Aerial view of the USS Arizona Memorial
It's Pearl Harbor Day. I didn't see another thread about it, so let me offer this one. December 7, 1941 was a pivotal event in American history. Before then, Americans were content with isolationism. No one accused her of being the World's Policeman. The US was not a great military power, ranking behind Portugal and Romania.
The Japanese sneak attack changed all that. America had been trying to peacefully influence the Empire of Japan to quit her war in China. Sanctions were our answer to military aggression. Japan believed a stiff, punishing attack would convince America to back off embargoes of oil and iron, which it badly needed to continue military occupation of China. 3 years, 9 months, and two atomic bombs later, Japan surrendered unconditionally and was occupied by the US.
After Pearl Harbor, the US became a great power. She was determined never again to invite military attack by having a second rate military. With devestation among other industrialized powers, the US became a "superpower" militarily and economically. Unlike what happened after WWI, the US did not beat her swords into plowshares. She continued military developments in aircraft, rocketry, and nuclear weaponry. Powerful new tanks and artillery were developed. Never again would American soldiers have to face enemies with obsolete equipment, nor would they have to train with broomsticks for machine guns.
More than 6 decades later, the US remembers December 7, 1941.