In 1781, when Đỗ Thanh Nhơn was assassinated by his own leader, Nguyễn Ánh, Võ Tánh and his brother, Võ Nhàn, revolted and occupied Hóc Môn, a village on the northern outskirts of Saigon.
Meanwhile, Nguyễn Ánh was badly defeated at the Battle of Rạch Gầm-Xoài Mút and fled to Siam which made the Kiến Hòa army the only rival of the Tây Sơn in the Gia Định region.