"A day that will live forever in infamy," said Franklin Roosevelt. The phrase has been used many times since, sometimes for the most trivial and inconsequential things imaginable. (A character got written out of your favorite soap opera? Give me a festering BREAK!)
In the wake of Pearl Harbor, the United States entered the Second World War, changing the course of the war and of world history forever. America built a new, better, stronger fleet, and came to dominate first the Pacific, then much of the world. Interestingly, Admiral Isoroku Yamamoto warned the Japanese government that he thought it was a very bad idea. They went ahead with the plan anyway.
Thus is history shaped.