section_path: History/Establishment of the Republic and World War II
section_name: Establishment of the Republic and World War II
paragraph_text: Establishment of the Republic and World War II
  
  On 1 January 1912, the Republic of China was established, and Sun Yat-sen of the Kuomintang (KMT) was proclaimed provisional president. In March 1912, the presidency was given to Yuan Shikai, a former Qing general who in 1915 proclaimed himself Emperor of China. In the face of popular condemnation and opposition from his own Beiyang Army, he was forced to abdicate and re-establish the republic in 1916. After Yuan Shikai's death in 1916, China was politically fragmented. Its Beijing-based government was internationally recognized but virtually powerless; regional warlords controlled most of its territory. During this period, China participated in World War I and saw a far-reaching popular uprising (the May Fourth Movement).
  
  In the late 1920s, the Kuomintang under Chiang Kai-shek was able to reunify the country under its own control with a series of deft military and political maneuverings known collectively as the Northern Expedition. The Kuomintang moved the nation's capital to Nanjing and implemented "political tutelage", an intermediate stage of political development outlined in Sun Yat-sen's Three Principles of the People program for transforming China into a modern democratic state. The Kuomintang briefly allied with the Chinese Communist Party (CCP) during the Northern Expedition, though the alliance broke down in 1927 after Chiang violently suppressed the CCP and other leftists in Shanghai, marking the beginning of the Chinese Civil War. The CCP declared areas of the country as the Chinese Soviet Republic (Jiangxi Soviet) in November 1931 in Ruijin, Jiangxi. The Jiangxi Soviet was wiped out by the KMT armies in 1934, leading the CCP to initiate the Long March and relocate to Yan'an in Shaanxi. It would be the base of the communists before major combat in the Chinese Civil War ended in 1949.
  
  In 1931, Japan invaded and occupied Manchuria. Japan invaded other parts of China in 1937, precipitating the Second Sino-Japanese War (1937–1945), a theater of World War II. The war forced an uneasy alliance between the Kuomintang and the CCP. Japanese forces committed numerous war atrocities against the civilian population; as many as 20 million Chinese civilians died. An estimated 40,000 to 300,000 Chinese were massacred in Nanjing alone during the Japanese occupation. China, along with the UK, the United States, and the Soviet Union, were recognized as the Allied " Big Four " in the Declaration by United Nations. Along with the other three great powers, China was one of the four major Allies of World War II, and was later considered one of the primary victors in the war. After the surrender of Japan in 1945, Taiwan, along with the Penghu, were handed over to Chinese control; however, the validity of this handover is controversial.