war strength of six battalions. Sino-French War In December 1883, the 1st Battalion of the Foreign Legion participated in the capture of Sơn Tây. In May 1884 after a short French offensive campaign, France and China agreed that Chinese forces would be withdrawn from Tonkin. However, in June 1884, hostilities between France and China resumed at Lạng Sơn after a French force attempted to dislodge a Chinese garrison which had not withdrawn from the Tonkin region. Following the Chinese renewal of hostilities, French Prime Minister Jules Ferry began preparations for an invasion. In 1884 two battalions of the Foreign Legion were attached to the 4th Marching Regiment of the 2nd Brigade of the Tonkin Expeditionary Corps during the Bắc Ninh Campaign. In November 1884, a column of 700 legionnaires under command of Lieutenant-colonel Jacques Duchesne, commanding officer of the 4th Marching Regiment, proceeded up the Lô River valley. The column assaulted a Chinese fortified position along a ridge south of Tuyên Quang. Then when the column reached Tuyên Quang and a garrison was established in the town; the garrison was composed primarily of Legion forces. The column departed Tuyên Quang on November 23, 1884 and the Tuyên Quang garrison was subsequently surrounded by Black Flag forces, marking the commencement of the Siege of Tuyên Quang. French military operations elsewhere in Indochina had been restricted by order of the French Minister of War Jean-Baptiste Campenon to the confines of the Red River Delta, however on January 3, 1885 Jules Louis Lewal succeeded Campenon as Minister of War. This permitted General Louis Brière de l'Isle to organize the Lạng Sơn expeditionary column to clear resistance along the Mandarin Road, a route from Hanoi through Lạng Sơn up to the Chinese border. Elements of the Foreign Legion were part of the Lạng Sơn Expeditionary column, again as part of the 4th Marching Regiment. This relief column set north on campaign on February 3, 1884 and began encountering resistance by February 5. The French column assaulted Chinese defensive fortifications along the Mandarin Road, however this strategy proved imprudent as these fortifications proved costly to assault directly. During these assaults, one company of the Foreign Legion lost a third of its strength including its entire officer cadre and subsequent command of the company fell to its sergeant major. At the Battle of Đồng Đăng, a Foreign Legion battalion lead the vanguard of the French advance.