The History of Trench warfare
In World War I, both sides constructed elaborate trench and dugout systems opposing each other along a front protected from assault barbed wire . The area between opposing trench lines also known as "no man's land" was fully exposed to artillery fire from both sides. Trench warfare is a form of land warfare using occupied fighting lines consisting largely of trenches, in which troops are significantly protected from the enemy's small arms fire and are substantially sheltered from artillery. Trenches were usually about 12 ft. deep. They were never straight but were dug in a zigzagging or stepped pattern. During the day, snipers and artillery observers in balloons made movement perilous, so the trenches were mostly quiet. Consequently, trenches were busiest at night, when cover of darkness allowed the movement of troops and supplies, the maintenance and expansion of the barbed wire and trench system, and reconnaissance of the enemy's defences. Sentries in listening posts out in no man's land would try to detect enemy patrols and working parties or indications that an attack was being prepared. Trenches usually were equipped with mortars and light machine guns to stop the enemy from advancing.