흑기군
In 1863, Wong started a martial arts school in Shuijiao () in Saikwan (Xiguan), which is a present day location of Liwan District, Guangzhou City. His students were mainly metal labourers and street vendors. In 1886, Wong opened his family's medical clinic, Po Chi Lam (寶芝林; Baozhilin), in Ren'an (), which is a present day part of Xiaobei Road, Yuexiu District, Guangzhou City. In legend, around the 1860s or 1870s, Wong was recruited by Liu Yongfu, the commander of the Black Flag Army, to be the medical officer and martial arts instructor for the regular soldiers and the local militia in Guangzhou. He also followed the Black Flag Army to fight the Imperial Japanese Army during the Japanese invasion of Taiwan in 1895.