On December 7, 1941, the notable historical event was the surprise attack on Pearl Harbor by the Imperial Japanese Navy. This assault resulted in significant damage to the U.S. Pacific Fleet, with numerous ships sunk and thousands of Americans killed or wounded. The attack prompted the United States to formally enter World War II, marking a pivotal shift in American foreign policy from isolationism to active involvement in global affairs. Following the attack, President Franklin D. Roosevelt delivered his famous "Day of Infamy" speech, leading Congress to declare war on Japan the following day, which significantly altered the course of the war.