Soldiers equipped with entrenching tools can quickly construct a network of foxholes and trenches. The foxholes can be linked together with shallow crawl trenches and dug deeper to accommodate standing men. The parapets of trenches are constructed from soil that has been dug out. Duckboards line the trench's mucky floor, and a fire step serves as a makeshift firing platform. Modern trench warfare can be traced back to Sébastien Le Prestre de Vauban's strategy of progressively bigger trenches for stronghold attacks in the 17th century. Before the American Civil War, when both sides were armed with small arms and cannons, trenches were only utilized in siegecraft (1861–65).

From Belgium to northern France and Switzerland, millions of soldiers fought in trenches throughout World War I. (1914–18). Due to the constant threat of gunfire and shelling, soldiers were forced to take cover underground. The trenches of World War I consisted of many parallel lines, some as long as four, that were dug at least a mile and a half (1.6 kilometers) deep. So that no one could fire more than a few yards from any one end, the trenches were dug in a zigzag pattern. The principal trench lines were connected to one another and to the rear by communications trenches that ran almost perpendicular to them. Supply lines ran through the trenches, as did the mail, orders, food, weapons, and men. There were command posts, advance supply dumps, first aid stations, cooks, and latrines in the complex trench system. The majority of the defenders were in parallel trenches. The artillery of the enemy was hidden behind the main lines of defense. Throughout World War I, both sides dug deeper trenches to halt enemy advances. But, the Germans' efforts were particularly successful. The Germans' pillboxes were very sophisticated fortifications. There was no way for the Germans to fire upon these trenches (22 KM). Infantry attacks on the Western Front of World War I were typically preceded by massive artillery bombardments in order to break through the enemy trench system. The forewarning of the impending onslaught gave the defenders time to gather their forces for a counterattack, and the rough, shell-pocked terrain created in the "no man's land" between the two sides made further progress for the attacking infantry more difficult. Hence, it was extremely difficult to surprise and overpower a trench system.