These reinforcements were organised into a Tonkin Expeditionary Corps, which was placed under the command of général de brigade Alexandre-Eugène Bouët (1833–87), the highest-ranking marine infantry officer available in the French colony of Cochinchina.

The French had only small garrisons in Hanoi, Haiphong and Nam Định, isolated posts at Hon Gai and at Qui Nhơn in Annam, and little immediate prospect of taking the offensive against Liu Yongfu's Black Flags and Prince Hoàng Kế Viêm's Vietnamese.

[8] The arrival of Admiral Amédée Courbet in Ha Long Bay in July 1883 with substantial naval reinforcements further strengthened the French position in Tonkin.

On 30 July 1883 Admiral Courbet, General Bouët and François-Jules Harmand, the recently appointed French civil commissioner-general for Tonkin, held a council of war at Haiphong.

They also noted that the Court of Huế was covertly aiding and abetting Liu Yongfu's Black Flag Army, and that Prince Hoàng was still in arms against the French at Nam Định.

France was granted the privilege of stationing a resident-general at Huế, who would work to the civil commissioner-general in Tonkin and could require a personal audience with the Vietnamese emperor.

[12] More encouragingly for the French, a column of marine infantry and Cochinchinese riflemen under the command of Lieutenant-Colonel Brionval stormed the Vietnamese defences of Hải Dương on 13 August.

Although the Vietnamese governor of Ninh Bình had made no attempt to hinder the passage of the expedition launched by Henri Rivière in March 1883 to capture Nam Định, he was known to be hostile towards the French.

Admiral Amédée Courbet, who had replaced Bouët in command of the Tonkin Expeditionary Corps two months earlier, assembled a column of 9,000 men and marched on Sơn Tây for a showdown with Liu Yongfu's Black Flag Army.

The French government appreciated that an attack on Sơn Tây would probably result in an undeclared war with China, but calculated that a quick victory in Tonkin would force the Chinese to accept a fait accompli.

Although the Chinese and Vietnamese contingents at Sơn Tây played little part in the defence, Liu Yongfu's Black Flags fought ferociously to hold the city.

On 11 April 1884 Millot captured Hưng Hóa and Dong Yan, flanking the Black Flag Army and its Vietnamese allies out of a formidable defensive position without losing a man.

Millot despatched Lieutenant-Colonel Letellier with two Turco battalions and supporting cavalry to harry Liu Yongfu's retreat, and sent General Brière de l'Isle with the rest of the 1st Brigade in pursuit of Prince Hoang.

In early May Brière de l'Isle cornered Prince Hoang in Phu Ngo, several kilometres to the northwest of Ninh Bình, but the French government forbade him to attack the Vietnamese defences, having just received news that China was ready to treat with France over the future of Tonkin.

[24] In theory, the Tientsin Accord should have resolved the confrontation between France and China in Tonkin, but a clash between French and Chinese troops at Bac Le on 23 June 1884 plunged both countries into a fresh crisis.

In September 1884 General Millot resigned as general-in-chief of the Tonkin Expeditionary Corps and was replaced by his senior brigade commander, Louis Brière de l'Isle.

One of his first acts as general-in-chief, in September 1884, was to seal off Tonkin from Annam by ejecting Vietnamese bandit concentrations from the border towns of My Luong, Ke Son and Phu Ngo and establishing French posts there.

During the second fortnight of February Colonel Laurent Giovanninelli's 1st Brigade marched down the Mandarin Road to Hanoi and was then ferried up the Red and Clear Rivers to Phu Doan aboard a flotilla of gunboats.

[30] In March 1885 the French established posts at Cau Son and Thanh Moy, previously occupied by the Guangxi Army, and began to widen the Mandarin Road so that it could be used by wagon trains to supply de Négrier's 2nd Brigade at Lạng Sơn.

[31] In the west, Giovanninelli's victory at Hòa Mộc on 2 March allowed the French to consider an offensive from their main base at Hưng Hóa against the Yunnan and Black Flag Armies.

Brière de l'Isle drew up plans for an advance up the Red River by Giovanninelli's brigade against the Yunnan Army's positions around Thanh Quan, but simultaneous reverses on both the eastern and western fronts on 24 March (the Battle of Bang Bo (Zhennan Pass) and the Battle of Phu Lam Tao) and the subsequent Retreat from Lạng Sơn on 28 March threw out his plans for an early penetration of the upper course of the Red River.

In May and June 1885 thousands of fresh French troops poured into Tonkin, swamping the veterans of the two brigades that had fought the Sino-French War, and the expeditionary corps was reorganised into two two-brigade divisions.

It was also memorable for a cholera epidemic which swept through the expeditionary corps in the summer and autumn of 1885, exacerbated by de Courcy's neglect of quarantine precautions, in which more French soldiers died than in the entire nine months of the Sino-French War.

The Chinese armies that had fought the Sino-French War dutifully withdrew from Tonkin in May and June 1885, but their ranks were by then full of Vietnamese volunteers or conscripts, and these men, unpaid for months, were simply disbanded on Tonkinese soil and left to fend for themselves.

[35] No attempt was made by de Courcy to move forward to reoccupy Lạng Sơn, evacuated by the Chinese in May, nor to secure the forts built by the Yunnan Army along the Red River to protect its supply line during the Siege of Tuyên Quang.

In July 1885 a mixed column of Algerian and Tonkinese riflemen under the command of Colonel Mourlan drove a band of insurgents from the Tam Dao massif and established a French post at Lien Son.

The Tonkin expeditionary corps undertook a large-scale campaign in October 1885 to capture the Yunnan Army's old base at Thanh May, which had been occupied by Vietnamese insurgents some months earlier.

Significantly, General François de Négrier was forced to make a major sweep of the Bai Sai region near Hanoi in December 1885, an operation in which hundreds of French troops died of cholera and other diseases.

[44] The veterans were further offended by the arrangements made for the Bastille Day parade of 14 July 1886, an imposing annual march through the streets of Paris by the men of France's armed and disciplined services.

Instead, the man who rode at the head of the march past was the controversial and ambitious new army minister General Georges Boulanger, who only three years later would be suspected of plotting a coup against the Third Republic.