The Big Three was was the name for the three leaders who met at Tehran, Yalta, and Potsdam to determine the outcome of WWII.
Also called Grand Alliance, the Big Three were composed of the three main Allied powers: Soviet Union, United Kingdom, United States, and their respective leaders, Josef Stalin, Winston Churchill, and Franklin D. Roosevelt. The Big Three were formed to fight against the Axis and reunited several times to discuss their efforts during the war. These meetings were called conferences and were held in Cairo, Tehran, Yalta, and Potsdam.