Trench warfare is a form of land warfare using occupied fighting lines consisting largely of trenches, in which troops are significantly protected from enemy fire, and sheltered from artillery. Trenches were often surrounded with barbed wire, a new advancement, in order to strengthen defense. This was one of the most grueling forms of warfare in World War I, with fully exposed areas between each trench, and attacks often sustained severe casualties.

TRENCH WARFARE DURING WORLD WAR I