The military history of the United States during World War II covers the nation's role as one of the major Allies in their victory over the Axis powers. The United States is generally considered to have entered the conflict with the 7 December surprise attack on Pearl Harbor by Japan and exited it with the surrender of Japan in 2 September Roosevelt in While officially neutral, the U. During the war, some 16,, Americans served in the United States Armed Forces , with , killed and , wounded.
Stimson , who mobilized the nation's industries and induction centers to supply the U. Army , commanded by General George C. The U. King , proved more autonomous. The defeat of the Nazis was the U.
Admiral King put Admiral Chester W. Nimitz , based in Hawaii, in charge of the Pacific War against Japan. The Imperial Japanese Navy had the advantage, taking the Philippines as well as British and Dutch possessions and threatening Australia. However, in June , its main carriers were sunk during the Battle of Midway , and the Americans seized the initiative. The Pacific War became one of island hopping , so as to move air bases closer and closer to Japan.
With its merchant fleet sunk by American submarines, Japan ran short of aviation gasoline and fuel oil, as the US Navy in June captured islands within bombing range of the Japanese home islands. Strategic bombing directed by General Curtis Lemay destroyed all the major Japanese cities, as the U.
With the atomic bombings of Hiroshima and Nagasaki , the Soviet invasion of Manchuria , and the imminent invasion of the home islands , Japan surrendered. The war in Europe involved aid to Britain, its allies, and the Soviet Union, with the US supplying munitions until it could ready an invasion force.
