Abridged from Stuff Doesn’t Just Happen: The Gift of Failure.

I go through the seven Cascade Events that led to Pearl Harbor in detail in the book, but here they are listed:

1. Political misunderstanding and maneuvers that backfired. Both sides misunderstood the objectives of the other.
2. Military strategic planners in both countries seriously miscalculated each other. The Japanese over-estimated the United States’ Plan Orange. The United States under-estimated the Japanese potential for attack.
3. Warnings were ignored and/or not given to those who needed to get the warnings.
4. Tactical considerations worked both ways. The Japanese focused on destroying battleships while using their aircraft carriers which showed a serious blind spot in their tactics. Ultimately the war in the Pacific was a carrier war. The Americans though Pearl Harbor was too shallow for effective torpedo attack by plane.
5. New technology was not used correctly. The United States failed to properly utilize radar.
6. Timing is everything.
7. At 7:48 am on December 7^th, 1941, the Japanese Empire conducted a surprise assault on the island of Oahu, primarily focused on the American Pacific Fleet in the harbor, with a secondary objective of destroying military aircraft at outlying bases.

The final tally was:

Navy: 2,009 KIA; 710 wounded.

Army: 218 KIA; 364 wounded.

Marines: 109 KIA; 69 wounded.

Civilians: 68 killed; 35 wounded.

Aircraft:

Navy: 92 destroyed; 31 damaged.

Army Air Corps (there was no separate Air Force branch at the time): 77 destroyed; 128 damaged.

Ships:

Battleships: 2 destroyed; 6 damaged.

Cruisers: 0 destroyed; 3 damaged.

Destroyers: 0 destroyed, 3 damaged.

Auxiliaries: 1 destroyed, 4 damaged.

The United States came back from the devastation of the Pearl Harbor attack even faster than Admiral Yamamoto had feared. At the Battle of the Coral Sea, 7-8 May 1942, the Navy stopped the Japanese from advancing (although the Lexington was sunk). On at the Battle of Midway, 4-7 June 1942, the U.S. Navy delivered a devastating blow, sinking four Japanese carriers and turning the tide of the war.