The long peace came to an end with the Tây Sơn revolt in the south against Trương Phúc Loan, the regent of the Nguyễn Lord, Nguyễn Phúc Thuần (1765–1777). The Tây Sơn rebellion was looked upon by the Trịnh lord, Trịnh Sâm, as a chance to finally put an end to the Nguyễn rule over the south of Vietnam. Inner struggle among the Nguyễn had put a 12-year-old boy in power. The real ruler was the corrupt regent named Trương Phúc Loan. Using the popular rule of the regent as an excuse for intervention, in 1774, the hundred-year truce was ended and the Trịnh army led by Hoàng Ngũ Phúc attacked.