The Tonkin Expeditionary Corps, under the command of General Louis Brière de l'Isle, defeated the Chinese Guangxi Army and captured the strategically important town of Lạng Sơn in a ten-day campaign mounted under formidable logistical constraints.

On 3 and 4 January 1885, General de Négrier attacked and defeated a substantial detachment of the Guangxi Army that had concentrated around the nearby village of Núi Bop to try to disrupt the French preparations.

It took the French a month to complete their preparations for the campaign, but by the end of January 1885, Brière de l'Isle had assembled an expeditionary column of just under 7,200 troops, accompanied by 4,500 coolies, at Chu.

[4] The Lạng Sơn expeditionary column (colonne expéditionnaire de Lang-Son) was organised around the two brigades originally established by General Millot in January 1885.

[6] Shortly after midnight on 2 February the expeditionary corps set off from Chu, with de Négrier's 2nd Brigade leading the way, and advanced over the mountain of Deo Van to Cao Nhiat without meeting any enemy resistance.

Ordered to capture the 'Great Fort', the key to the Chinese position, with his three French line battalions, Herbinger made an elaborate flank march which exhausted his troops and wasted valuable time.

[8] On 5 February the French assaulted the main complex of forts defending the Chinese entrenched camp at Dong Song, around Ha Hoa.

The French units on Deo Quao easily repelled this attack, but the diversion allowed the Guangxi Army to regroup and make a final stand in front of Lạng Sơn.

[11] 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.

2nd Lieutenant Rene Normand, who fell a month later in the Battle of Bang Bo and whose letters from Tonkin were published after his death, distinguished himself in this action.

The battle was fought in thick fog, allowing the Chinese to mount a dangerous counterattack at one point that nearly swept away part of Giovanninelli's brigade.

[13] On 13 February the French column entered Lạng Sơn, which the Chinese abandoned after fighting a token rearguard action at the nearby village of Ky Lua.

In compliment to their performance at Bac Vie, Brière de l'Isle gave Giovanninelli's Turcos and marine infantry the honour of leading the French entry into Lạng Sơn.

The Guangxi Army fell back towards the Chinese border and occupied a strong defensive position at Dong Dang, a small town just in Tonkinese territory.

(The formidable entrenched camps of Ha Hoa and Dong Song are in your hands, with their huge supplies of weapons, ammunition and provisions, which the speed of your attack prevented the enemy from carrying off.

)[15] The second order of the day, issued on 14 February, marked the capture of Lạng Sơn: Vous avez arboré le drapeau français sur Lang-Son.

A Chinese army ten times your numbers has had to recross the frontier in complete rout, leaving in your hands its standards, its arms and its ammunition.

Before his departure he ordered General de Négrier, who would remain at Lạng Sơn with the 2nd Brigade, to press on towards the Chinese border and expel the battered remnants of the Guangxi Army from Tonkinese soil.

Three weeks later the Chinese attacked the Dong Dang garrison, precipitating a series of events that led to a decisive French defeat at the Battle of Bang Bo (24 March 1885).