Japanese expansion in Asia and the Pacific
Empire, resources and a war that began before Pearl Harbor
1931–1945
Japan’s imperial expansion included the conquest of Chinese territory and later Southeast Asia and the Pacific. Its goal was political and economic predominance, although Japanese propaganda spoke of freeing Asia from the West. A prolonged war in China, the need for resources and decisions to expand further connected the Asian conflict to the world war.
From Manchuria to war in China
In 1931, the Japanese Army used the Mukden incident to invade Manchuria. The proclaimed state of Manchukuo had separate institutions but was controlled by the local Japanese Army. The League of Nations’ refusal to recognise it did not reverse Japanese control.
In 1937, clashes escalated into full-scale war with China. Japanese forces captured Shanghai and Nanjing, but China’s government moved to Chongqing and continued resisting. Capturing cities did not mean Japan had achieved a decisive victory.
Resources and “co-prosperity”
Japan’s government presented its Greater East Asia Co-Prosperity Sphere as an end to Western domination. The project sought to enhance Japanese wealth and end dependence on Western supplies, rather than promise genuine independence to subjected peoples.
The United States was a major supplier of oil and other materials needed by Japan’s armed forces. As war continued in China and Japan advanced into Indochina, the US restricted trade and supported China. Japanese military leaders rejected withdrawal from China, an important condition in American negotiations.
The decision to widen the war
Japanese leaders planned to acquire Southeast Asia’s resources and establish a protective Pacific perimeter. Neutralising the American fleet was intended to limit US intervention during these conquests. The 7 December 1941 attack on Pearl Harbor formed part of wider attacks on American and British territories, rather than an isolated episode.
The roles of prime minister Hideki Tōjō and Emperor Hirohito help distinguish particular actors within the state. By spring 1942, Japan and its Thai ally had taken Singapore, Malaya and the Dutch East Indies, among other territories.
What conquest meant for inhabitants
Japanese rule over conquered territories involved violence and the use of people for wartime needs. Diplomatic reports from Nanjing document killings and sexual violence. Civilians and prisoners of war were forced to work in Japan and its occupied territories. The promise of liberation should not be confused with people’s experience under Japanese power.
From reversal to defeat
After the loss of carriers at Midway in 1942 came prolonged Allied campaigns. The Allies isolated bases, captured islands and brought bombing closer to Japan. China continued fighting. The atomic attacks and Soviet entry into the war preceded Japan’s surrender announcement on 15 August 1945; formal signature followed on 2 September. Debate about why the surrender decision was made belongs in this history, rather than a simple explanation through one blow.
Explore further
- Chiang Kai-shek and Chinese resistance
Nationalist China’s leadership in the war against Japan.
- Nanjing
The capture of the capital and violence against its inhabitants.
- Pearl Harbor
The attack that widened Japan’s conflict with the United States.