The May Thirtieth Movement (simplified Chinese: 五卅运动; traditional Chinese: 五卅運動; pinyin: Wǔsà Yùndòng) was a major labor and anti-imperialist movement during the middle-period of the Republic of China era. It began when Shanghai Municipal Police officers opened fire on Chinese protesters in Shanghai's International Settlement on May 30, 1925. The shootings sparked international censure and nationwide anti-foreign demonstrations and riots.
In the aftermath of 1924's Second Zhili–Fengtian War China found itself in the midst of one of the most destructive periods of turmoil since 1911. The war had involved every major urban area in China, and badly damaged the rural infrastructure. As a result of the conflict the Zhili-controlled government, backed by varied Euro-American business interests, was ousted from power by the pro-Japanese warlord Zhang Zuolin, who installed a government led by the generally unpopular statesman Duan Qirui in November 1924. Though victorious, the war left Zhang's central government bankrupt and Duan exercised little authority outside Beijing. Authority in the north of the country was divided between Zhang and Feng Yuxiang, a Soviet Union-backed warlord, and public support for the northern militarists soon hit an all-time low, with southerners openly disparaging provincial governors as junfa (warlords). With his monarchist leanings and strong base in conservative Manchuria, Zhang represented the far right in Chinese politics and could claim few supporters. Meanwhile, the KMT (Nationalist) and Communist parties (allied as the First United Front) were running a diplomatically unrecognized Soviet-backed administration in the southern province of Guangdong.