A short-barrelled cannon with plunging fire. Mortars were used mainly in fortress sieges. They were loaded with bombs or incendiary missiles and used to shell an enemy from special trenches. Before firing, the bomb fuse was ignited so that the bomb exploded the moment it reached the target. A mortar's range of fire was about 1,800-2,500 m (6,000-8,500 ft) on average. It took about 5-7 minutes to load and aim. Shooting accuracy was not very good, but the powerful explosion could cause great damage. Moreover, a mortar's plunging fire allowed it to reach targets behind walls or other obstacles.