Nguyễn Nhạc, the eldest of the Tây Sơn brothers, launched the rebellion from the midland region of Gia Lai, where mountain and coastal communities converged. Emerging from a period of profound crisis in southern Việt Nam (Đàng Trong), the movement united Kinh, Thượng, and Hoa populations amid widespread political decay.
Historians note that Nguyễn Nhạc’s local leadership, knowledge of social tensions and ability to mobilize peasants, merchants, mountain tribes, scholars, and village elites enabled the movement to transform from an uprising into an organized force.
While history often highlights Emperor Quang Trung Nguyễn Huệ’s military triumphs at Rạch Gầm-Xoài Mút (1785) and Ngọc Hồi-Đống Đa (1789), and Đông Định Vương Nguyễn Lữ’s consolidation of Gia Định, scholars underscore that the Tây Sơn structure itself would not have formed without Nguyễn Nhạc’s groundwork. His strategy centred on securing bases and controlling trade routes linking the highlands with the plains and the sea, creating durable logistical and political networks.
Between 1776 and 1788, the Tây Sơn movement expanded across territories from Quảng Nam to Bình Thuận. Distinct from many uprisings of its time, it soon embraced a state-building vision.
Nguyễn Nhạc sought not only to dismantle the failing regime but to establish a new political order, positioning himself as the pioneer of the Tây Sơn’s early institutional framework.
A defining moment came when he selected Đồ Bàn Citadel as the movement’s centre of power. Construction began in 1776, and by 1778 the stronghold was completed and renamed Hoàng Đế (Emperor) Citadel.
Nguyễn Nhạc then ascended the throne as Emperor Thái Đức, formally founding the Tây Sơn dynasty. Historical records from the Nguyễn dynasty, including Đại Nam nhất thống chí and Đại Nam chính biên liệt truyện, recognize this event as the establishment of a new government asserting its sovereignty.
Modern scholarship views the Emperor Citadel as more than a political seat. Archaeological findings reveal layers of architectural heritage from Champa to the Tây Sơn and later the Nguyễn dynasty, illustrating continuity and transformation across eras.
The citadel’s role as the command centre of the Tây Sơn government lasted more than two decades, during which it became what Associate Professor Dr. Đỗ Bang describes as a “war machine.” From here, Tây Sơn forces defeated Siamese troops, weakened the power of the Nguyễn and Trịnh lords, and connected regions from Gia Định to Thăng Long in the push toward national reunification.
Dr. Đỗ Bang also notes that internal decentralization and limitations in socio-economic policies contributed to the dynasty’s later decline. Yet from today’s perspective in Gia Lai, the Tây Sơn movement is remembered not only for battlefield victories but for its process of political formation rooted in Nguyễn Nhạc’s vision.
The Emperor Citadel, now located in An Nhơn ward, remains a testament to that transformative period, not only as a historic relic but as a symbol of the moment when an uprising became a dynasty. Within this legacy, Emperor Thái Đức Nguyễn Nhạc endures as the figure who opened a defining chapter in Việt Nam’s history.