During the Shanghai Massacre on April 12, 1927, members of the Green Gang, the dominant criminal organization in Shanghai, executed and killed communists.

 　During the Shanghai Massacre on April 12, 1927, members of the Green Gang (Shanghai's dominant criminal organization) executed and killed communists. The Shanghai Massacre marked a bloody break between Chiang Kai-shek and his allies and supporters and the Communist Party. The Shanghai Massacre began before sunrise on April 12, signaled by a bugle call from Chiang Kai-shek's military headquarters. A group of armed Triad members wearing white armbands hunted down union members and Communist Party members.

　In the early hours of April 12, 1927, members of criminal organizations began attacking district offices managed by labor unions in areas like Zhabei, Nanshi, and Pudong. The result was over 300 casualties. On April 13, the labor union organized a mass rally denouncing Chiang Kai-shek, and thousands of workers and students marched to protest at the headquarters of the 26th Army's 2nd Division. Kuomintang soldiers opened fire, killing 100 and wounding many more. Chiang Kai-shek dissolved the Shanghai Provisional Government, the labor unions, and all other organizations under Communist Party control. He reorganized the labor unions under Du Yuecheng, requiring loyalty to the Kuomintang. Over 1,000 Communist Party members were arrested, approximately 300 were executed, and more than 5,000 disappeared.

　Chiang Kai-shek ordered the Kuomintang army and Shanghai criminal organizations to purge communists. The Shanghai Massacre erupted on April 12, 1927, resulting in an estimated 5,000 to 10,000 deaths. Communists were systematically expelled from the Kuomintang government, their influence purged from the state, and millions were executed across China. The Communist side responded by forming the Red Army, leading to an 18-year civil war. By 1928, Chiang Kai-shek unified China, incorporating many warlord forces into the Kuomintang army. The full-scale war between the newly formed Communist Red Army and the Kuomintang intensified in 1931. In 1931, Japan invaded Manchuria, replacing Britain and initiating its imperialist campaign in China. The Sino-Japanese War erupted in 1937, with Japanese forces occupying Shanghai and Nanjing.