The Black Flag Army (Chinese: H?iq? J?n; Vietnamese: Qu?n c? ?en) was a splinter remnant of a bandit group recruited largely from soldiers of ethnic Zhuang background, who crossed the border from Guangxi province of China into Upper Tonkin, in the Empire of Annam (Vietnam) in 1865. They became known mainly for their fights against French forces in cooperation with both Vietnamese and Chinese authorities. The Black Flag Army is so named because of the preference of its commander, Liu Yongfu, for using black command flags.