Mortars are the oldest and
most widely used artillery,
and were a critical element of trench warfare during World War I.
Before the beginning of the Great Patriotic War, the USSR underwent something of a mortar craze. The weapon was lightweight, cheap, and easy to manufacture and maintain, so mortars often replaced other types of artillery.
In 1943, a 160mm mortar entered service. Soviet artillerymen on the front lines often prepared several firing positions, to increase their chances of striking the target. When their calculations were made with care, they could unleash a column of fire. Over the course of the war, the USSR produced 347,900 mortars.