Overview: December 7th 1941 is “a date that will live in infamy”proclaimed President Franklin Roosevelt. That was the day that Japan entered World War II, with its surprise attack upon theU.S. Fleet in Pearl Harbor. Japan swiftly followed this up with the defeat of a huge British army in Singapore. For a while Japan was rampant in the Pacific. But gradually, America, the sleeping giant, awoke. The war that would follow would be characterized by major innovations.