The Big Three Meet in Tehran:
As World War II raged around the globe, the President of the United States, Franklin D. Roosevelt, began calling for a meeting of the leaders from the key Allied powers. While the Prime Minister of Great Britain, Winston Churchill, was willing to meet, the Premier of the Soviet Union, Joseph Stalin, played coy. Desperate to make a conference happen, Roosevelt conceded several points to Stalin, including choosing a location that was convenient to the Soviet leader. Agreeing to meet in Tehran, Iran on November 28, 1943, the three leaders planned to discuss D-Day, war strategy, and defeating Japan.
Wishing to present a unified front, Churchill first met Roosevelt in Cairo, Egypt on November 22. While there, the two leaders met with Chinese Generalissimo Chiang Kai-shek and discussed war plans for the Far East. While in Cairo, Churchill was unable to engage Roosevelt regarding the upcoming meeting in Tehran and the American president remained withdrawn and distant. Arriving in Tehran on November 28, Roosevelt intended to deal with Stalin personally, though his declining health prevented him from operating from a position of strength.
The first of only two wartime meetings between the three leaders, the Tehran Conference opened with Stalin brimming with confidence after several major victories on the Eastern Front. Opening the meeting, Roosevelt and Churchill sought to ensure Soviet cooperation in achieving the Allies' war policies. Stalin was willing to comply, however he demanded Allied support for his government and the partisans in Yugoslavia, as well as border adjustments in Poland. Agreeing to Stalin's demands, the meeting moved onto the planning of Operation Overlord (D-Day) and the opening of a second front in Western Europe.
Though Churchill advocated for an expanded Allied push through the Mediterranean, Roosevelt, who was not interested in protecting British imperial interests, insisted that the invasion take place in France. With the location settled, it was decided that the attack would come in May 1944. As Stalin had been advocating for a second front since 1941, he was very pleased and felt that he had accomplished his principal goal for the meeting. Moving on, Stalin agreed to enter the war against Japan once Germany was defeated.
As the conference began to wind down, Roosevelt, Churchill, and Stalin discussed the end of the war and reaffirmed their demand that only unconditional surrender would be accepted from the Axis Powers and that the defeated nations would be divided into occupation zones under American, British, and Soviet control. Other minor issues were dealt with before the conference's conclusion on December 1 including the three agreeing to respect the government of Iran and to support Turkey if it was attacked by Axis troops.
Departing Tehran, the three leaders returned to their countries to enact the newly decided war policies. As would happen at Yalta in 1945, Stalin used Roosevelt's weak health and Britain's declining power to dominate the conference and achieve all of his goals. Among the concessions he gained from Roosevelt and Churchill was a shifting of the Polish border to the Oder and Neisse rivers and the Curzon line, as well as de facto permission to oversee the establishment of governments as countries in Eastern Europe were liberated. Many of these concessions helped set the stage for the Cold War once World War II ended.