quality:corruption
Usurpation of Mạc Đăng Dung

The degenerated Lê dynasty, which endured under six rulers between 1497 and 1527, in the end was no longer able to maintain control over the northern part of the country, much less the new territories to the south. The weakening of the monarchy created a vacuum that the various noble families of the aristocracy were eager to fill. Soon after Lê Chiêu Tông fled south with the Trịnh and the Nguyễn in 1522, Mạc Đăng Dung proclaimed the Emperor's younger brother, Lê Xuân, as the new Emperor under the name Lê Cung Hoàng. In reality, the new Emperor had no power. Three years after Mạc's forces killed his older brother Lê Chiêu Tông, was pressured from Mạc Đăng Dung, in Bắc Sứ garden, Lê Cung Hoàng hanged himself on 18 June 1527. Mạc Đăng Dung, being a scholar-official who had effectively controlled the Lê for a decade, murdered all the Lê imperial family member then proclaimed himself the new Emperor of Vietnam on 15 June 1527, ending (so he thought) the Lê dynasty (see Mạc dynasty for more details).

Mạc Đăng Dung's seizure of the throne prompted other families of the aristocracy, notably the Nguyễn and Trịnh, to rush to the support of the Lê loyalists. With the usurpation of the throne, the civil war broke out anew. Again the Nguyễn and the Trịnh gathered an army and fought against Mạc Đăng Dung, this time under the leadership of Nguyễn Kim and Trịnh Kiểm. The Trịnh and the Nguyễn were nominally fighting on behalf of the Lê emperor but in reality, for their own power.