Republic of China (1912–1949) member of United Nations
The Republic of China (ROC) was the government of China from 1912, when it was proclaimed in the 1911 Revolution, until 1949, when it was defeated in the Chinese Civil War and its central government retreated to Taiwan. The People's Republic of China (PRC) succeeded it in the governance of Mainland China, while the ROC remains the government of Taiwan.
The Republic was declared on 1 January 1912 after the 1911 Revolution overthrew the Qing dynasty, the last imperial dynasty of China. Sun Yat-sen, its founder and provisional president, served only briefly before handing over the presidency to Yuan Shikai, the leader of the Beiyang Army. Yuan quickly became authoritarian and used his military power to control the administration, which consequently became known as the "Beiyang government." Yuan even attempted to replace the Republic with his own imperial dynasty until popular unrest forced him to back down. When Yuan died 1916, the country fragmented between the various local commanders the Beiyang Army. This began the Warlord Era of decentralized conflicts between rival warlord cliques. The most powerful of these cliques, notably the Zhili and Fengtian cliques, at times used their control of Beijing to assert claims to govern the entire Republic.
Meanwhile, the Kuomintang (KMT or Nationalists), under the leadership of Sun, attempted multiple times to establish a rival national government in Canton. Sun was finally able to take Canton with the help of weapons, funding, and advisors from the Soviet Union. As a condition of Soviet support, the KMT formed the "First United Front" with the Chinese Communist Party (CCP). CCP members joined the KMT and the two parties cooperated to build a revolutionary base in Canton. Sun planned to use this base to launch a military campaign northwards and reunify the rest of China. Sun's death in 1925 precipitated a power struggle that eventually resulted in the rise of General Chiang Kai-shek to Chairman of the KMT. Thanks to strategic alliances with warlords and help from Soviet military advisors, Chiang was able to lead a successful "Northern Expedition". By 1927, Chiang felt secure enough to end the alliance with the Soviet Union and purged the Communists from the KMT. In 1928, the last major independent warlord pledged allegiance to the Nationalist government in Nanjing.
While there was relative prosperity during the following ten years under Chiang Kai-shek, the Republic of China continued to be destabilized by the Chinese Civil War, revolts by the KMT's warlords allies, and steady territorial encroachments by Japan. Although heavily damaged by the purge, the CCP gradually rebuilt its strength by focusing on organizing peasants in the countryside. Warlords who resented Chiang's attempts to take away their autonomy and incorporate their military units into the National Revolutionary Army repeatedly led devastating uprisings, most significantly the Central Plains War. In 1931, the Japanese invaded Manchuria. They continued a series of smaller territorial encroachments until 1937, when they launched a full-scale invasion of the Republic of China. 
World War II devastated China, leading to enormous loss of life and material destruction. Japanese occupation continued until the surrender of Japan at the end of World War II in 1945. In the aftermath of World War II, civil war resumed between the areas liberated by the Republic of China and those liberated by the Communists. The Communist People's Liberation Army managed to defeat the larger and better-armed National Revolutionary Army due to higher morale and better tactics. In 1949, the ROC repeatedly moved its capital to avoid the Communist advance—first to Guangzhou, followed by Chongqing, Chengdu, and lastly, Taipei. In October 1949, the CCP proclaimed the People's Republic of China. Remnants of the ROC government would hang on in Mainland China until late 1951.
The ROC was a founding member of the League of Nations and later the United Nations (including its Security Council seat) where it maintained until 1971, when the People's Republic of China took over its membership. It was also a member of the Universal Postal Union and the International Olympic Committee. At a population of 541 million in 1949, it was the world's most populous country. Covering 11.4 million square kilometres (4.4 million square miles), it consisted of 35 provinces, 1 special administrative region, 2 regions, 12 special municipalities, 14 leagues, and 4 special banners.
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