Sun Shiyi
210px-General Nie Shicheng
Sun Shiyi (1720 – 1796)
Some attributes
First Name: Sun Shiyi
Second Position: Viceroy of Liangguang and Liangjiang
Third Nationality: Han Chinese
Other attributes
Fourth Allegiance: Qing Dynasty
Fifth Born: 1720
Sixth Died: 1796 (aged 76)

Sun Shiyi (simplified Chinese: 孙士毅; traditional Chinese: 孫士毅; pinyin: Sūn Shìyì; Wade–Giles: Sun Shih-i; 1720 – 1796), courtesy name Zhizhi (智冶), pseudonym Bushan (補山), was an official of the Qing Dynasty who served as the Viceroy of Liangguang and of Liangjiang during the reign of the Qianlong Emperor.

A native of Renhe (present-day Yuhang District, Zhejiang), as a youth, Sun was devoted to study and was said to have prevented drowsiness by knocking his head against a wall. Awarded a jinshi degree in the imperial examination in 1761, he was secretary to Fuheng during his Burmese expedition, and in 1770 had risen to be Treasurer of Guangxi, when he was cashiered on false charges, and orders were given to confiscate his property.

Struck with the fact that nothing was found to confiscate, the Qianlong Emperor re-employed him, and in 1788, as Viceroy of Liangguang, he invaded Annam with 200,000-290,000 men, which recruited from Guangdong, Guangxi, Yunnan and Guizhou, and placed on the throne Le Chieu Thong, who had been driven out be his Minister Nguyen Hue. The Vietnamese retreated to Tam Điệp mountains. From there they sent a messenger to Phú Xuân (modern Huế), appealing to Nguyễn Huệ for help. Nguyễn Huệ was proclaimed the Quang Trung Emperor, and recruited 100,000 volunteers in Nghệ An Province.

Then he gathered his forces in the countryside around Thăng Long which had been taken by the Qing armies. He launched a surprise attack against the Qing forces while they were celebrating the Chinese New Year festival of the year 1789. Most of Chinese soldiers were unprepared, so were disastrously defeated by the Tây Sơn army in Ngọc Hồi and Đống Đa (part of modern Hanoi). Chinese generals Xu Shiheng, Shang Weisheng, Zhang Chaolong and Cen Yidong were killed in action. Nguyễn Huệ recaptured Thăng Long, and Sun fled back to China. Many Chinese soldiers and porters drowned crossing the Red River.

After this defeat, Sun was sent to Sichuan to supply the army fighting in Tibet, into which country he advanced over terrible mountains as far as Chamdo. In 1792, on the conclusion of the war with Nepal, the suppression of the White Lotus Rebellion occupied his last days. His physical powers were marvellous, and he required hardly any sleep. He was a great collector of ancient inscriptions. He was ennobled as Duke Mouyong of the First Class (一等謀勇公).