b) Pearl Harbor Attack

The attack on Pearl Harbor on December 7, 1941, marked the end of American isolationism in World War II. This surprise military strike by the Imperial Japanese Navy against the U.S. naval base in Hawaii led to the United States’ formal entry into the war. The attack resulted in significant loss of life and damage to the U.S. Pacific Fleet, galvanizing American public opinion and decisively shifting the U.S. stance from neutrality to active engagement in the global conflict.