After a pause for breath at Dong Song to resupply with food and ammunition and to establish a shorter supply line back to Chu across the mountain of Deo Quan, the Tonkin expeditionary corps pressed on towards Lạng Sơn.
Setelah hening sejenak di Dong Song untuk memasok makanan dan amunisi dan membangun jalur suplai yang lebih pendek ke Chu melintasi gunung Deo Quan, korps ekspedisi Tonkin mendesak ke arah Lạng Sơn.