The irate Jiaqing rejected to help Nguyễn Quang Toản, and deported his envoy. In 1802, Nguyễn Quang Thùy was sent to attack Lũy Thầy (in present-day Quảng Bình Province). Later, Nguyễn Quang Toản led 30 thousand men marched to Linh River (modern Gianh River) to attack Nguyễn Ánh. Both of their army were utterly beaten. Toản fled to Nghệ An, in there he met Nguyễn Quang Thùy. They fled back to Thăng Long together. Nguyễn Ánh's army marched further north. In June, they captured Thăng Long. Nguyễn Quang Toản fled across the Nhị River (present day Red River) along with Nguyễn Quang Thùy, Nguyễn Quang Thùy, Nguyễn Quang Thiệu (), Nguyễn Văn Dụng (), Nguyễn Văn Tứ and the Empress dowager Bùi Thị Nhạn. In Phượng Nhãn (Lạng Giang), They were captured alive by local villagers. Nguyễn Quang Thùy and Bùi Thị Nhạn committed suicide; the others were transferred to Phú Xuân, and executed by Nguyễn Ánh. According to "Đại Nam thực lục", Nguyễn Quang Toản and his three brothers, Nguyễn Quang Duy (), Nguyễn Quang Thiệu and Nguyễn Quang Bàn (), were executed by slow slicing, then their bodies were dismembered by having five elephants pull the limbs and head ().