The Tây Sơn's invasion and sudden withdrawal caused a large power vacuum in the North. Trịnh Sâm's younger brother Trịnh Lệ with the support of Dương Trọng Tế marched into Thăng Long and forced Chiêu Thống to grant him the title Viceroy, which would make him a Trịnh lord. Emperor Chiêu Thống did not want to reinstall Trịnh lords, thus he rejected Lệ's request. At the same time, Trịnh Bồng, son of Trịnh Giang, also marched into Thăng Long. Dương Trọng Tế thought Trịnh Lệ was unpopular and defected to Bồng's side, helped him defeated Trịnh Lệ. Famous generals Hoàng Phùng Cơ and Đinh Tích Nhưỡng also joined Trịnh Bồng's faction and pressured Chiêu Thống to grant him the title prince, the emperor reluctantly agreed. He then sent a request to Nguyễn Hữu Chỉnh, who had raised a considerable army in his hometown, to come and aid the emperor once again. Nguyễn Hữu Chỉnh obeyed and marched north, he defeated Trịnh army in Thanh Hoa Province. Trịnh Bồng heard of the news and withdrew to Gia Lâm District with Dương Trọng Tế, Đinh Tích Nhưỡng and Hoàng Phùng Cơ withdrew to Hải Dương and Sơn Tây respectively. Chiêu Thống set Trịnh's palace on fire.