Trương Văn Đa joined the Tây Sơn army while he was young and married a daughter of Nguyễn Nhạc.
[1] Nguyễn Huệ retreated from Cochinchina and left Đa in Gia Định (mordern Ho Chi Minh City).
Realizing they would be unable to beat the enemy, Đa retreated to Mang Thít and sent Đặng Văn Chân to Quy Nhơn for help.
There, he joined the Battle of Rạch Gầm-Xoài Mút and defeated Siamese forces.
Đa was later replaced by Phạm Văn Tham and called back to Quy Nhơn.