Retreat From Lang Son - Background

Background

By the middle of March 1885 the military situation in Tonkin had reached a temporary stalemate. In February 1885, in the Lang Son Campaign, the French had captured Lang Son and driven China's Guangxi Army out of Tonkin. In the second half of February General Louis Brière de l'Isle, the general-in-chief of the Tonkin Expeditionary Corps, returned to Hanoi with Lieutenant-Colonel Laurent Giovaninelli's 1st Brigade to relieve the Siege of Tuyen Quang, leaving General François de Négrier at Lang Son with the 2nd Brigade.

Giovanninelli's 1st Brigade faced Tang Jingsong's Yunnan Army around Hung Hoa and Tuyen Quang, while de Négrier's 2nd Brigade at Lang Son faced Pan Dingxin's Guangxi Army. Neither Chinese army had any realistic prospect of launching an offensive for several weeks, while the two French brigades that had jointly captured Lang Son in February were not strong enough to inflict a decisive defeat on either Chinese army separately. Meanwhile the French government was pressuring Brière de l'Isle to send the 2nd Brigade across the border into Guangxi province, in the hope that a threat to Chinese territory would force China to sue for peace. Brière de l'Isle and de Négrier examined the possibility of a campaign to capture the major Chinese military depot at Longzhou, 60 kilometres beyond the border, but on 17 March Brière de l'Isle advised the army ministry in Paris that such an operation was beyond his strength. Substantial French reinforcements reached Tonkin in the middle of March, giving Brière de l'Isle a brief opportunity to break the stalemate. He moved the bulk of the reinforcements to Hung Hoa to reinforce the 1st Brigade, intending to attack the Yunnan Army and drive it back beyond Yen Bay. While he and Giovanninelli drew up plans for a western offensive, he ordered de Négrier to hold his positions at Lang Son.

On 23 and 24 March the 2nd Brigade, only 1,500 men strong, fought a fierce action with over 25,000 troops of the Guangxi Army entrenched near Zhennanguan on the Chinese border. The Battle of Bang Bo (named by the French from the Vietnamese pronunciation of Hengpo, a village in the centre of the Chinese position where the fighting was fiercest), is normally known as the Battle of Zhennan Pass in China. The French took a number of outworks on 23 March, but failed to take the main Chinese positions on 24 March and were fiercely counterattacked in their turn. Although the French made a fighting withdrawal and prevented the Chinese from piercing their line, casualties in the 2nd Brigade were relatively heavy (70 dead and 188 wounded) and there were ominous scenes of disorder as the defeated French regrouped after the battle. As the brigade's morale was precarious and ammunition was running short, de Négrier decided to fall back to Lang Son.