Japan's transformation into an imperial power was the result of its victory as a member of the Allied Powers in World War I, its growth as a westernized industrial nation and the gain of territory achieved during its wars with Russia and China between 1894 and 1905. Japan was also granted control of the Shandong Peninsula in China in exchange for helping the British during World War I. Prior to the outbreak of World War II, Japan invaded and occupied Manchuria, an act which further established Japanese territorial expansion and gained the country control of a Chinese province rich in resources.
The growth of the Japanese population from 35 million to 70 million in little more than a half century, coupled with the development of an emperor-based and militaristic centralized state government were also factors contributing to the nation's transformation into an imperial power. The Empire of Japan was established in 1868 by the Japanese Emperor Meiji, and it effectively ended the feudal system of provincial control by local shogun rulers.
The Japanese occupation of Manchuria in 1931 and the establishment of a Japanese-controlled region renamed "Manchukuo" was condemned by Western powers as an act of war. The League of Nations, the intergovernmental peace-keeping organization at that time, proved to be ineffective in achieving a Japanese withdrawal from the region. The League's only real persuasive tool lay in economic sanctions, an approach which had little affect on the Japanese who were already suffering the effects of the worldwide depression taking place at the time. Further Japanese expansions occurred in 1932 with the attack on the city of Shanghai, the start of the Second Sino-Japanese War in 1937 and the empire's invasion of French colonies in Indochina in 1940.