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Pacific 1939-1945: Pearl Harbor

Why was the USA so unprepared for the attack on Pearl Harbor in 1941?

Extracts from an American report on the attack on Pearl Harbor in 1941

Catalogue ref: WO 208/2081

Extracts from an American report on the attack on Pearl Harbor in 1941; WO 208/2081 Extracts from an American report on the attack on Pearl Harbor in 1941; WO 208/2081

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What is this source?

These extracts come from an American report produced in 1945 on what happened at Pearl Harbor and who was responsible.


An American officer had produced an earlier report in 1944 but saw no evidence in 1945 to change his mind.

What’s the background to this source?

WW2 broke out in Europe in 1939. The USA was neutral in the early stages of the war although it was clear that US President Roosevelt was no friend of Nazi Germany or its ally Japan. In Japan, hard line military commanders had become increasingly powerful during the 1930s. Japan had built up an empire in Asia and these leaders wanted Japan to become Asia’s leading power. They knew that the USA would stand in their way and that war with America would happen some time. They decided to try and knock out the US fleet in the Pacific. The plan was to buy time to build up their resources in the Pacific so that Japan would be ready to take on the USA once it recovered from the attack at Pearl Harbor.


There were large numbers of Japanese settlers in Hawaii in 1941. Some were Japanese immigrants but far more were descendants of immigrants and were therefore American citizens. Even so, around 120000 Japanese Americans were placed in camps during the war.

It’s worth knowing that...

General Short was the overall commander in charge of the base at Pearl Harbor. The other senior commander was Admiral Kimmel. In the enquiry after Pearl Harbor these two men got most of the blame for the US being unprepared for the attack.


After Japan surrendered in September 1945 intelligence officers went through Japanese records and interviewed Japanese officers about key events in the war. This led to demands for re-opening the enquiry into Pearl Harbor. This did happen but it was found that no new evidence came to light that changed the verdict. General Short and Admiral Kimmel were held responsible.

How will you use this source?

  1. What was the biggest misjudgement that General Short made?
  2. Was he the only person who thought this way?
  3. Why did General Short think this way?
  4. What factors could be used to defend General Short?
  5. What points are used against him?
  6. Do you think it was fair that Short got most of the blame?
  7. Could any parts of this source be used as evidence in your report on the key question?

Use this table to help plan your report.