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Pacific 1939-1945: Iwo Jima

Why was the battle for Iwo Jima so important to America?

Extracts from a report comparing the Allied campaigns at Iwo Jima and Okinawa, June 1945

Catalogue ref: WO 208/1021

Report on Allied campaigns at Iwo Jima and Okinawa, 1945; WO 208/1021 Report on Allied campaigns at Iwo Jima and Okinawa, 1945; WO 208/1021

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What is this source?

This source is an extract from a report looking at the experience of US troops fighting at Iwo Jima and the next big landing they took on, the island of Okinawa.


Okinawa was a much larger island than Iwo Jima with several large towns. It was also much closer to the main islands of Japan.

What’s the background to this source?

During the 1930s Japan emerged as a major world power. It had ambitions to build a great empire in Asia and the Pacific. To do this Japan would have to defeat the USA. In December 1941 Japanese forces attacked and sank the US Pacific fleet in Pearl Harbor, Hawaii. Japanese successes continued into 1942 until May of that year when US forces destroyed Japan’s aircraft carriers at the Battle of Midway. From this point the USA gradually drove Japanese forces back. By 1945, US forces reached the island of Iwo Jima, the first of Japan’s homelands. Iwo Jima was taken after a month of fighting and US forces moved on to the island of Okinawa.


The Japanese plan at Iwo Jima was to cause as many casualties as possible to the invading Americans. They fought ferociously. When the battle ended on March 16th 1945 US casualties totalled almost 28,000 (with over 8,000 dead). Japanese casualties were almost 21,000 dead out of a force of 22,000. Those not killed in fighting committed suicide. It was a similar picture at Okinawa. Here the Japanese had more than 100,000 troops and virtually all of them died fighting the invading Americans.

It’s worth knowing that...

The casualties suffered by US Marines at Iwo Jima were the highest they suffered in the war. Almost one third of all Marines killed in WW2 died at Iwo. Over a quarter of the Medals of Honour won by Marines were won at Iwo Jima. The fighting was equally bitter at Okinawa, but was spread out over a bigger island.


Military advisers estimated that if the Allies had to carry on fighting in this way then the war would last into 1946 and the Allies would suffer over 200 000 more casualties. This seems to have been a key reason why the decision was taken to use the Atomic bomb against Japan.

How will you use this source?

  1. According to this source, did the Japanese use the same tactics on Okinawa as they did at Iwo Jima?
  2. How reliable is this conclusion?
  3. What differences were there between the two campaigns?
  4. Were casualty rates and casualty numbers similar?
  5. If you were a politician or a military commander in 1945, how would you view the prospect of invading the rest of the islands that made up Japanese territory?
  6. Is there any information from the source or notes that you could use in your presentation?