How (Almost) Everyone Failed to Prepare for Pearl Harbor

Definitely, ignoring intelligence and becoming complacent are ingredients for defeat. We missed the "memo" on Pearl Harbor and 911. Take a lesson from History.

No one failed to prepare. The Japanese were as crippled by the sanctions as we thought they'd be. The Japanese were left with no choices just as we thought they'd be. The only things that were a surprise to us were -

a. The Japanese defeating us as quickly as they did. We expected to lose men/material/land; we just didn't expect them to get so much so quickly. Though to be fair, there were several unforseen command blunders that allowed the Japanese free reign...

b. Germany declaring war on us. Although allies with Japan, note that Japan did not reciprocate. When Germany invaded Western Europe, Japan did not ally with Germany (which is odd as Japan didn't become oil dependent overnight). Japan - acting as a German ally - could have seized the Dutch East Indies a whopping two years earlier. Additionally, a German invasion of Russia would have made Japanese dreams come true quicker, had they got involved. So due to Japanese neutrality, it was a shock for Germany to jump on to a Japanese decision.