The January 28 incident, also called the Shanghai incident, was a weeks-long series of clashes between the Imperial Japanese Army and the Republic of China that occurred in Shanghai's International Settlement in 1932.
In January 1932, a pro-Kuomintang newspaper expressed support for a failed assassination attempt on the Japanese emperor Hirohito, provoking outrage among the Japanese. That same month, a group of Japanese Buddhist monks were assaulted by Chinese factory workers bribed by Japanese major Tanaka Ryukichi, giving the Japanese a pretext for an "incident" in Shanghai that would distract international attention from the Japanese invasion of Manchuria. On 22 January 1932, the Japanese demanded that the Mayor of Shanghai disband anti-Japanese societies and boycott activities, and Japanese residents in the International Settlement called for the Japanese naval forces in Shanghai to take actions to ensure their safety. As rumors spread of an impending Japanese attack, the 19th Route Army moved units closer to Little Tokyo. On 23 January, General Cai Tingkai and his colleagues resolved to resist any possible invasion of Shanghai by the Imperial Japanese Navy.
By 27 January, the Japanese military had concentrated 30 ships and 2,000 troops around the Shanghai shoreline, ostensibly to defend its citizens and property. The Japanese then demanded public condemnation and monetary compensation by the Chinese for any Japanese property damaged in the monk incident, and, while the Shanghai Municipal Council agreed to these terms on 28 January, the unpaid soldiers of the 19th Route Army continued to mass outside the city, possibly bent on looting the wealthy International Settlement.
Shortly before midnight on 28 January, plainclothes Chinese soldiers who had infiltrated the Hongkou district fired on Japanese sailors leaving their headquarters, resulting in 3,000 Japanese sailors being mobilized. The Japanese took over the neighboring district of Zhabei, although they faced fierce resistance from the 19th Route Army. While the foreign concessions were largely untouched by the conflict, the rest of the city was devastated, and Chiang Kai-shek temporarily removed the capital from Nanjing to Luoyang in the event of an expanded Japanese offensive. The foreign powers managed to broker a half-day ceasefire on 12 February, but the Chinese military's refusal to retreat 20 kilometers from the border of the Shanghai concessions led to continued fighting. The Japanese were reinforced to 18,000 troops, while Chiang sent two divisions into the city. On 20 February, Japanese bombardments set the city's commercial and residential districts on fire, and the unsupported Chinese infantry stubbornly resisted the Japanese advance. On 1 March, the IJA 11th Division landed near Liuhe and encircled Shanghai's garrison, forcing the Chinese to abandon the city. The fighting stopped on 3 March, and the two nations signed a ceasefire agreement on 5 May, making Shanghai a demilitarized zone. The 19th Army would be reassigned to battle communists in Fujian, only to rebel and establish the Fujian People's Government; the Japanese general Yoshironi Shirakawa was assassinated by a Korean nationalist less than a month after the ceasefire. The Japanese also established the Shanghai Special Naval Landing Force to maintain a permanent land-based military presence in Shanghai.