Political parties also became powerful at this time. Previously, the emperor's advisors appointed the Prime Minister, but this changed after the war. During the 20's, the Japanese parliament, called the Diet, was given the privilege of choosing Japan's Prime Minister (p 686, Beers). This change made the government be more conscious of what the Diet, and voters, wanted. More political changes in the 20's included giving all men over the age of 25 the right to vote, the implementation of a national health insurance plan, and the removal of certain labor union restraints (p 686, Beers).
Since Japan lacked natural resources and building space, the military invaded the area of Manchuria in northeastern China in September 1931. After the Prime Minister resigned and army officials assassinated the next, the military organized a Japanese military dictatorship (p 686, Beers). The military takeover was not a violent one, and was not led by a specific leader. The constitution and Diet remained in place, but throughout the 1930's Japan became much like a totalitarian state, but with a group of leaders instead of a single dictator. Critics of the governments were arrested, and students in school were taught to unconditionally obey the emperor and the government.
The League of Nations did not take action against Japan's invasion of China. In 1933, Japan withdrew from the League (p 687, Beers). Japan continued to invade China, easily crushing all opposition. Northern and central China was under Japanese control by 1938 (p 698, Beers). In 1940, Japan became allies with Germany and Italy, who helped Japan fight against the United States during World War II.
