World War II: American submarine USS Sealion sinks the Japanese battleship Kongō and Japanese destroyer Urakaze in the Formosa Strait.

World War II or the Second World War was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes.

USS Sealion (SS/SSP/ASSP/APSS/LPSS-315), a Balao-class submarine, was the second ship of the United States Navy to be named for the sea lion, any of several large, eared seals native to the Pacific. She is sometimes referred to as Sealion II, because her first skipper, Lieutenant Commander Eli Thomas Reich, was a veteran of the first Sealion (SS-195), serving on her when she was lost at the beginning of World War II. Sealion was the only US and Allied submarine that sank an enemy battleship during the Second World War.

Kongō was a warship of the Imperial Japanese Navy during World War I and World War II. She was the first battlecruiser of the Kongō class, among the most heavily armed ships in any navy when built. Her designer was the British naval engineer George Thurston, and she was laid down in 1911 at Barrow-in-Furness in Britain by Vickers Shipbuilding Company. Kongō was the last Japanese capital ship constructed outside Japan. She was formally commissioned in 1913, and patrolled off the Chinese coast during World War I.