Depth Charge, a device for sinking submarines. It consists of an explosive, usually weighing about 500 pounds (225 kg), inside a steel drum. It was widely used in both World Wars, but has now been largely replaced by more accurate weapons, such as rocket-assisted torpedoes.
The depth charge was rolled over the stern of a vessel or fired by special guns when the ship was over the suspected position of an enemy submarine. The charge could also be dropped from aircraft. A fuse would explode the charge at a preset depth. The explosion thrust pressure waves against the submarine's hull, and if close enough would crush the hull, sinking the submarine. Hundreds of depth charges were often needed for one “kill.” The weapon was developed in England in 1916.