Even as the war raged, a series of meetings between Allied leaders formulated plans for the postwar world. Churchill, Roosevelt, and Stalin met at Tehran, Iran, in 1943, and at Yalta, in the southern Soviet Union, early in 1945, to hammer out agreements. The final “Big Three” conference took place at Potsdam, near Berlin, in July 1945. It involved Stalin, Truman, and Churchill (replaced midway in the talks by Clement Attlee, who became prime minister when his Labour Party swept the British elections). At Potsdam, the Allied leaders established a military administration for Germany and agreed to place top Nazi leaders on trial for war crimes.
Relations among the three Allies were often uneasy, as each maneuvered to maximize its postwar power. Neither Britain nor the United States trusted Stalin. The delay in the Allied invasion of France until 1944, which left the Soviets to do the bulk of the fighting against Germany, angered the Russians. But since Stalin’s troops had won the war on the eastern front, it was difficult to resist his demand that eastern Europe become a Soviet sphere of influence (a region whose governments can be counted on to do a great power’s bidding).