which protected the soldier's back from shells falling behind the trench. The sides of the trench were often revetted with sandbags, wire mesh, wooden frames and sometimes roofs. The floor of the trench was usually covered by wooden duckboards. In later designs the floor might be raised on a wooden frame to provide a drainage channel underneath. Due to the substantial casualties taken from indirect fire, some trenches were reinforced with corrugated metal roofs over the top as an improvised defence from shrapnel.

The static movement of trench warfare and a need for protection from snipers created a requirement for loopholes both for discharging firearms and for observation. Often a steel plate was used with a "keyhole", which had a rotating piece to cover the loophole when not in use. German snipers used armour-piercing bullets that allowed them to penetrate loopholes. Another means to see over the parapet was the trench periscope – in its simplest form, just a stick with two angled pieces of mirror at the top and bottom. A number of armies made use of the periscope rifle, which enabled soldiers to snipe at the enemy without exposing themselves over the parapet, although at the cost of reduced shooting accuracy. The device is most associated with Australian and New Zealand troops at Gallipoli, where the Turks held the high ground.

Dugouts of varying degrees of comfort were built in the rear of the support trench. British dugouts were usually 2.5 to 5 m (8 to 16 ft) deep. The Germans, who had based their knowledge on studies of the Russo-Japanese War, made something of a science out of designing and constructing defensive works. They used reinforced concrete to construct deep, shell-proof, ventilated dugouts, as well as strategic strongpoints. German dugouts were typically much deeper, usually a minimum of 4 m (12 ft) deep and sometimes dug three stories down, with concrete staircases to reach the upper levels.
change_case:english_lowercase