Nguyễn Huệ made a surprise and fast attack against Chinese forces during the New Year holiday. They reached Thăng Long in the night of 3 January of the next lunar year (28 January 1789). In the fierce 4-day battle, most of Chinese soldiers were unprepared, they were disastrously defeated by the Tây Sơn army in Ngọc Hồi and Đống Đa (part of modern Hanoi). Qing generals Xu Shiheng, Shang Weisheng, Zhang Chaolong and Cen Yidong were killed in action. Many Chinese soldiers and porters were killed in action, or drowned while crossing the Red River. According to "Draft History of Qing", over half number of Chinese soldiers died in the battle. Sun Shiyi, the commander-in-chief of Chinese army, abandoned his army, fled for his life back to China with several soldiers. Lê Chiêu Tông also fled to China. Huệ marched into Thăng Long, his clothes was blackened by gunpowder. Tây Sơn army marched further north after the battle; they reached Lạng Sơn, and threatened to march across the border to arrest Lê Chiêu Thống.