depth charge

depth charge, explosive device used against submarines and other underwater targets, either rolled into the water from rails on the stern of a ship or propelled from depth charge throwers. The charge is detonated by water pressure at a predetermined depth. It does not have to come into actual contact with the target to destroy it, since the concussion can accomplish this if the charge explodes near enough. First used by the British navy in World War I, it contributed significantly to the defeat of the German U-boat campaign.

or depth bomb

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.

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See Depth charge