At its 1942 peak, Japan's empire governed over a fifth of humanity
Within half a century of beating Qing China in 1895, Japan had built one of history's largest empires. By 1942 it controlled about 8.5 million square kilometres, and by 1943 some 463 million people lived under its rule. Defeat in 1945 dismantled it almost overnight.
Expansion began close to home. In the early Meiji era Japan tightened its grip on Hokkaido, the Ryukyu, Bonin and Kuril islands. Western powers were scrambling for influence in East Asia, and the modernising Meiji government wanted a place among them; officials also saw colonies in Korea and Manchuria as an outlet for a fast-growing population. In 1876 Japan used gunboat diplomacy to force an unequal treaty on Korea's Joseon court, opening three ports and granting Japanese citizens immunity from local law, much as Western powers had once imposed on Japan.
Wars then delivered territory. Victory over China in 1895 brought Taiwan, which Japan set out to make a showcase colony through modern infrastructure and industry alongside forced assimilation. Defeating Russia in 1904 and 1905 yielded southern Sakhalin, renamed Karafuto, the Liaodong lease and the South Manchuria Railway. Korea became a protectorate in 1905 and was annexed in 1910 as Chōsen, remaining under Japan until 15 August 1945; in 1965 both Japan and South Korea declared the treaties void. Entering the First World War against Germany, Japan seized its Pacific islands, later governed under a League of Nations mandate and fortified in the 1930s as what the navy called unsinkable aircraft carriers.
In 1931 officers of the Kwantung Army staged the Mukden Incident as a pretext to invade Manchuria. The puppet state of Manchukuo followed, with Puyi, the last Chinese emperor, installed as a figurehead. Its heavily state-directed economy grew so fast that by the late 1930s its steel output surpassed Japan's own. Puppet regimes became a template, and from 1940 the conquests were branded the Greater East Asia Co-Prosperity Sphere, eventually stretching across much of China, Southeast Asia and New Guinea.
The expansion was aggressive and accompanied by war crimes that killed millions. In 1939 Soviet and Mongolian troops defeated the Kwantung Army at Khalkhin Gol, and in August 1945 the Soviet Union invaded Manchukuo. After surrender, Tokyo's rule shrank to the home islands; the Soviets annexed Karafuto, and the United States returned the Nanpō and Ryūkyū islands in 1968 and 1972.
Source: Japanese colonial empire
