Seventy-two years ago, a surprise attack came.
It can be argued that the attack should not have surprised naval strategists, or military leaders of that day. However, it did.
There is even evidence that the Japanese diplomats in Washington, DC did not know that their nation was shifting from negotiations into armed conflict.
Pearl Harbor is at the edge of living memory now. (Last
year at this time, I had five relative alive who could remember that
day. Now, only three are alive...) Soon, it will pass beyond living
Even so, the lesson that could be learned has probably not been learned.
Jim Miller has said a little more than I have, and probably more cogently.
His main point is cultural difference. That, blended with an ongoing simmering of preparation-for-possible-war and lack of clarity on the target chosen for military attack, kept American leaders from understanding that an attack might come in Hawaii. Worse, technological advances (some less than a few months old) gave the Japanese naval forces an edge.
The war that shaped a generation, and turned America into a dominant power on Earth, had started years earlier. But the United States was brought into that war by surprise attack.
UPDATE: like every day in history, there are many important details...and there are also interesting trivia.