Shallow-water torpedoes and the Swordfish

The Royal Navy worked to make air-dropped torpedoes enter shallow water without diving too deeply, a requirement tied directly to attacking fleets in port. Engineers refined the entry so the weapon would belly-flop and settle onto its run before reaching the harbour bottom. Extensive worldwide testing produced operational knowledge that also reduced the reliability failures experienced by several other navies at the start of the Second World War. The Swordfish complemented the weapon because it could fly low, slowly, and steadily during the demanding release. Its controllability also suited the night strikes that British carrier doctrine increasingly expected.