In five minutes
Japanese imperialism is the story of a country that was pressured by imperial powers and then became one itself. In the 1850s Japan was forced to sign unequal treaties with the United States and European states. Within about forty years it had rebuilt its government, army and economy, and in 1895 it took its first major colony, Taiwan. By 1945 its empire covered Korea, Taiwan, southern Sakhalin, parts of China and much of Southeast Asia and the Pacific, before collapsing in defeat.
It is one case in the larger pattern described in Imperialism: What It Was, Why It Happened, What It Left Behind. What makes Japan unusual is that it was the only non-Western state to build a major overseas empire in the age of high imperialism, and that its rule left memories that still shape relations in East Asia.
Why Japan became an imperial power
Fear of being next. In 1853 Commodore Matthew Perry's American ships arrived in Edo Bay, and the treaties that followed, including the 1858 commercial treaties, gave foreigners extraterritoriality and limited Japan's control over its own tariffs. Japanese leaders also watched Britain press China after the Opium War. They concluded that a weak state would be carved up.
A strong state. After the Meiji Restoration of 1868, the government pursued fukoku kyōhei, "rich country, strong army". It introduced conscription in 1873, built railways and factories, set up a constitution in 1889, and created a modern navy. These steps made expansion possible.
Security and resources. In 1890 Prime Minister Yamagata Aritomo described a "line of sovereignty", Japan's own borders, and a "line of interest", the neighbouring areas whose fate affected Japan's safety. Korea, so close to Japan, became the main example. Later, a lack of oil, iron and other raw materials added a second argument for expansion.
Prestige. In the late nineteenth century, owning colonies was widely treated as the mark of a great power. Japanese leaders wanted equal treatment from the West, and that included playing by the same imperial rules.
What happened
1870s–1890s: borders and Korea
Japan first fixed its own edges. Hokkaido was developed under a colonisation office from 1869. In 1875 a treaty with Russia gave Japan the Kuril Islands in exchange for Russia holding Sakhalin, and in 1879 the Ryukyu Kingdom was turned into Okinawa Prefecture. In 1876, after a naval incident at Ganghwa Island, Japan forced Korea to sign an unequal treaty modelled on the ones Japan itself had accepted. Competition for influence over Korea then pushed Japan toward conflict with Qing China.
1894–1905: two wars
In the First Sino-Japanese War (1894–95) Japan's modern army and navy defeated China. The Treaty of Shimonoseki in April 1895 gave Japan Taiwan, the Penghu Islands and a large indemnity. It also named the Liaodong Peninsula, but Russia, Germany and France pressed Japan to give it back. Japan accepted, and the humiliation encouraged it to build up for a showdown with Russia.
In the Russo-Japanese War (1904–05), Japan won on land at Mukden and at sea at Tsushima. The Treaty of Portsmouth, mediated by the United States in September 1905, gave Japan Russia's lease on the Liaodong tip, the southern branch of the Manchurian railway, southern Sakhalin, and recognition of Japan's leading position in Korea. The Anglo-Japanese Alliance of 1902 had already marked Japan's arrival as a recognised power. The victory over a European empire also drew attention across Asia.
1905–1930: Korea, China and the First World War
Korea became a Japanese protectorate in 1905, and Japan formally annexed it in 1910. In the First World War Japan joined the Allies, took the German base at Qingdao and German-held islands in the Pacific, and in 1915 presented China with the Twenty-One Demands. At the Paris Peace Conference it proposed a racial equality clause, which was not adopted, while it kept its Pacific mandates. In Korea, the huge March First Movement of 1919 was suppressed, but it pushed Japan toward a softer policy known as "cultural rule".
1931–1945: Manchukuo to the Pacific War
In September 1931 officers of Japan's Kwantung Army staged an explosion near Mukden and used it as a pretext to occupy Manchuria. In 1932 they set up the puppet state of Manchukuo. When the League of Nations criticised Japan, it left the League in 1933. Full-scale war with China began in July 1937, and in December the capture of Nanjing was followed by the killing of large numbers of civilians and prisoners. In 1940 Japan announced the "Greater East Asia Co-Prosperity Sphere", a slogan of Asian unity that in practice meant Japanese control. In December 1941 it attacked Pearl Harbor and British, Dutch and American territories in Southeast Asia. It surrendered in August 1945.
How Japan ruled its empire
Japan's colonies were run by governors-general who answered to Tokyo, and military and police played a strong role. In Taiwan, Japan put down resistance after 1895, then built railways, ports, a land survey and a sugar industry, and later pushed Japanese-language schooling. In Korea, the early years from 1910 were marked by military police rule and a land survey that moved ownership away from many farmers. After 1919 the rules eased, but in the late 1930s policy tightened again. Koreans and Taiwanese were pressed to adopt Japanese names and customs, and during the war many were sent into forced labour or military service.
In occupied China and Southeast Asia, Japan used local governments, requisitioned food and materials, and used forced labour. Historians have documented the military's system of "comfort stations", in which many women from Korea, China and elsewhere were coerced into sexual servitude. Some local people at first welcomed the end of European colonial rule, but the occupation was harsh and most hopes of liberation faded.
What it left behind
The empire ended in 1945. Japan lost all its colonies and occupied territories, and Allied forces occupied Japan until 1952. The Tokyo Trial judged leading officials for war crimes. Taiwan returned to Chinese administration, Korea was divided at the 38th parallel, and Manchuria returned to China.
The legacy is still debated. Disputes continue over history textbooks, memorials, compensation for forced labourers and the comfort women issue, and they affect Japan's relations with South Korea and China. In Southeast Asia, Japan's early victories weakened European colonial rule and helped independence movements, even though Japan itself was an oppressive occupier. Japan's own postwar constitution, with its renunciation of war in Article 9, is partly a response to this history.
What exams ask
- Why did Japan industrialise and expand so quickly? Link the threat from unequal treaties, the Meiji reforms and the idea of security lines.
- Compare the two wars. Know the Treaty of Shimonoseki (1895) and the Treaty of Portsmouth (1905) and what each gave Japan.
- Japan versus Western imperialism. Similar motives of markets, resources and prestige, but Japan expanded into neighbouring Asia and justified it partly with pan-Asian slogans.
- Turning points. 1895 Taiwan, 1910 Korea, 1931 Manchuria, 1937 total war with China, 1941 the Pacific War.
- Significance. The first non-Western imperial power, a challenge to European dominance in Asia, and a lasting source of historical disputes.
Read next
- Imperialism: What It Was, Why It Happened, What It Left Behind: the overall pattern into which Japan's story fits.
- American Imperialism (1898–1914): the other new power that took colonies in the Pacific at the same time.
- The East India Company: how a trading firm became a ruler in Asia, for comparison with Japan's state-led empire.
- The Abolition of the Slave Trade and Slavery: the forced-labour question in the wider history of empires.
