Final answer:
The Japanese attack on Pearl Harbor occurred on December 7, 1941, leading to the US entering WWII and shifting the dynamics of the war.
Step-by-step explanation:
The Japanese surprise attack on the US Pacific fleet occurred on December 7, 1941. This attack, aimed to cripple American naval power, was a significant catalyst for the United States entering World War II (WWII). Although the attack on Pearl Harbor was initially seen as a tactical victory for Japan, it had the unintended consequence of uniting the American public and bringing the US into the war.
The attack on Pearl Harbor significantly damaged the US fleet, with 8 battleships, several other vessels, and over 200 aircraft destroyed or damaged, and it resulted in the deaths of over 2,000 US servicemen and servicewomen. However, the Japanese failed to destroy the US aircraft carriers, which proved crucial in the later US victories in the Pacific.
Moreover, President Roosevelt declared December 7th as "a date which will live in infamy," and the subsequent US declaration of war against Japan led to Germany and Italy declaring war on the US, thereby deepening the United States' involvement in the global conflict.