Answer:
The war started with Nazi Germany's assault on Poland in September 1939, the United States did not enter the war until after the Japanese shelled the American armada in Pearl Harbor, Hawaii, on December 7, 1941.
Among the war's significant defining moments for the United States were the Battle of Midway (1942), the intrusion of Italy (1943), the Allied attack of France (1944), the clash of Leyte Gulf (1944) and the dropping of the nuclear bombs on Japan (1945). The war finished with the Axis forces' genuine surrender in 1945.