As rebels, they conquered Vietnam, overthrowing the imperial Later Lê dynasty and the two rival feudal houses of the Nguyễn in the south and the Trịnh in the north.

Through his work he met and married Nguyễn Thị Đồng (阮氏仝), the only daughter of a rich betel tradesman residing in Tây Sơn village.

[8] Đại Nam chính biên liệt truyện described Nguyễn Huệ as "a cunning man, good at fighting; he has bright penetrating eyes, and always speak in a stentorian voice, everyone fears him.

[9] After 200 years of holding power in southern Vietnam, the government of the Nguyễn Lords had become progressively weaker, due to its poor leadership and internal conflicts.

[11] At the same time, the general of the Nguyễn lords Tống Phước Hiệp (宋福洽) led his troops against Phú Yên, forcing the Tây Sơn army to withdraw.

[11] Recognizing that the temporary ceasefire was unlikely to endure, Nguyễn Nhạc retrained the rebel army, recruited new soldiers, fortified Đồ Bàn fortress, and built new bases, preparing for an attack.

He sent a large army led by his youngest brother Nguyễn Lữ to launch a sudden attack against Gia Định (now called Ho Chi Minh City) by sea.

His success was short-lived, however, when an army loyal to the Nguyễn Lords and led by a man named Đỗ Thanh Nhơn rose against him in Đông Sơn.

A fleet with twenty thousand men under Chao Fa Krom Luang Thepharirak was dispatched to attack and recapture Saigon for Nguyễn Ánh.

[13][14] Siamese troops defeated Tây Sơn army and captured several places including Rạch Giá, Trấn Giang (Cần Thơ), Ba Thắc (Srok Pra-sak, Sóc Trăng), Trà Ôn, Sa Đéc, Mân Thít (or Mang thít, Man Thiết), and controlled Hà Tiên, An Giang and Vĩnh Long.

The governor of Phú Xuân, Phạm Ngô Cầu, was a venal and superstitious coward, he was at odds with his assistant, Hoàng Đình Thể.

Tây Sơn army attacked war elephants with arquebuses, finally, they captured Thăng Long (modern Hanoi) successfully.

Huệ was warmly welcomed by Lê Hiển Tông, and received the position Nguyên-soái (元帥 "supreme commander") noble title Uy-quốc-công (威國公).

Huệ received the title Bắc Bình Vương (北平王 "King of Northern Conquering"[note 3]), the area north to Hải Vân was given as his fief.

The main forces of Gia Định was called back to support Nhạc, but was defeated in Phú Yên, its commander Đặng Văn Chân surrendered to Huệ.

In order to gain popularity among Northern Vietnamese, Nhậm install Lê Duy Cận as giám quốc ("Prince Regent").

[16] His mother, Empress Dowager Mẫn, fled to Longzhou, called for help from Qing China in order to restore Lê dynasty.

In the next day, Nguyễn Huệ erected an altar on a hill south of Phú Xuân and proclaimed himself Emperor Quang Trung, in effect abolishing the Lê dynasty.

In the fierce 4-day battle, most of Chinese soldiers were unprepared, they were disastrously defeated by the Tây Sơn army in Ngọc Hồi and Đống Đa (part of modern Hanoi).

[20] The official system of Tây Sơn dynasty was not mentioned in official records, but we could find several names of official positions in history records, such as tam công (三公), tam thiếu (三少), Đại-chủng-tể (大冢宰), Đại-tư-đồ (大司徒), Đại-tư-khấu (大司寇), Đại-tư-mã (大司馬), Đại-tư-không (大司空), Đại-tư-cối (大司會), Đại-tư-lệ (大司隸), Thái-úy (太尉), Đại-tổng-quản (大總管), Đại-đổng-lý (大董理), Đại-đô-đốc (大都督), Đại-đô-hộ (大都護), Trung-thư-sảnh (中書廳), Trung-thư-lệnh (中書令), Đại-học-sĩ (大學士), Hiệp-biện đại-học-sĩ (協辦大學士), Thị-trung ngự-sử (侍中御史), Lục-bộ thượng-thư (六部尚書), Tả-hữu đồng-nghị (左右同議), Tả-hữu phụng-nghị (左右奉議), Thị-lang (侍郎), Tư-vụ (司務), Hàn-lâm (翰林), etc.

Then, the army invaded Kingdom of Vientiane; king Nanthasen fled, Tây Sơn marched west till the border of Siam.

The victorious army attacked Bảo Lộc, captured Lê Duy Chỉ, Nùng Phúc Tấn, Hoàng Văn Đồng, and had them executed.

Quang Trung also requested for exemption from customs duties, and established a yá háng (牙行, broker house in ancient China) in Nanning, they were both agreed by the Qianlong Emperor.

[7] Nguyễn Huệ was resentful, trained his army, built large warships and waited for an opportunity to take revenge on China.

[29] With the support of Tây Sơn dynasty, the number of Chinese pirates grew rapidly, they were able to block sea routes, and harassed the coastlines of China.

His will instructed that he be buried within a month; all ministers and generals should be united as one to assist the Crown Prince; and move the capital to Phượng Hoàng trung đô as soon as possible.

Nguyễn Quang Toản built a fake tomb in Linh Đường (苓塘, a place in modern Thanh Trì District) for him.

In the oration, the Qianlong Emperor wrote: "(You have) blessed (me) and pledged loyalty (to me) in the southernmost, (so I) approved you to attend (my) imperial court; (now you) lie at rest beside the West Lake, (you are) nostalgic for (the good old days in) my palace till death."

A Chinese official was sent to Linh Đường to pay condolences, and granted Nguyễn Quang Toản the title An Nam quốc vương ("King of Annam").

[citation needed] On 6 February 2018 the Vietnam People's Navy commissioned the Quang Trung a Gepard-class frigate currently in service with the 4th Regional Command.