A possible attack on the Italian naval base at Taranto had been planned and prepared before the war. The operation called for the Swordfish aircraft to make a long distance approach with auxiliary fuel tanks.
The torpedo aircraft then had to launch their torpedoes from a steady height of 150 feet while travelling at 90 knots in order to cope with the relatively shallow water. This should have made them sitting ducks for the Anti-Aircraft guns of the Battleships and Cruisers that they were attacking, and heavy casualties were anticipated. In fact only two aircraft were shot down, the crew from one of them surviving as prisoners. Three battleships were hit by torpedoes, one was sunk and the two others seriously damaged.
The other aircraft, carrying conventional bombs and flares to illuminate the target area, caused confusion as they attacked other targets. More ships were hit as well as dockyard installations.
The attack established beyond doubt the potential of aerial launched torpedoes, even in relatively shallow harbour waters. It was closely studied by other navies around the world, not least in Japan. More immediately it shifted the balance of naval power in the Mediterranean. Not only was a significant part of the Italian fleet put out of action, many of the remaining ships were swiftly moved to ports further north, out of harms way but further from their main area of operations.