On 31 December 1884 the Chinese launched an initial attack, which was repelled with losses.
 They attacked again on 10 January and 26 January 1885, but with no more success.
 But at the same time they had diverted more than 1,000 men to work on digging saps in order to approach the walls of the fortress from the southwest and the north simultaneously.
 On 27 January their trenches were less than 1,000 metres from the French walls, and they began to sap towards the blockhouse.
As its communications with the citadel were threatened, the blockhouse had to be abandoned on 30 January.
The guns which Dominé had at his disposal were of too low a calibre to do any serious damage to the enemy trenches.

The Chinese converted the abandoned French blockhouse into a fortified position for a battery of four cannon and drew their encirclement of the French post closer.
 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.
 The French did what they could to respond.
 Dominé posted 25 crack Legion marksmen on the citadel's watchtowers with orders to fire at Chinese soldiers working as labourers on the approach saps in order to disrupt the progress of the Chinese siege works.
 The Legion snipers normally took nine or ten victims a day, and by the end of the siege estimated that they had accounted for over 700 enemy soldiers.
Dominé occasionally brought his own artillery into play, and the gunboat Mitrailleuse harassed the Chinese positions on the Clear River with Hotchkiss fire.
 The Chinese responded by deploying their own snipers on hill positions around the French post.
 They rarely hit their targets, but the weight of plunging fire they were able to bring to bear severely restricted movement inside the fortress.

Having successfully forced the French from the outlying blockhouse by siege tactics, the Chinese sapped relentlessly towards the French perimeter wall.
 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.
 The Chinese intentions were obvious, and the French engineering sergeant Jules Bobillot did his best to frustrate them.
 Both the French and the Chinese feverishly dug galleries and counter-galleries.
 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.
 The French tried vainly to flood the Chinese saps, which were lower than theirs.
 On the evening of 12 February the first Chinese mine was exploded beneath the perimeter wall, but its effect was weakened by the counter-galleries and a subsequent Chinese assault was repelled with heavy losses.

Another mine, which exploded on 13 February, made a 15-metre breach in the southwest wall of the citadel.
 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.

On 17 February the Chinese brought up fresh guns, and the bombardment (cannon and mortar fire by night, rifle fire by day) now continued without a pause.
 Most of the buildings became uninhabitable, and the French had to abandon them and live in foxholes.
 Supplies of cigarettes had by now run out, trying the defenders' nerves still further.
 Sleep became increasingly difficult, and in daytime most French soldiers not on duty at the perimeter wall were busy digging additional inner defences.
 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.

At 7 a.m. on 22 February the Chinese delivered their fourth assault.
 After exploding a mine and making a feint attack to draw t
On 31 December 1884 the Chinese launched an initial attack, which was repelled with losses.  They attacked again on 10 January and 26 January 1885, but with no more success.  But at the same time they had diverted more than 1,000 men to work on digging saps in order to approach the walls of the fortress from the southwest and the north simultaneously.  On 27 January their trenches were less than 1,000 metres from the French walls, and they began to sap towards the blockhouse. As its communications with the citadel were threatened, the blockhouse had to be abandoned on 30 January. The guns which Dominé had at his disposal were of too low a calibre to do any serious damage to the enemy trenches.
The Chinese converted the abandoned French blockhouse into a fortified position for a battery of four cannon and drew their encirclement of the French post closer.  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.  The French did what they could to respond.  Dominé posted 25 crack Legion marksmen on the citadel's watchtowers with orders to fire at Chinese soldiers working as labourers on the approach saps in order to disrupt the progress of the Chinese siege works.  The Legion snipers normally took nine or ten victims a day, and by the end of the siege estimated that they had accounted for over 700 enemy soldiers. Dominé occasionally brought his own artillery into play, and the gunboat Mitrailleuse harassed the Chinese positions on the Clear River with Hotchkiss fire.  The Chinese responded by deploying their own snipers on hill positions around the French post.  They rarely hit their targets, but the weight of plunging fire they were able to bring to bear severely restricted movement inside the fortress.
Having successfully forced the French from the outlying blockhouse by siege tactics, the Chinese sapped relentlessly towards the French perimeter wall.  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.  The Chinese intentions were obvious, and the French engineering sergeant Jules Bobillot did his best to frustrate them.  Both the French and the Chinese feverishly dug galleries and counter-galleries.  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.  The French tried vainly to flood the Chinese saps, which were lower than theirs.  On the evening of 12 February the first Chinese mine was exploded beneath the perimeter wall, but its effect was weakened by the counter-galleries and a subsequent Chinese assault was repelled with heavy losses.
Another mine, which exploded on 13 February, made a 15-metre breach in the southwest wall of the citadel.  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.
On 17 February the Chinese brought up fresh guns, and the bombardment (cannon and mortar fire by night, rifle fire by day) now continued without a pause.  Most of the buildings became uninhabitable, and the French had to abandon them and live in foxholes.  Supplies of cigarettes had by now run out, trying the defenders' nerves still further.  Sleep became increasingly difficult, and in daytime most French soldiers not on duty at the perimeter wall were busy digging additional inner defences.  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.
At 7 a.m. on 22 February the Chinese delivered their fourth assault.  After exploding a mine and making a feint attack to draw t
Siege of Tuyên Quang