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3. The Big Three

Article The Big Three

In World War II, the three great Allied powers—Great Britain, the United States, and the Soviet Union—formed a Grand Alliance that was the key to victory. But the alliance partners did not share common political aims, and did not always agree on how the war should be fought.

Top Image: Soviet premier Joseph Stalin, US president Franklin Delano Roosevelt, and british Prime Minister Winston Churchill (left to right) at the Teheran Conference, 1943. (Library of Congress, LC-USZ62-32833.)

British Prime Minister Winston Churchill once said, “The only thing worse than having allies is not having them.” In World War II, the three great Allied powers—Great Britain, the United States, and the Soviet Union—formed a Grand Alliance that was the key to victory. But the alliance partners did not share common political aims, and did not always agree on how the war should be fought.

Churchill and US President Franklin Delano Roosevelt had been working together for some time when the United States entered the war in 1941. Roosevelt believed a British victory over the Axis was in America’s best interests, while Churchill believed such a victory was not possible without American assistance. In 1940, the two leaders worked to find ways for America to help Britain hold on without violating its neutrality. The following year they met off the coast of Newfoundland to begin planning, in sweeping terms, the postwar world. Soviet Premier Joseph Stalin was a late addition to the Big Three. On New Year’s Day 1942, representatives of all three nations signed the United Nations Declaration, pledging to join hands to defeat the Axis powers.

The Big Three faced considerable challenges in coordinating their efforts. Thousands of miles separated their capitals, which meant important decisions often had to be made by telephone or telegraph. Although their representatives met frequently during the war, Roosevelt, Stalin, and Churchill only met twice in person.

Stalin was deeply suspicious, to the point of paranoia, of both Roosevelt and Churchill.

Politics and history also made the relationship difficult. Stalin was deeply suspicious, to the point of paranoia, of both Roosevelt and Churchill. He knew his capitalist allies would likely oppose any attempt to expand Soviet influence in eastern Europe when the war ended. Stalin also complained incessantly about the Allied failure to mount a second front in western Europe before June 1944. This front, he said, would reduce pressure on the Soviet Union by forcing Hitler to transfer forces from Russia to meet the Anglo-American invasion.

Planning for the postwar era further strained relations between the Allied leaders. By the time the Big Three gathered for the last time at Yalta in February 1945, the Allies were closing in on Germany from both the east and west. Several major questions had to be settled, chief among them the fate of Poland, which was then occupied by Soviet troops that were advancing on Berlin. Stalin demanded that part of Poland be transferred to the Soviet Union and that a Soviet-friendly communist government in the city of Lublin control the remainder of the country. He also insisted that each of the Soviet Union’s satellite republics in eastern Europe receive separate votes in the newly created United Nations, even though these countries were controlled from Moscow. This alarmed Roosevelt and Churchill, but they were powerless to force Stalin to guarantee a democratic and independent Poland. Stalin’s armies already occupied most of the region, and the Western allies could not force them out without fighting the Soviet Union. Furthermore, Roosevelt hoped to have Stalin’s help in finishing off Japan.

The Yalta Conference ended in a compromise. Roosevelt and Churchill agreed to Stalin’s demands regarding Poland and the United Nations. Stalin, in return, agreed to hold elections in Poland so its people could choose their own government. He also agreed to declare war against Japan shortly after the German surrender.

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The end of the war marked the end of the Grand Alliance. Roosevelt died in April 1945 and was succeeded by his vice president, Harry S. Truman, a committed anticommunist. Churchill met briefly with Stalin at the Potsdam Conference, but was replaced halfway through it by a newly elected prime minister, Clement Attlee. Ongoing disputes between the Soviets and the democratic allies about how to organize the postwar world eventually killed the alliance. Stalin continued to expand Soviet influence in eastern Europe, while America and Britain were determined to stop him without provoking another war. This tense standoff between the former allies, which became known as the Cold War, would last for decades.

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The National WWII Museum. "The Big Three" https://www.nationalww2museum.org/war/articles/big-three. Published January 21, 2026. Accessed January 21, 2026.

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The National WWII Museum. "The Big Three" Published January 21, 2026. Accessed January 21, 2026. https://www.nationalww2museum.org/war/articles/big-three.

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