Weapon used by ships or aircraft to attack submerged submarines. Developed by the British in World War I for use against German submarines, it consisted of a canister filled with explosives and dropped off the stern of a ship near a submerged submarine. It rarely exploded close enough to sink the submarine, but its shock waves loosened the submarine's joints and damaged its instruments, forcing it to the surface, where naval gunfire could finish it off. Modern depth charges can be fired as far as 2,000 yards (1,800 m) from a ship's deck or launched from aircraft. Atomic depth charges have a nuclear warhead and a vastly increased killing radius.