. . "How long was World War II and who won"@en . "World War II lasted 6 years and 1 day from September 1 1939 to September 2 1945. The Allies won the war. The Allies mainly were the United Kingdom, United States, and the Soviet Union."@en . . "World War II lasted 6 years and 1 day from September 1 1939 to September 2 1945. The Allies won the war. The Allies mainly were the United Kingdom, United States, and the Soviet Union."@en .