Short answers, pulled from the story.
British aircraft launched from the carrier Illustrious attacked Italian battleships in Taranto harbor. The strike damaged three capital ships including Conte di Cavour, Duilio, and Littorio while sinking one permanently out of service.
A drum attached beneath each torpedo prevented weapons from diving too deep into waters only twelve meters deep. This belly-flop technique allowed effective strikes despite the harbor depth being insufficient for standard torpedoes.
Admiral Andrew Cunningham led the British Mediterranean Fleet against the Italian Regia Marina. He authorized Operation Judgment which utilized Fairey Swordfish biplane torpedo bombers for night attacks.
Italian shipping increased significantly between October 1940 and January 1941 averaging 49,435 tons per month after the raid. Admiral Inigo Campioni sortied with two battleships and six cruisers just five days later to disrupt Axis supply lines.
Imperial Japanese Navy staff studied the raid including Lieutenant Commander Takeshi Naito who visited Taranto in May 1941. They applied shallow-water solutions developed since early 1939 to their December 1941 attack on Pearl Harbor.