World War II officially ended with the signed Japanese surrender on Sept. 2, 1945. Germany had already surrendered on May 8, 1945, ending the war in Europe.
The Japanese agreed to the surrender on Aug. 14, 1945, under the Potsdam Declaration. This occurred shortly after the United States dropped two nuclear bombs in Japan. Japan was the last Axis Power to give up arms.
Japan, Italy and Germany composed the Axis Powers. The main Allied Powers included Great Britain, the United States, China and the Soviet Union. World War II began on Sept. 1, 1939, with the German invasion of Poland.