Shortly afterward Roosevelt contracted polio, which left him permanently disabled but did not prevent his return to politics. Elected governor of New York in 1928, four years later he ran successfully for the presidency. In his first term as president, Roosevelt concentrated primarily on domestic affairs, launching a major reform program, the New Deal, to tackle the Great Depression and its effects. Even so, by the mid-1930s he displayed far greater determination than most Americans to check the growing influence and territorial designs of expansionist fascist dictatorships in both Europe and Asia, which he and his close advisors believed ultimately menaced American strategic, economic, and ideological interests.
Appreciable popular resistance to American intervention notwithstanding, when the general European war began in September 1939, Roosevelt unequivocally and immediately placed the United States in the broad Allied and antifascist camp. Two years of fierce debate over U.S. foreign policy ensued, during which Roosevelt moved his country ever closer to outright war with Germany while providing massive quantities of aid to Great Britain, France, and, from summer 1940, Free French forces, the Soviet Union (after June 1941), and China.
The United States entered the war as a result of the concurrent crisis in the Pacific, where Roosevelt sought to use economic policies to force the Japanese to withdraw from China and Indochina. The Japanese refused and on 7 December 1941 mounted a preemptive strike on Pearl Harbor. There is absolutely no evidence that Roosevelt knew about the attack in advance and deliberately left the Pacific Fleet exposed.
From then until 1945 the United States, Great Britain, and the Soviet Union were the senior coalition partners in the Grand Alliance against the Axis powers (Germany, Italy, and Japan). Since Roosevelt sought to build up China as a key postwar U.S. ally in Asia, at times he accorded that country similar formal status, although its military and economic weakness and semioccupation meant that it never carried the same weight as the other three. As president, Roosevelt set the parameters of American and Allied strategy. He consciously chose to place winning the war in Europe ahead of the Pacific theater and authorized the development of atomic weapons. He also presided over the forging of close permanent ties among the U.S. military establishment, science, and industry, links that later hardened into a postwar military-industrial complex.
During the war, Roosevelt met repeatedly with his Soviet and British counterparts, Soviet President Josef Stalin and British Prime Minister Winston Churchill, to reach agreement on Allied strategy and to plan for the postwar world. At Roosevelt's urging, in August 1941 Britain and the United States signed the Atlantic Charter, committing the two powers to a postwar international organization to maintain peace and to base the postwar order on principles of liberal free trade, international law, national self-determination, and human rights. Other members of the Grand Alliance later endorsed this statement, although both Britain and the Soviet Union expressed significant reservations on economic and colonial matters.
Roosevelt himself frequently expressed strong opposition to the continuation of Western imperialism after the war, sentiments that greatly irritated Churchill, who believed profoundly in the British Empire. Roosevelt was even more dedicated to ending French colonial rule, although there are indications that by early 1945 this was no longer so high a priority for him.
The British and U.S. decision to defer the cross-Channel invasion of Europe until the spring of 1944 effectively ensured that after the war Soviet military forces would control most of Eastern Europe and the Balkans. Early indications of what this would imply occurred from August to October 1944, when Soviet troops stood by while German forces suppressed an uprising in Warsaw that eliminated many potential opponents of Soviet as well as German rule. At the February 1945 Yalta Conference, the three leaders signed the Declaration on Liberated Europe supposedly promising free elections on democratic principles to all areas taken over by the Allies, but only the goodwill of the occupying powers, who could interpret them as they pleased, guaranteed these pledges. At Yalta, the Big Three also agreed to divide Germany into three temporary, separate occupation zones to be administered by their occupying military forces. Roosevelt's acquiescence in the Yalta provisions exposed him to fierce posthumous attacks from conservatives, but given the military situation on the ground, the United States and Britain had few effective means of preventing Soviet domination of the area. By the time of Roosevelt's death in April 1945, U.S.-Soviet relations were deteriorating as the brutality with which Stalin intended to impose effective Soviet domination on much of Central and Eastern Europe became increasingly apparent to often shocked Allied observers.
Roosevelt himself erroneously assumed that the postwar understanding among Britain, the Soviet Union, and the United States would endure beyond victory, envisaging a peace settlement effectively based on the delegation to each great power of a regional sphere of influence. During the war, he endorsed postwar American membership in the United Nations (UN) and newly created international economic institutions, effectively setting the United States on the path of continued involvement in international affairs, moves for which he cannily obtained bipartisan political support. He expected that the wartime Allies, as permanent members of the UN Security Council, would effectively dominate the new UN.
Under Roosevelt, the United States became the world's greatest economic and military power, a position it retained throughout the twentieth century, and moved decisively away from its limited pre-1940 internationalism. In poor health in his final year, Roosevelt did not survive to view the results of his labors. He died of a stroke at Warm Springs, Georgia, on 12 April 1945.
Roosevelt had not informed his vice president and successor, Harry S. Truman, in any detail of his future intentions in the international sphere, but Truman nonetheless promptly expressed himself as intending, with due guidance from Roosevelt's advisors, to fulfil his predecessor's postwar ambitions. Some historians, notably Daniel Yergin, have suggested that Truman was far more uncompromising in dealing with the Soviet Union than Roosevelt would have been. However, given the weakness of the ties binding the Grand Alliance once Japan had been defeated, it may well be that Roosevelt too would have faced equally great difficulties in maintaining continued harmonious relations with Stalin.
Dallek, Robert. Franklin D. Roosevelt and American Foreign Policy, 1932–1945. New York: Oxford University Press, 1995.; Gormly, James L. The Collapse of the Grand Alliance, 1945–1948. Baton Rouge: Louisiana State University Press, 1987.; Hoopes, Townsend, and Douglas Brinkley. FDR and the Creation of the U.N. New Haven, CT: Yale University Press, 1997.; Kimball, Warren F. The Juggler: Franklin Roosevelt As Wartime Statesman. Princeton, NJ: Princeton University Press, 1991.; Perlmutter, Amos. FDR & Stalin: A Not So Grand Alliance, 1943–1945. Columbia: University of Missouri Press, 1993.; Sainsbury, Keith. Churchill and Roosevelt at War: The War They Fought and the Peace They Hoped to Make. New York: New York University Press, 1994.; Yergin, Daniel H. Shattered Peace: The Origins of the Cold War. New York: Penguin, 1990.