Leaning heavily on the arm of his son James, a Marine captain, FDR walked haltingly into the House of Representatives at noon to request a declaration of war from the House and address the nation via radio. "Yesterday," the president proclaimed, "December 7, 1941—a date which will live in infamy—the United States of America was suddenly and deliberately attacked by naval and air forces of the Empire of Japan. No matter how long it may take us to overcome this premeditated invasion, the American people in their righteous might will win through to absolute victory."
Roosevelt's 10-minute speech, ending with an oath-"So help us God"—was greeted in the House by thunderous applause and stamping of feet. Within one hour, the president had his declaration of war, with only one dissenting vote, from a pacifist in the House. FDR signed the declaration at 4:10 p.m., wearing a black armband to symbolize mourning for those lost at Pearl Harbor.
On both coasts, civilian defense groups were mobilized. In New York, Mayor Fiorello LaGuardia ordered the rounding up of Japanese nationals, who were transported to Ellis Island and held in custody indefinitely. In California, antiaircraft batteries were set up on Long Beach and the Hollywood Hills. Reports on supposed spy activity on the part of Japanese Americans began pouring into Washington, even as Japanese Americans paid for space in newspapers to declare unreservedly their loyalty to the United States. The groundwork was being laid for the tragic internment of Japanese Americans, thought a necessary caution at the time but regretted years later as a hysterical and bigoted response.