December 7th. The Japanese Imperial Navy cripples the U.S. Pacific fleet with a surprise air attack on Pearl Harbor, Hawaii.

The U.S.A., Canada, and Great Britain declare war on the Japanese Empire the next day. The U.S.A. also declares war on Nazi Germany.

The Americans had anticipated some form of attack on one of their Pacific bases, but they failed to understand how dangerous air power had become, when combined with bold, creative leadership. The Japanese attack showed the world that long distance naval air attacks had replaced battleships as the most powerful force at sea.

Here is a recreation of the Pearl Harbor attack from the 1970 film, "Tora, Tora, Tora":

"The Attack Begins" from "Tora, Tora, Tora" (1970) 6:42