Upon entering the war, President Roosevelt believed that the greatest threat to the long-term survival of democracy and freedom would be a German victory. Hence, he entered into an alliance with British prime minister Winston Churchill and Soviet premier Joseph Stalin to defeat the common enemy while also seeking to lay the foundation for a peaceful postwar world in which the United States would play a major and permanent role. Appeasement and nonintervention had been proven to be shortsighted and tragic policies that failed to provide security and peace either for the United States or for the world.
With the aid of the British, the United States invaded North Africa and from there invaded Europe by way of Italy. However, the cross-channel invasion of Europe through France that Stalin had long called for did not come until 1944, by which time the Soviets had turned the tide of battle in eastern Europe. The liberation of Hitler’s concentration camps forced Allied nations to confront the grisly horrors that had been taking place as the war unfolded. The Big Three met for one last time in February 1945, at Yalta, where Churchill and Roosevelt agreed to several conditions that strengthened Stalin’s position. They planned to finalize their plans at a later conference, but Roosevelt died two months later.