Hitler's violation of the Munich Pact of 1938 opened the eyes of French and British leaders, and the outbreak of World War II in September 1939, following Germany's invasion of Poland, forced Americans to reconsider. Still, while they supported the Roosevelt administration's decision to permit the Allies to buy military supplies in the United States, few seriously considered an alliance and intervention. Memories of World War I were too strong. Despite later claims that public opinion had limited his freedom of action, Roosevelt apparently agreed with the majority of Americans. He understood that Britain and France were fighting America's war but saw no need for the United States to be anything except what he later labeled "the arsenal of democracy." The collapse of French resistance in June 1940 made the president willing to lend money, equipment, and technical aid to Britain (which culminated in the Lend-Lease Act of March 1941), but he remained convinced, even until early 1941, that a military alliance, and the shedding of American blood, might be avoided.
Hitler's invasion of the Soviet Union made Roosevelt less optimistic, for it raised the specter of a level of German strength that would necessitate U.S. armed intervention, and by the fall of 1941 he had concluded that American intervention was necessary. But it took the Japanese attack on Pearl Harbor to bring the United States into the war. Only then did Americans begin to understand the degree to which an Anglo-American alliance—based upon firm entente—already existed. During 1941 the United States and Great Britain developed a remarkably close relationship at the level of military and logistical planning, based on the probability of an alliance.
Even with such close cooperation, the Anglo-American entente, like almost all other ententes and alliances, was not an equal partnership. The British found themselves repeatedly in the position of the pleader, while the United States, with its vast economic strength, soon began to act like a senior partner. Only during the early stages of the war, when the overriding concern was the prevention of a defeat at the hands of Germany and Japan, did the two nations meet on equal ground. After it had become clear that victory was certain—roughly about the time of the Tehran Conference in December 1943—the United States more and more frequently forced the British to accept American decisions, particularly with regard to matters affecting the postwar situation.
Problems with what Winston Churchill called the Grand Alliance fell into three categories: military strategy, politics, and economics. Disputes over military strategy found the Americans stubborn and rarely willing to compromise. Exhibiting a strong distaste for consistent British attempts to make war serve politics, particularly the preservation of the empire, American military leaders refused to consider any alternatives that did not combine the quickest and least costly path to victory. Except for the invasion of North Africa, Roosevelt refused to overrule his military chiefs of staff, and that one exception came more from his desire to get American troops into action than because he accepted Churchill's grand strategy. The Normandy invasion, the daylight bombing of Germany, and the invasion of southern France are only the most striking examples of America's insistence upon implementing its own military strategy.
As ever, economics and politics interacted. Economic diplomacy between Britain and the United States, at least as it related to the critically important questions of the structure of the postwar world, found the Americans rigid in their views. That rigidity was modified by the American desire for a postwar political alliance with Britain. Thus, the United States could and did demand that Britain eliminate the imperial preference system, which gave special trading benefits to members of the British Empire. The British realized that the system itself had outlived its usefulness; but when the Americans pressed Britain to give up its colonies, the Churchill government dug in its heels. Faced with that response, Roosevelt backed off, partly in order to preserve the wartime alliance, but more and more in the later stages of the war because of his commitment to an Anglo-American political alliance in the postwar world.
A good example of this interplay between economic and political desires is in the case of atomic energy. Early in the war, the United States and Great Britain had agreed to work together to develop an atomic bomb. Initially, that cooperation was stimulated by fears that the Germans would develop the bomb first. But midway through the war, once the British had no more to offer, Roosevelt, at the instigation of his advisers, cut off the flow of information on atomic energy to England. They argued that Britain wanted to be privy to the secret in order to use atomic energy for commercial purposes after the war and that sharing nuclear knowledge would tie the United States to England politically—a reference to Britain's colonial problems. When Churchill protested vigorously, Roosevelt changed his mind. Not only had the president begun to worry about Britain's economic problems following the war, but he had come to assume Anglo-American alliance—and their atomic monopoly after the war.
