The French post at Tuyên Quang was defended for four months against 12,000 troops of the Yunnan Army and the Black Flag Army by two companies of the French Foreign Legion during the Sino-French War (August 1884 to April 1885). The Siege of Tuyên Quang is still remembered as one of the Legion's most celebrated feats of arms, and is commemorated in the first verse of "Le Boudin", its principal marching song.