阮岳
Having consolidated their hold on southern Vietnam, the Tây Sơn decided to move north to unify the country. However, the withdrawal of troops from the Gia Dinh garrison weakened them their hold on the south. This was compounded by reports that Nguyễn Nhạc was being attacked near Qui Nhơn by his own brother Nguyễn Huệ, and that more Tây Sơn troops were being evacuated from Gia Dinh by their commander Dang Van Tran in order to aid Nguyễn Nhạc. Sensing Tây Sơn vulnerability in the south, Nguyễn Ánh assembled his forces at home and abroad in preparation for an immediate offensive.