Trenches
... Soon after, the allies began to dig their own trenches and, therefore, trench warfare began. Not very long, after the first trenches of the war were dug, a network of trenches arose. ... Within the network, there were three different types of trenches: front line trenches, support trenches, and reserve trenches. The first line of trenches was called front line trenches. ... Between the trenches of opposing forces laid no mans land. This area between the opposing front line trenches was filled with barbwire and mines to prevent enemy crossing. ... The second and third types of trenches were the support and reserve trenches, respectively.