The September 18th Incident, also known as Shenyang Incident, Fengtian Incident, Shengjing Incident, Manchuria Incident, Liutiaohu Incident, etc. , refers to a military conflict and political event that broke out in northeast China on September 193 18. The two sides of the conflict are the Northeast Army of China and the Japanese Kwantung Army. The Japanese army occupied Shenyang on the pretext that China troops bombed the South Manchuria Railway built by Japan. According to the date of the conflict, it was called the September 18th Incident. The next day, the Japanese army invaded Shenyang and successively invaded the three northeastern provinces.

1February 932, the whole northeast fell. Since then, the Japanese puppet Manchukuo regime was established in the northeast of China, and began to enslave and colonize the people in the northeast for 14 years, making more than 30 million compatriots in the northeast suffer from conquered people. After the incident broke out, the contradiction between Japan and China intensified, while the status of the Japanese military war faction rose, and the power of the prime minister and cabinet declined, leading to Japan's full-scale invasion of China. Internationally, this incident is often compared with the parliamentary arson in Nazi Germany.