Tehran Conference , a World War II meeting of the “Big Three” Allied leaders -- President Franklin D. Roosevelt of the United States, Prime Minister Winston Churchill of Great Britain, and Premier Joseph Stalin of the Soviet Union. It was held at Tehran, Iran, from November 28 to December 1, 1943, just after the first Cairo Conference. It was the first meeting to bring all three of the leaders together.

At the Tehran Conference it was decided that the next major campaign for the British and Americans would be the invasion of western France. It was also decided to invade southern France at a later date, and Stalin agreed to enter the war against Japan once Germany was defeated. Also discussed were plans for the postwar world, including some form of peacekeeping organization.

Tehran Conference, 1943.Tehran Conference, 1943. Shown are the "Big Three" Allied leaders (from left): Premier Joseph Stalin of the Soviet Union, Pesdient Franklin D. Roosevelt of the United States, and Prime Minister Winston Churchill of Great Britain.