By 1940, the Nazis held almost all of Western Europe. France surrendered to the Germans in June of that year. The Nazis seemed unstoppable.
All that stood between the Germans and Britain was the narrow English Channel.
Hitler’s success gave Japanese forces the courage to move from China into Southeast Asia. The U.S. protested. But it took no military action.
Most people in the U.S. favored the Allied cause. But they didn’t want to go to war. They saw it as a problem between European nations. And they felt protected by the oceans that separate the U.S. from Europe and Asia. President Roosevelt gave economic aid to the Allies. But he couldn’t do much more. Britain was now the free world’s leader against the Axis threat.