Toghon's land army, leaving Vạn Kiếp on 8 April, was ambushed at the Nội Bàng pass on 11 April and harassed all the way through Đơn Kỷ and Lộc Châu; hungry and wounded, it reached Siming on 19 April.
Battle
Ambush at Nội Bàng and the Yuan retreat through Lạng Sơn
- 11 April 1288
- Southeast Asia