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.

On 30 July 1883 Admiral Courbet, General Bouët and 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 Hoang was still in arms against the French at Nam Định.

[Note 3] Bichot's column, whose right flank lay on the Red River, was supported by six French gunboats (Pluvier, Léopard, Fanfare, Éclair, Mousqueton and Trombe) from the Tonkin Flotilla, under the command of capitaine de vaisseau Morel-Beaulieu.

The first, outpost, line ran from the village of Cau Giay near Paper Bridge, the scene of Rivière's defeat and death on 19 May, to the Pagoda of the Four Columns (Quatre Colonnes[6]) on the Red River.

Their retreat nearly turned into a rout, as the Vietnamese coolies with the column streamed to the rear in panic, blocking the dyke paths along which fresh supplies of ammunition were being brought forward.

However, Chevallier's marine infantry battalion, firing from sheltered positions in the village of Vong, successfully covered the French withdrawal, inflicting heavy casualties on Black Flag units that left their defences and ventured out into the open.

The battle had been fought in pouring rain, and during the night of 15 August the Red River burst its banks and began to flood the plains between Hanoi and Phu Hoai.

[7] Although the French severely mauled the Black Flag Army during the battle and suffered relatively low casualties in return, their failure to win a clear victory against Liu Yongfu was widely noted.

Although the atrocious weather was the most important reason for the failure of Bouët's attack, poor French command decisions and the extremely stubborn defence put up by the Black Flags were also contributory factors.