Anti-submarine mortar

Anti-submarine mortars are artillery pieces deployed on ships for the purpose of sinking submarines by a direct hit with a small explosive charge.

Anti-submarine warfare did not become an issue of great concern until World War I, when Germany used submarines in an attempt to strangle British shipping in the Atlantic Ocean and elsewhere.

The earliest way to counter a submarine was in the form of depth charges, which were large canisters filled with explosives, rolled off the back of a ship and detonated by a hydrostatic fuze.

During World War II, submarines once again posed a major threat to Allied shipping, which necessitated the development of more effective anti-submarine mortars.

Since the projectile would only explode on a hit, the long periods of sonar "blackout" from the blast and turbulence of a conventional depth charge explosion were eliminated.