The significant global event that occurred on December 7, 1941, was the Japanese attack on Pearl Harbor, Hawaii. This surprise military strike targeted the United States naval base and aimed to incapacitate the U.S. Pacific Fleet. The attack resulted in substantial losses, including the destruction of numerous naval vessels, aircraft, and over 2,400 American lives. The event led to the United States formally entering World War II, declaring war on Japan the following day. Pearl Harbor is a pivotal moment in modern history, symbolizing the shift in U.S. foreign policy from isolationism to active engagement in global conflicts.