 The retreat, which threw away the gains of the February Lạng Sơn Campaign, was ordered by Lieutenant-Colonel Paul Gustave Herbinger, the acting commander of the 2nd Brigade, less than a week after General François de Négrier's defeat at the Battle of Bang Bo (24 March 1885).General Louis Brière de l'Isle, the commander-in-chief of French forces in Tonkin, was in Hanoi city at the time, and was planning to shift his headquarters to Hưng Hóa, to supervise a planned offensive against the Yunnan Army around Tuyên Quang.Brière de l'Isle concluded that the Red River Delta was in jeopardy and fired off a telegram on the evening of 28 March to the French government, warning that the Tonkin Expeditionary Corps faced disaster unless it was immediately reinforced