Winston Churchill knew that it was the turning point of the war. FDR had invented Lend-Lease to help Great Britain survive and to aid the U.S.S.R. Yet even Roosevelt could not lead a people that wanted to stay out of the war until Pearl Harbor.
The Japanese were supposed to meet with Secretary of State Cordell Hull on December 7th and deliver their Government's ultimatum, but delays in transcribing meant that they met with Hull after the attack. The image enraged America: the ambassadors from Japan supposedly meeting to talk peace while the Japanese military attacked Pearl Harbor on a quiet Sunday morning.
Hitler did FDR a favor. He declared war on the U.S. soon after FDR's declaration of war on Japan. Americans would have resisted a Europe First strategy without that German declaration.
The rallying cry throughout the war would be, "Remember Pearl Harbor!" A pity more people don't remember the anniversary.
American Movie Classics are showing World War II movies all day long and the 1970 film, Tora! Tora! Tora! about the attack on Pearl Harbor at 8:00 EST tonight.
Finally, here's a video of JFK visiting the Arizona Memorial in 1963. The Memorial was completed in 1962 and he was the first U.S. President to visit it. All Presidents have followed his lead.