Mousetrap (weapon)
Mousetrap was an anti-submarine rocket launcher used mainly during World War II by the United States Navy and Coast Guard. Its development began in 1941 as a replacement for Hedgehog anti-submarine mortar. Hedgehogs were spigot-launched, which placed considerable strain on the launching vessel's deck, whereas Mousetrap was rocket-propelled. As a result, Mousetrap's four or eight rails for rockets saved weight and were easier to install.
The rockets weighed each, with a Torpex warhead and contact pistol, exactly like Hedgehog.
By the end of the war, over 100 Mark 22 Mousetraps were mounted in US Navy ships, including three each on 12 destroyers, and submarine chasers.