Trịnh Tráng
Trịnh Tráng succeeded Trịnh Tùng, his father, upon his death in 1623. Tráng ordered Nguyễn Phúc Nguyên to submit to his authority. The order was refused twice. In 1627, Trịnh Tráng sent 150,000 troops southward in an unsuccessful military campaign. The Trịnh were much stronger, with a larger population, economy and army, but they were unable to vanquish the Nguyễn, who had built two defensive stone walls and invested in Portuguese artillery.