In 1782, Trịnh Sâm died and passed the throne to Trịnh Cán. However, Cán was only five years old at the time, the real ruler was Hoàng Ngũ Phúc's adopted son Hoàng Đình Bảo, who was appointed by Sâm as Cán's assistant. A few weeks after Cán was crowned, Trịnh Tông conspired with the Three Prefectures Army (, ) to kill Hoàng Đình Bảo and overthrow Trịnh Cán. However, because Tông was indebted to the army, he couldn't control them. The army then released Lê Duy Kì, son of prince Lê Duy Vĩ who was killed by Trịnh Sâm in 1771, and forced Lê Hiển Tông to appoint Kì as the crown prince.