The Battle of Hainan Island occurred in 1950, during the final phase of the Chinese Civil War. The People's Republic of China (PRC) conducted an amphibious assault on Hainan Island on 16 April, assisted by the Hainan communist movement which controlled much of the island's interior, while the Republic of China (ROC) controlled the coast; their forces were concentrated in the north near Haikou and were forced to retreat south after the landings. The communists secured Hainan's southern cities by the end of the month and declared victory on 1 May.
Background
Hainan communist movement
The Chinese Communist Party (CCP) established a branch on Hainan in 1926. Lines of communication between the branch and the CCP leadership were tenuous from the beginning, resulting in the Hainan communist movement developing independently and operating with minimal outside support. The Hainan communists were hard hit by the ROC's repression that followed the end of the First United Front. The Hainan communists were nearly destroyed due to the confined geography of the island; like their mainland counterparts, the few survivors abandoned the urban coast for the rural interior. In 1929, Wang Wenming, leader of the Hainan communists, named Feng Baiju as his successor.
The communists and ROC created a Second United Front in response to Japanese aggression; formal arrangements for Hainan were only made in 1938 after the start of the Second Sino-Japanese War. The Hainan communists were further isolated by the Japanese invasion of the island in 1939 – they had little communication, and no radio contact, with the CCP leadership until the end of the war. Limited hostilities between the Hainan communists and ROC resumed in 1940. The Hainan communists formed a militia called the Hainan Independent Column (HIC). The ROC meanwhile alienated the indigenous Hlai people of the southern interior mountains by occupying Hlai territory and demanding materiel support. In July 1943, the Hlai – led by Wang Guoxing and Wang Yujin – attacked the ROC in the Baisha Uprising. The Hlai were crushed and suffered ROC reprisals. Wang Guoxing and Wang Yujin survived. On Wang Yujin's suggestion, the Hlai formed an alliance with the communists, who were based in the northern interior. The communists relied heavily on the Hlai for survival, and their main base shifted south to Wuzhishan in 1943–1944.
The civil war intensified after the end of the Second World War in 1945. On Hainan, the ROC left Hlai territory and reestablished themselves along the coast. The Hainan communists used access to Hlai territory to grow within the ROC blockade. Maintaining communications with the mainland CCP remained difficult. CCP orders to abandon the island in 1946 were rejected by the Hainan communists, who spent the years following the Japanese withdrawal building popular support.
Communist preparations
By late 1949, the PRC was looking forward to finishing the war by capturing the islands constituting the ROC's remaining strongholds. These tasks were difficult as the ROC retained superior naval and air forces; the communist navy only began to form in the summer with the capture of ROC ships. The PRC was unprepared; the invasions of the islands of Kinmen in October and Dengbu in November failed. The invasion of Hainan was deferred. In January 1950, Mao Zedong approved the invasion while in the Soviet Union for a state visit; he likely sought a victory to impress his hosts.
The Fourth Field Army of the People's Liberation Army (PLA) was tasked with the invasion. It was deployed to the Leizhou Peninsula in Guangdong, across the Qiongzhou Strait from Hainan. The subordinate 15th Corps, led by General Deng Hua, would participate in the cross-strait invasion. The defeat at Kinmen led to greater preparations.
Planning for the invasion occurred in the winter of 1949–1950. Wang Guoxing and Ma Baishan travelled through ROC-held territory to communist-held Beijing in the fall of 1949; they were in the city for the proclamation of the People's Republic of China. The Hainan delegation conferred with the PRC's military leadership before returning south in the wake of the PRC's advance. They arrived in time to attend the final invasion planning meeting in February 1950 which was attended by both Hainanese and PLA officers. Ma relayed Feng's suggestion that the attack from the north be made of pincer movements rather than a frontal assault on – and battle of attrition for – Haikou.