 It was the first of the World War II conferences of the "Big Three" Allied leaders (the Soviet Union, the United States, and the United Kingdom).It closely followed the Cairo Conference which had taken place on 22–26 November 1943, and preceded the 1945 Yalta and Potsdam conferences.Although the three leaders arrived with differing objectives, the main outcome of the Tehran Conference was the Western Allies' commitment to open a second front against Nazi Germany.