The Garnier Expedition was a French expedition in Tonkin between November 1873 and January 1874. Lieutenant Francis Garnier, who had been sent by France on the demand of Vietnamese Imperial authorities to bring back Jean Dupuis, an unruly French trader who was causing trouble in Hanoi, instead decided to side with Dupuis and captured the city of Hanoi, the capital of the Tonkin region.
Following the capture of the city, Garnier and his small force launched themselves in a lightning military campaign that resulted in the conquest of most of the Tonkin region within three weeks. Garnier was eventually killed in action while repulsing an attack on Hanoi on 21 December, but his men nonetheless remained in control of the region.
However, the campaign had not been planned or even allowed by the French government and a treaty was signed in 1874, which gave back all the conquered cities to Vietnam in exchange for a very favourable trade agreement and the installation of a French resident in Hanoi, as well the official recognition of all French possessions in Cochinchina.
In 1858, France and Spain launched a punitive expedition against the Empire of Đại Nam as a response to the persecution of Christian missionaries and converts. Hostilities ended four years later with the Treaty of Saigon, but the French decided to retain the provinces they had conquered during the war, thus giving birth to the French colony of Cochinchina. In 1867 Admiral Pierre de la Grandière forced the Vietnamese to cede the provinces of Châu Đốc, Hà Tiên and Vĩnh Long to French Cochinchina. Though the French de facto took control of these provinces, the Vietnamese Emperor Tự Đức refused to officially recognize the validity of this cession.
In 1873, French explorer and trader Jean Dupuis traveled up the Red River to sell European weaponry to the governor of Yunnan. Eventually, Dupuis also decided to start carrying salt up the river, something which was strictly prohibited by Vietnamese authorities. A lengthy dispute ensued, and Dupuis eventually occupied a district of Hanoi with his 90 Chinese mercenaries. Unwilling to attempt forcefully removing these very well armed men on their own, the Vietnamese authorities issued a complaint to French admiral Marie Jules Dupré, who was serving as Governor of French Cochinchina at the time. Hoping that he would be able to obtain the official recognition of all French possessions in Cochinchina by the Vietnamese Empire if he accepted to help them, Admiral Duprès sent an expedition under Lieutenant Francis Garnier to Hanoi to solve the dispute and convince Dupuis to leave.
A first group of 83 men, consisting in 51 sailors from the ships D'Estrée and Fleurus, a platoon of 30 marines of the 4th Marine Infantry Regiment and two officers traveled with Lieutenant Garnier on the corvette D'Estrée which departed from Saigon on 11 October.
The second half of the expeditionary force departed two weeks later and consisted in 60 sailors of the companie de débarquement of the corvette Decrès and four officers of that same ship who were brought to Tonkin by the Decrès, and the 28 sailors and one officer who formed the crew of the gunboat Espingole and traveled on the gunboat.
Besides Lieutenant Garnier, the expeditionary force comprised seven officers: Ensign Charles Esmez (aged 26), Ensign Henri Bain de la Coquerie (aged 28), Ensign Adrien Balny d'Avricourt (aged 24), Aspirant Marc Hautefeuille (aged 21), Aspirant Édouard Perrin (aged 21), Aspirant Georges Bouxin (aged 20), and Second-Lieutenant Edgard de Trentinian (aged 22) who commanded the platoon of marines.
Although technically not an officer, the military medic of the Espingole, Jules Harmand, was treated as a de facto officer by Balny d'Avricourt and Trentinian while they were away from the main force, as he was a well-educated man older than both of them (28 years old).
On the early morning of 11 October 1873, the D'Estrée left Saigon, with on its board Lieutenant Francis Garnier, commander-in-chief of the expedition, Ensign Charles Esmez, second-in-command, and the first half of the expeditionary force. The unmanned gunboat Arc was being towed by the D'Estrée.
On 14 October, while the D'Estrée was off the coast near Da Nang, a violent storm broke the tow ropes of the Arc and the unmanned gunboat went adrift for a while before capsizing and sinking. From 15 to 20 October, the D'Estrée made a halt in Da Nang, where Garnier met some Vietnamese officials from Imperial court of Huế, and also sent a telegram to Saigon in order to ask the admiralty to send him the gunboat Scorpion.
The D'Estrée arrived to the Tonkin on 23 October. The corvette remained anchored in the bay of Haiphong while Garnier and his men traveled to Hanoi upriver on local junks. On 5 November, the French party finally arrived to Hanoi. However, the welcome of the local authorities was rather cold for Garnier's liking. Neither the Governor of Hanoi, Marshal Nguyễn Tri Phương, nor any of his mandarins came to meet them.
Dupuis, however, had warmly welcomed the French. After discussing with Dupuis, Garnier became convinced that the anti-French sentiment that Nguyễn Tri Phương openly harbored ever since his defeat against French forces 12 years earlier had led him to mistreat Dupuis and that the griefs of the trader were thus justified. Garnier made some attempts to negotiate with the local authorities, but as they all remained fruitless, he began considering the idea of some military action. However, his forces were quite small, and he was still without news of the second half of his escort force.
The Espingole finally arrived to Hanoi alongside the Scorpion on 12 November. With two gunboats and the 180 men of his expeditionary force finally reunited, Garnier took the decision to capture the city. Garnier wrote a letter to Admiral Dupré to justify his attack on Hanoi and sent the D'Estrée back to Saigon to carry the letter.
At daybreak on 20 November, the French launched their assault. A 30-man strong French detachment under Ensign Bain went with one cannon to attack the South-Western gate as a distraction. Not long after, a group of 27 marines and 48 sailors with 4 cannons under Lieutenant Garnier, Second-lieutenant Trentinian and Ensign Esmez attacked the South-Eastern gate. As soon as the first sounds of French cannons were heard, the two gunboats Scorpion and Espingole, under the leadership of Ensign Balny d'Avricourt, started shelling the Northern and the Western gates of the citadel.
The detachment under Bain swiftly captured the redan of the South-Western gate and eventually took over the gate as well after having blown up the door. Having received no order to enter however, they remained at the entrance. At the South-Eastern gate, Garnier and his men had easily taken the redan but had experienced some difficulties to blow up the door. Garnier entered first through a breach alongside Trentinian and two marines, but they had to wait until the door was blown up for the rest of the troops to get in. Once the French stormed inside, the low Vietnamese morale completely collapsed and all the defenders ran away toward the Northern gate to escape the citadel.
Once inside the fortress, Garnier's attention became focused on trying to prevent the important officials from escaping alongside the bulk of their soldiers. He immediately sent Aspirant Hautefeuille with some men to secure the Eastern entrance and then went to meet Bain at the South-Western entrance to order him and his men to go and watch over the Western gate.
Dupuis and 30 of his mercenaries had been tasked with monitoring the Eastern gate from outside, but they ended up taking the redan and eventually stormed inside the citadel. While inside, they met with the detachment led by Hautefeuille at the corner of a street and a Chinese mercenary was killed during a brief fusillade that resulted from the French having mistaken them for Vietnamese soldiers.