Chinese Civil War in the context of "Second Sino-Japanese War"

Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main island of Taiwan, also known as Formosa, lies between the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the northeast, and the Philippines to the south. It has an area of 35,808 square kilometres (13,826 square miles), with mountain ranges dominating the eastern two-thirds and plains in the western third, where its highly urbanized population is concentrated. The combined territories under ROC control consist of 168 islands in total covering 36,193 square kilometres (13,974 square miles). The largest metropolitan area is formed by Taipei (the capital), New Taipei City, and Keelung. With around 23.9 million inhabitants, Taiwan is among the most densely populated countries.

Taiwan has been settled for at least 25,000 years. Ancestors of Taiwanese indigenous peoples settled the island around 6,000 years ago. In the 17th century, large-scale Han Chinese immigration began under Dutch colonial rule and continued under the Kingdom of Tungning, the first predominantly Han Chinese state in Taiwanese history. The island was annexed in 1683 by the Qing dynasty and ceded to the Empire of Japan in 1895. The Republic of China, which had overthrown the Qing in 1912 under the leadership of Sun Yat-sen, assumed control following the surrender of Japan in World War II. But with the loss of mainland China to the Communists in the Chinese Civil War, the government moved to Taiwan in 1949 under the Kuomintang (KMT).

"Mainland China" is a geopolitical term defined as the territory under direct administration of the People's Republic of China (PRC) in the aftermath of the Chinese Civil War. In addition to the geographical mainland, the geopolitical sense of the term includes islands such as Hainan, Chongming, and Zhoushan. It is also important to note that the terms "the Chinese mainland" or "the mainland of China" are preferred by explicitly pro-Beijing bodies, while the more common term in the English-speaking world and in Taiwan, Hong Kong, and Macau is "mainland China".

By convention, territories covered by the term exclude:

The Republic of China (ROC) was established on 1 January 1912 as a sovereign state in mainland China following the 1911 Revolution, which overthrew the Manchu-led Qing dynasty and ended China's imperial history. From 1927, the Kuomintang (KMT) reunified the country and initially ruled it as a one-party state with Nanjing as the national capital. In 1949, the KMT-led government was defeated in the Chinese Civil War and lost control of the mainland to the Chinese Communist Party (CCP). The CCP established the People's Republic of China (PRC) while the ROC was forced to retreat to Taiwan; the ROC retains control over the Taiwan Area, and its political status remains disputed. The ROC is recorded as a founding member of both the League of Nations and the United Nations, and previously held a permanent seat on the United Nations Security Council until 1971, when the PRC took the seat of China from the ROC in the United Nations General Assembly Resolution 2758. It was also a member of the Universal Postal Union and the International Olympic Committee. The ROC 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, the ROC's founder and provisional president of the new republic, following the success of the 1911 Revolution. 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. Yuan's 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. When Yuan died in 1916, the country fragmented between local commanders of the Beiyang Army, beginning the Warlord Era defined by decentralized conflicts between rival cliques. At times, the most powerful of these cliques used their control of Beijing to assert claims to govern the entire Republic.

The Communist Party of China (CPC), commonly known as the Chinese Communist Party (CCP), is the founding and ruling party of the People's Republic of China (PRC). Founded in 1921, the CCP won the Chinese Civil War against the Kuomintang and proclaimed the establishment of the PRC under the chairmanship of Mao Zedong in October 1949. The CCP has since governed China and has had sole control over the country's armed forces and law enforcement. As of 2024, the CCP has more than 100 million members, making it the second largest political party by membership in the world.

In 1921, Chen Duxiu and Li Dazhao founded the CCP with the help of the Far Eastern Bureau of the Russian Communist Party (Bolsheviks) and Far Eastern Bureau of the Communist International. Although the CCP aligned with the Kuomintang (KMT) during its initial years, the rise of the KMT's right-wing under the leadership of Chiang Kai-shek and subsequent massacres of tens of thousands of CCP members resulted in a split and a prolonged civil war between the CCP and KMT. During the next ten years of guerrilla warfare, Mao Zedong rose to become the most influential figure in the CCP and the party established a strong base among the rural peasantry with its land reform policies. Support for the CCP continued to grow throughout the Second Sino-Japanese War. After the Japanese surrender in 1945, the CCP emerged triumphant in the communist revolution against the Nationalist government. The CCP established the People's Republic of China on 1 October 1949 and the remnants of the Nationalist government retreated to Taiwan shortly after.

