Financially, militarily, and ideologically, the United States had aligned itself with Britain, and Roosevelt expected that the nation would soon be formally at war. As Germany and Italy successfully expanded their empires, they endangered U.S. economic interests and democratic values. President Roosevelt believed that American security abroad was threatened by the German Nazis and Italian Fascists. After passage of the Lend-Lease Act, American and British military planners agreed that defeating Germany would become the top priority if the United States entered the war. In August 1941, Roosevelt and British prime minister Winston Churchill met in Newfoundland, where they signed the Atlantic Charter, a lofty statement of war aims that included principles of freedom of the seas, self-determination, free trade, and “freedom from fear and want”—ideals that laid the groundwork for the establishment of a postwar United Nations. At the same meeting, Roosevelt promised Churchill that the United States would protect British convoys in the North Atlantic as far as Iceland while the nation waited for a confrontation with Germany that would rally the American public in support of war. The president got what he wanted. After several attacks on American ships by German submarines in September and October, the president persuaded Congress to repeal the neutrality legislation of the 1930s and allow American ships to sail across the Atlantic to supply Great Britain. By December, the nation was close to open war with Germany.

The event that finally prompted the United States to enter the war, however, occurred not in the Atlantic but in the Pacific Ocean. For nearly a decade, U.S. relations with Japan had deteriorated over the issue of China’s independence and maintaining the Open Door to Chinese markets. The United States did little to challenge the Japanese invasion and occupation of Manchuria in 1931, but after Japanese armed forces moved farther into China in 1937, the United States supplied arms to China.

Relations worsened in 1940 when the Japanese government signed the Tripartite Pact with Germany and Italy, which created a mutual defense agreement among the Axis powers. That same year, Japanese troops invaded northern Indochina, and Roosevelt responded by embargoing sales of products that Japan needed for war. This embargo did not deter the Japanese; in July they occupied the remainder of Indochina to gain access to the region’s natural resources. The Roosevelt administration retaliated by freezing Japanese assets and cutting off all trade with Japan.

On the quiet Sunday morning of December 7, 1941, Japan attacked the U.S. Pacific Fleet stationed at Pearl Harbor in Honolulu, Hawaii. This surprise air and naval assault killed more than 2,400 Americans and seriously damaged ships and aircraft. The bombing raid abruptly ended isolationism and rallied the American public behind President Roosevelt, who pronounced December 7 “a date which will live in infamy.” The next day, Congress overwhelmingly voted to go to war with Japan, and on December 11 Germany and Italy declared war on the United States in response. In little more than a year after his reelection pledge to keep the country out of war, Roosevelt sent American men to fight overseas.

REVIEW & RELATE

How did American public opinion shape Roosevelt’s foreign policy in the years preceding U.S. entry into World War II?

What events in Europe and the Pacific ultimately brought the United States into World War II?