President Franklin D. Roosevelt delivered his "Day of Infamy" speech on December 8, 1941, the day after Japan's surprise attack on Pearl Harbor. In this address to a joint session of Congress, Roosevelt described the attack as a "date which will live in infamy," emphasizing the unprovoked nature of the assault that resulted in significant loss of American lives and naval assets. The speech called for a declaration of war against Japan, marking the United States' official entry into World War II. Roosevelt’s poignant and resolute rhetoric helped galvanize public support for the war effort and illustrated the nation's determination to respond to the aggression.