Trench warfare in World War 1 involved soldiers digging elaborate networks of trenches. Soldiers would occupy these trenches, facing the enemy across a "no man's land" often filled with barbed wire and other obstacles. Combat involved periodic offensives where soldiers would attempt to break through enemy lines, usually resulting in heavy casualties. Conditions in the trenches were grim, with constant exposure to mud, water, and disease. Artillery bombardments, machine gun fire, and occasional gas attacks added to the danger and horror of trench life.