刘永福
The Vietnamese government, unable to confront Rivière with its own ramshackle army, once again enlisted the help of Liu Yongfu, whose well-trained and seasoned Black Flag soldiers would prove a thorn in the side of the French. The Vietnamese also bid for Chinese support. Vietnam had long been a tributary state of China, and China agreed to arm and support the Black Flags, and to covertly oppose French operations in Tonkin.