Republic of China (1912–1949)

The Republic of China established its governance over Mainland China on 1 January 1912 following the Xinhai Revolution, which overthrew the Manchu-led Qing dynasty and ended China's imperial history. The Beiyang government in Beijing was the internationally recognized government of the ROC from 1912 to 1928, with regional warlords occupying parts of the country after the death of Beiyang leader Yuan Shikai in 1916. In 1926, the Kuomintang (KMT) launched the , which eventually reunified the country in 1928. The KMT established the Nationalist government and governed the ROC as a one-party state with Nanjing as the capital. In 1949, the KMT was defeated in the Chinese Civil War by the Chinese Communist Party (CCP) and the ROC government retreated to Taiwan, where it remains to this date. The ROC is recorded as a founding member of both the League of Nations and the United Nations. It claimed 11.4 million km (4.4 million sq mi) of territory, and its population of 541 million in 1949 made it the most populous country in the world.

The Republic of China was officially proclaimed on 1 January 1912 by revolutionaries under Sun Yat-sen, who became provisional president of the new republic. Puyi, the final Qing emperor, abdicated on 12 February 1912. Sun served briefly before handing the presidency to Yuan Shikai, the leader of the Beiyang Army. The Beiyang government quickly became authoritarian and exerted military power over the administration. In 1915, Yuan attempted to replace the Republic with his own imperial dynasty until popular unrest forced him to back down. After he died in 1916, the country fragmented between local commanders of the Beiyang Army, commencing the Warlord Era defined by decentralized conflicts between rival cliques.

Meanwhile, the KMT under Sun attempted multiple times to establish a rival government in Guangzhou, eventually taking the city with help from the Soviet Union under the condition that the KMT form the First United Front with the CCP in order to go about reunifying China. Sun's death in 1925 precipitated a power struggle that eventually resulted in the rise of General Chiang Kai-shek to KMT chairmanship. By 1927, Chiang felt secure enough to end the alliance with the Soviets and purged the Communists before completing the to achieve Sun's goal in 1928. Chiang subsequently ruled the country as a one-party state under the Dang Guo system, receiving international recognition as the representative of China.

While there was relative prosperity during the Nanjing decade (1927–1937), the ROC faced internal and external threats. The severely weakened CCP gradually rebuilt its strength by organizing peasants in the countryside. Surviving warlords who resented Chiang's consolidation of power led several uprisings, most significantly the Central Plains War. In 1931, Japan invaded Manchuria, followed by a full-scale invasion of China in 1937. World War II devastated the ROC, leading to enormous loss of life and material destruction. Japan surrendered in September 1945 and Taiwan was placed under Chinese administration. Civil war resumed, and the CCP's People's Liberation Army began to gain the upper hand in 1948. The People's Republic of China was proclaimed in October 1949 amid the ROC's exodus to Taiwan.