The Foreign Legion's First Battalion (Lieutenant-Colonel Donnier) sailed to Tonkin in the autumn of 1883, during the period of undeclared hostilities that preceded the Sino–French War (August 1884 to April 1885), and formed part of the attack column that stormed the western gate of Son Tay on 16 December. The Second and Third Infantry Battalions ( chef de bataillon Diguet and Lieutenant-Colonel Schoeffer) were also deployed to Tonkin shortly afterwards, and were present in all the major campaigns of the Sino-French War. Two Foreign Legion companies led the defence at the celebrated Siege of Tuyên Quang (24 November 1884 to 3 March 1885). In January 1885 the Foreign Legion's 4th Battalion ( chef de bataillon Vitalis) was deployed to the French bridgehead at Keelung (Jilong) in Formosa (Taiwan), where it took part in the later battles of the Keelung Campaign . The battalion played an important role in Colonel Jacques Duchesne 's offensive in March 1885 that captured the key Chinese positions of La Table and Fort Bamboo and disengaged Keelung.