One day after Japan's surprise assault on the U.S. Pacific Fleet at Pearl Harbor, Roosevelt addressed a joint session of Congress, calling December 7 'a date which will live in infamy.' Within an hour, both houses of Congress voted overwhelmingly for war, with only one dissenting vote from Representative Jeannette Rankin. The declaration formally brought the United States into World War II.
Roosevelt's seven-minute speech, delivered in his distinctive patrician cadence, was deliberately spare compared to his usual eloquence — he wanted urgency, not oratory. He revised the opening line himself from 'world history' to 'infamy,' a word choice that became instantly iconic.
The Senate voted 82-0 and the House 388-1 in favor of war, with Montana's Jeannette Rankin, a committed pacifist who had also voted against entering World War I, casting the lone dissent. She reportedly said, 'As a woman, I can't go to war, and I refuse to send anyone else.'
Roosevelt signed the declaration that afternoon. Three days later, Germany and Italy declared war on the United States in solidarity with Japan, transforming what had been a European and Pacific conflict into a fully global war. American industry, dormant through the Depression years, began its rapid mobilization into what would become the 'arsenal of democracy.'
Key people: Franklin D. Roosevelt, Jeannette Rankin