failed disastrously. After resting his troops on 15 December, Courbet again assaulted the defences of Sơn Tây on the afternoon of 16 December. This time the attack was thoroughly prepared by artillery, and delivered only after the defenders had been worn down. At 5 p.m. a Foreign Legion battalion and a battalion of marine fusiliers captured the western gate of Sơn Tây and fought their way into the town. Liu Yongfu's garrison withdrew to the citadel, and evacuated Sơn Tây under cover of darkness several hours later. Courbet had achieved his objective, but at considerable cost. French casualties at Sơn Tây were 83 dead and 320 wounded. The fighting at Sơn Tây also took a terrible toll of the Black Flags, and in the opinion of some observers broke them once and for all as a serious fighting force. Liu Yongfu felt that he had been deliberately left to bear the brunt of the fighting by his Chinese and Vietnamese allies, and determined never again to expose his troops so openly. In March 1884, the French renewed their offensive under the command of General Charles-Théodore Millot, who took over responsibility for the land campaign from Admiral Courbet after the fall of Sơn Tây. Reinforcements from France and the African colonies had now raised the strength of the Tonkin Expeditionary Corps to over 10,000 men, and Millot organised this force into two brigades. The 1st Brigade was commanded by General Louis Brière de l'Isle, who had earlier made his reputation as governor of Senegal, and the 2nd Brigade was commanded by the charismatic young Foreign Legion general François de Négrier, who had recently quelled a serious Arab rebellion in Algeria. The French target was Bắc Ninh, garrisoned by a strong force of regular Chinese troops of the Guangxi Army. The Bắc Ninh Campaign was a walkover for the French. Morale in the Chinese army was low, and Liu Yongfu was careful to keep his experienced Black Flags out of danger. Millot bypassed Chinese defences to the southwest of Bắc Ninh, and assaulted the city on 12 March from the southeast, with complete success. The Guangxi Army put up a feeble resistance, and the French took the city with ease, capturing large quantities of ammunition and a number of brand new Krupp cannon. The Tientsin Accord and the Treaty of Huế The defeat at Bắc Ninh, coming close on the heels of