During the summer and autumn of 1884 it was garrisoned by two companies of the 1st Battalion, 1st Foreign Legion Regiment (Captains Chmitelin and Broussier), under the command of chef de bataillon Frauger.

The outbreak of the Sino-French War on 23 August 1884 exposed the post to attack by Tang Jingsong's Yunnan Army and Liu Yongfu’s Black Flags.

[3] In November 1884 General Louis Brière de l'Isle, the commander of the Tonkin Expeditionary Corps, took steps to resupply and reinforce Hung Hoa, Thai Nguyen and Tuyên Quang.

On 19 November a column making for Tuyên Quang under the command of Lieutenant-Colonel Jacques Duchesne was ambushed in the Yu Oc gorge by the Black Flags but was able to fight its way through to the beleaguered post.

Frauger and his men were relieved, and replaced by a fresh garrison of 400 legionnaires and 160 Tonkinese riflemen under the command of chef de bataillon Marc-Edmond Dominé of the 2nd African Light Infantry Battalion.

The garrison was supported by the Farcy gunboat Mitrailleuse (enseigne de vaisseau Senes), at anchor in the Clear River close to the French post.

Lying on the western bank of the Clear River next to the Tonkinese village of Tuyên Quang, it consisted of a square masonry citadel, each of whose walls was 300 yards long.

[8] In November 1884 the Yunnan Army gradually advanced down the Red River from Lao Cai towards Tuyên Quang, building a chain of entrenched camps at Pho En, Man Lanh, Ao Loc, Van Kieng and Son Long.

In December the Chinese built three enormous fortified camps as bases for the siege of Tuyên Quang, at Thanh Quan, Ca Lanh and Phu An Binh.

The besiegers gradually drew their lines closely around the French post at Tuyên Quang, occupying the villages of Phu An Binh, Dong Yen and Ya Ho to the west of the fortress and Yla, Ung Di and Truong Mu to the northwest.

From then on, attacks were made on the French positions almost daily and the defenders were subjected to an almost continual barrage of cannon, mortar and rifle fire from all sides.

Dominé occasionally brought his own artillery into play, and the gunboat Mitrailleuse harassed the Chinese positions on the Clear River with Hotchkiss fire.

If they could mine the walls and collapse sections of the defence perimeter, they could bring their superior numbers to bear by assaulting the French through open breaches.

On 11 February a pick-axe blow severed the membrane which separated a French from a Chinese miner, and an underground revolver fight took place.

Captain Moulinay rushed to the threatened point with his company, halted an enemy attack, and threw the assailants back to their forward trenches.

The body of a French legionnaire was thrown onto the enemy parapets by the force of the explosion, and on the following night Corporal Beulin of the Legion took a party of three soldiers to go out into no-man's-land and recover it.

Dominé had a redoubt built in the southeast corner of the fortress, where a final stand could be made if the Chinese carried the perimeter walls by assault.

But although the garrison had beaten off six attempts to storm its positions, it had lost over a third of its strength (50 dead and 224 wounded) sustaining a heroic defence against overwhelming odds.

General Brière de l’Isle personally led Lieutenant-Colonel Laurent Giovanninelli's 1st Brigade back to Hanoi, and then upriver to the relief of Tuyên Quang.

The Yunnan Army and the Black Flags raised the siege and drew off to the west, and the relieving force entered the beleaguered post on the afternoon of 3 March.

Knowing that the relief column was close and that it would be their last chance to capture the post, the Chinese attacked with fanatical courage but once again failed to force the breach.

On 2 March the men of the Tuyên Quang garrison listened anxiously to the sounds of rifle and cannon fire from the Yu Oc gorge, where the 1st Brigade was fighting to break through to the beleaguered post.

Several years later he made what amends he could by publishing a moving poem to the fellowship of the French Foreign Legion, A mes hommes qui sont morts.

The dead included the engineering sergeant Jules Bobillot, whose energetic countermeasures had delayed the progress of the Chinese siege works.

"[15] (Under the orders of your gallant commander chef de bataillon Dominé, you 600 men held off an entire army for 36 days, in a small outpost overlooked from all sides.

One man in every three of you and nearly all your officers were scorched by mines or struck by Chinese bullets and shells; but the bodies of the enemy still choke the three breaches vainly made in the fortress's defences.

Their troops were excellent, and although they were unable to capture the fortress, defended as it was by a handful of heroes and relieved in the very nick of time by Giovanninelli’s brigade, this siege was nonetheless a glorious feat of arms for the Celestials and showed that when necessary they could rise to the occasion.