Trịnh–Nguyễn War
The Trịnh–Nguyễn War lasted from 1627 until 1672. The Trịnh army staged at least seven offensives, all of which failed to capture Phú Xuân. For a time, starting in 1651, the Nguyễn themselves went on the offensive and attacked parts of Trịnh territory. However, the Trịnh, under a new leader, Trịnh Tạc, forced the Nguyễn back by 1655. After one last offensive in 1672, Trịnh Tạc agreed to a truce with the Nguyễn Lord Nguyễn Phúc Tần. The country was effectively divided in two.