Answer
Trịnh house, the northern powerhouse ruling Vietnam since the early 16th century, fell to the might of Quang Trung's Tay Son army in 1786. Led by the brilliant military strategist, Quang Trung launched a surprise attack during the Tet holiday, swiftly capturing the Trịnh capital of Thăng Long (present-day Hanoi), ending their dominance, and paving the way for the reunification of Vietnam.