The United States did not just enter the war they enter ther war after the japanese bombed the American fleet in Pearl Harbor, Hawaii, on December 7, 1941. and also if you wanted to know the world war ll was (1939-1945)
Technically we had been supplying arms to England for years to fight off the axis powers, but we did not officially enter the war until immediately after december 7, 1941 which was the day of the pearl harbor bombing.
