The Japanese bombed U.S. naval bases in a surprise attack on Pearl Harbor, Hawaii, on December 7, 1941. The next day, President Franklin D. Roosevelt, as commander in chief of the military, obtained an official declaration of war from Congress. Japan’s partners in the Axis, Italy and Germany, then declared war on the United States. The Allies fought against the German Nazis, the Italian Fascists, and Japan’s military empire. This was truly a world war, with battles fought in Europe, Africa, Asia, and the Pacific Ocean.