trench warfare
Trench warfare was a tactic where both sides built trenches in the ground. The forward trench would be where units prepared for a charge and defended charges. Smaller trenches connected that trench to three or more rear trenches. These served as fall back positions, supply storage, and hospitals. The rear trench often had artillery in or behind it. Because of the trench structures months could go by with the front line only changing by a mile.