In 1786, the Tây Sơn general Nguyễn Huệ led his force to northern Vietnam and destroyed the house of the Trịnh lords [REF].
After learning about actions of Nguyễn Hữu Chỉnh, Nguyễn Huệ sent north a general named Vũ Văn Nhậm with an army to attack Thăng Long (now Hanoi) [REF].