The Anglo-American entente was the deepest commitment made by the United States during World War II, but the coalition with the Union of Soviet Socialist Republics proved the most important—and the most difficult. Even during the early 1930s, Franklin Roosevelt's attitude toward the Soviet Union had been one of practicality and persuasion, and once Hitler had invaded the Soviet Union, the president's nonideological stance made it easy to welcome the Russians as a military partner. Although Roosevelt has frequently been criticized as a political "fixer" rather than a man with an organized grand strategy, he clearly recognized the cardinal fact of the Russo-American coalition: if it defeated Germany and Japan (a certainty after the battles of Kursk, Stalingrad, El Alamein, and Midway—all by mid-1943), the Soviet Union would pose the major barrier to Anglo-American predominance in the postwar world. That left Roosevelt three simple but critical alternatives. First, he could include the Russians in the postwar power structure, hoping they would moderate their political and economic demands. Second, he could begin to confront Soviet power during the war by shaping military planning to meet postwar political needs. Third, he could firmly confront Soviet power late in the war, but only after military victory over Germany and Japan had been assured.
Despite advice from many, including Churchill, Roosevelt based his policy on the principle that the United States was not fighting one war in order to lay the groundwork for the next. Roosevelt refused to follow the path of confrontation; but cooperation, during and after the war, did not mean simple compliance with every Russian political demand nor did it mean that Roosevelt expected postwar Soviet-American relations to be without serious tensions. He merely emphasized the positive approach in the hope that it would engender a similar response. Nor was the dire warning given Roosevelt about Soviet intentions timely, for most came late in the war and well after most of the basic military strategies had been carried out.
Roosevelt's strategy failed to take into account the magnitude of the Soviet Union's distrust of the capitalist nations as well as his own advisers' intense fear of communism. He was by inclination a believer in personal diplomacy, and the general lack of enthusiasm within the U.S. State Department for a cooperative policy toward the Soviet Union forced Roosevelt to rely even more heavily on his own power and ability to shape events. More significantly, his conciliatory policies were not faithfully reflected by the American bureaucracy. Major changes in foreign policy can occur only when they generate the kind of national support that ensures that subordinates in the executive branch are actually thinking like the leadership. American policy toward the Soviet Union prior to World War II and the anticommunism of the Cold War show that Franklin Roosevelt's cooperative approach—a policy that foreshadowed the idea of "peaceful coexistence"—deviated from the norm of American foreign policy.
How the Soviet leaders, given their own ideological commitments and revolutionary experiences, would have responded to a totally candid and open Anglo-American policy during the war is uncertain. What is clear is that whenever Roosevelt hedged his bets—on the opening of a Second Front, on the Russian role in the occupation of Italy, on aid to left-wing partisan groups in Europe—Soviet leaders invariably accused the Anglo-Americans of playing political games. Although American policy toward Great Britain was frequently characterized by the same level of distrust as with the Russians, for example on the question of the imperial preference system, Soviet-American relations did not possess that community of interests that made it possible to transcend the differences. That, in essence, sums up the difference between an entente and a coalition.
The lesser partners in the Grand Alliance of World War II varied from such potential giants as China, to the small Central American states, to latecomers such as the newly constituted Provisional Government of the French Republic, which signed the Declaration of the United Nations in 1945. Intentionally vague, the declaration called only for mutual aid against the Axis nations and promised that no signatory would agree to a separate peace. Convinced that postwar questions were best left to personal diplomacy, Roosevelt refused to consider anything more substantial. American diplomacy during the war centered on the military defeat of the Axis, and relations with the less-important members of the United Nations were largely reserved to integrating their economic resources into the overall war production effort. Individual bureaucrats occasionally initiated and implemented policies that concerned America's postwar economic and political interests, particularly in Latin America, but such actions reflected traditional American attitudes, not any overall plan approved by the president.
Although Roosevelt's conception of a global balance of power—the Soviet Union, the Anglo-American alliance, an Anglo-French association in western Europe, and eventually China—seems reflected in the Cold War power structure that soon developed, the president's vague ideas possessed a crucial difference: they emphasized cooperation, not distrust.
By the end of World War II the United States seemed on the verge of a radical departure from past policies. With Harry S. Truman replacing Roosevelt in the White House, alliance diplomacy aimed increasingly at containing and defeating what appeared to be the new enemy, the Soviet Union. The nature of that Cold War determined part of the structure of America's alliance system, but other aspects of alliance diplomacy stemmed from traditional American attitudes.