By 1771, the nation had been divided for over a hundred years. The Outer Region (Đàng Ngoài) suffered from famine, corrupt mandarins, and taxes heavy as mountains.
The Inner Region (Đàng Trong) saw the Nguyễn Lords constantly fighting Siam, while the people were exploited to the bone.
Amidst this desperation, in the Tây Sơn uplands (modern-day Bình Định), three brothers of the Nguyễn clan arose like a tempest. The eldest, Nguyễn Nhạc; the second, Nguyễn Huệ; and the youngest, Nguyễn Lữ.
All three hailed from humble backgrounds teachers, tax collectors, or betel traders but the fire of rebellion ran in their veins. In 1771, under the banner of "taking from the rich to give to the poor," they marched their army to seize Quy Nhơn Prefecture. In just a few months, the entire Bình Định region fell to the Tây Sơn.
Nguyễn Huệ the man later known as Quang Trung was only 19 years old, yet he struck terror into the Nguyễn Lords' generals:
"I fight not for the throne, I fight for the starving common people!"
In 1773, the Trịnh army advanced from the North to attack the Nguyễn Lords. Nguyễn Huệ seized the opportunity to launch a surprise attack on Phú Xuân, then swiftly marched his army into Gia Định, annihilating the Nguyễn Lords in the Inner Region in just a few months. In 1778, the last Nguyễn Lord, Nguyễn Phúc Thuần, was captured and beheaded.
By 1785, the nation had only two remaining powers: the Trịnh in the North, and the Tây Sơn in the South.
In 1786, the Trịnh Lord died, and the Trịnh army descended into chaos. King Lê Chiêu Thống sought aid from the Qing army in the North. 290,000 Qing troops marched into Thăng Long, installing Lê Chiêu Thống as a "puppet king."
Hearing the news of the Qing invasion, Nguyễn Huệ ascended the throne immediately at Bân Mountain (Huế), taking the title Quang Trung.
On the 25th day of the 11th lunar month, the year Mậu Thân (1788), Quang Trung rode his elephant, leading 100,000 troops North. In just 40 days, he achieved a miracle that history calls "lightning fast strikes."
On the 30th day of the Lunar New Year, the Tây Sơn army occupied Thăng Long. On the 5th day of the Tết holiday, the year Kỷ Dậu (1789), he utterly destroyed 290,000 Qing troops in the Đống Đa,Ngọc Hồi Battle. The enemy's blood turned the Red River crimson, and their corpses piled up into hills. Quang Trung stood on the Đống Đa mound, pointing North:
"From now on, the Lam Mountain and the Red River belong only to the Việt people!"
The routed Qing army fled home; Emperor Qianlong, pale with fear, had to recognize Quang Trung as the "King of Annam" and seek peace. Between 1789 and 1792, in just four short years, Quang Trung accomplished what no one had dared to do for a hundred years:
He moved the capital to Phượng Hoàng Trung Đô (Nghệ An), planning to build a new national center.
He encouraged the use of Chữ Nôm (Vietnamese demotic script) and translated scriptures into Vietnamese.
He banned officials from gambling, drinking, and exploiting the people.
He opened the North–South Thousand-Mile Road and allotted public land to the poor.
He built the strongest standing army in Southeast Asia at the time.
He once told his generals:
"I fight the enemy so the people can have enough rice and clothes, not so I can sit on the throne!"
But Heaven did not grant the hero a long life. In 1792, Quang Trung suddenly passed away at the age of 40. He left the throne to his ten-year-old son, Nguyễn Quang Toản.
Without Quang Trung, the Tây Sơn quickly declined. In 1802, Nguyễn Ánh (a descendant of the former Nguyễn Lords), with the assistance of French and Siamese forces, defeated the Tây Sơn. Nguyễn Quang Toản was captured and beheaded in Thăng Long.
The Tây Sơn Dynasty collapsed after 24 years (1778-1802). But the Tây Sơn flame never died out in the hearts of the people. It is still passed down that:
"When the nation is in despair, there will once again be three brothers in common clothes rising from the Bình Định mountains,
wielding swords, riding elephants, defeating foreign invaders, and restoring rice and warmth to the people."
Thus, Tây Sơn was not just a dynasty,
but the symbol of the strength of the Vietnamese peasantry when pushed to the wall, the farmers transformed into the greatest soldiers in history.