西山朝
At that time, Nguyễn Huệ's influence became stronger in northern Vietnam; this made emperor Nguyễn Nhạc of the Tây Sơn dynasty suspect Huệ's loyalty. The relationship between the brothers became tense, eventually leading to battle. Huệ had his army surround Nhạc's capital, at Quy Nhơn citadel, in 1787. Nhạc begged Huệ not to kill him, and they reconciled. In 1788, Lê emperor Lê Chiêu Thống fled to China and asked for military assistance. Qing emperor Qianlong ordered Sun Shiyi to lead the military campaign into Vietnam. The campaign failed, diplomatic relations with Vietnam were normalized, and the Tây Sơn dynasty began to weaken.