Taksin, the new king of Siam, launches a war in 1769 to regain control of Cambodia.

The war generally goes against the Nguyen and they are forced to abandon some of the newly conquered lands.

This failure, coupled with heavy taxes and corruption at the local level, causes three brothers from the village of Tay Son to begin a revolt against Lord Nguyen Phúc Thuần.

The Tay Son brothers style themselves as champions of the people.

Over the next year, the revolt gains traction and they win some battles against the Nguyen army units sent to crush their rebellion.

The Tay Son have a great deal of popular support, not only from the poor farmers, but from some of the indigenous highland tribes.

The leader of the three brothers, Nguyen Huệ, is also a very skilled military leader.

Nguyễn Huệ’s stated goal is to end the people's oppression, reunite the country, and restore the power of the Lê emperor in Hanoi.

The Tây Son also promise to remove corrupt officials and redistribute land.

In 1773 the Tay Son capture the port of Qui Nhon, where the merchants, who have suffered under restrictive laws put in place by the Nguyen, give the uprising financial support.