Following their defeat in the Chinese Civil War, the remnants of the Nationalist government of the Republic of China (ROC), alongside many refugees, retreated to the island of Taiwan (Formosa) beginning on December 7, 1949. The exodus is sometimes called the Great Retreat (Chinese: 大撤退) in Taiwan. The Nationalist Kuomintang party (KMT), its officers, and approximately 2 million ROC troops took part in the retreat, in addition to many civilians and refugees, fleeing the advance of the People's Liberation Army (PLA) of the Chinese Communist Party (CCP). The CCP, who now effectively controlled most of mainland China, spent the subsequent years purging any remnant Nationalist agents in western and southern China, solidifying the rule of the newly established People's Republic of China (PRC).

ROC troops mostly fled to Taiwan from provinces in southern China, in particular Sichuan Province, where the last stand of the ROC's main army took place. The flight to Taiwan took place over four months after Mao Zedong had proclaimed the founding of the PRC in Beijing on October 1, 1949. The island of Taiwan remained part of Japan during the occupation until Japan severed its territorial claims in the Treaty of San Francisco, which came into effect in 1952. In addition, some of the ROC troops in Yunnan also fled to Burma, where the insurgency lasted until 1961.

The Kuomintang (KMT) is a major political party in the Republic of China (Taiwan). It was the sole ruling party of the country during its rule from 1927 to 1949 in Mainland China until its relocation to Taiwan, and in Taiwan ruled under martial law until 1987. The KMT is a centre-right to right-wing party and the largest in the Pan-Blue Coalition, one of the two main political groups in Taiwan. Its primary rival is the Democratic Progressive Party (DPP), the largest party in the Pan-Green Coalition. As of 2025, the KMT is the largest single party in the Legislative Yuan and is chaired by Cheng Li-wun.

The party was founded by Sun Yat-sen in 1894 in Honolulu, Hawaii, as the Revive China Society. He reformed the party in 1919 in the Shanghai French Concession under its current name. From 1926 to 1928, the KMT under Chiang Kai-shek successfully unified China in the Northern Expedition against regional warlords, leading to the fall of the Beiyang government. After initially allying with the Chinese Communist Party (CCP) in the First United Front, the party under Chiang purged communist members. It was the sole ruling party of China from 1928 to 1949 but gradually lost control while fighting the Empire of Japan in the Second Sino-Japanese War and the CCP in the Chinese Civil War. In December 1949, the Kuomintang retreated to Taiwan following its defeat by the communists.

Shanghai is a direct-administered municipality and the most populous urban area in China. The city is located on the Chinese shoreline on the southern estuary of the Yangtze River, with the Huangpu River flowing through it. The population of the city proper is the second largest in the world with around 24.87 million inhabitants in 2023, while the urban area is the most populous in China, with 29.87 million residents. As of 2022, the Greater Shanghai metropolitan area was estimated to produce a gross metropolitan product (nominal) of nearly 13 trillion RMB ($1.9 trillion). Shanghai is one of the world's major centers for finance, business and economics, research, science and technology, manufacturing, transportation, tourism, and culture. The Port of Shanghai is the world's busiest container port.

Originally a fishing village and market town, Shanghai grew to global prominence in the 19th century due to domestic and foreign trade and its favorable port location. The city was one of five treaty ports forced to open to trade with the Europeans after the First Opium War, with the Shanghai International Settlement and French Concession subsequently established. The city became a primary commercial and financial hub of Asia in the 1930s. During the Second World War, it was the site of the Battle of Shanghai. This was followed by the Chinese Civil War with the Communists taking over the city and most of the mainland. During the Cold War, trade was mostly limited to other socialist countries in the Eastern Bloc, causing the city's global influence to decline.