sentences:  Li was then appointed commander of the Fourth Army Group, composed of the Guangxi Army and other provincial forces amounting to 16 corps and six independent divisions.In April 1928, Li Zongren, with Bai Chongxi, who was credited with many victories over the northern warlords, led the Fourth Army group to advance on Beijing, capturing Handan, Baoding, and Shijiazhuang, by June 1.Zhang Zuolin withdrew from Beijing on June 3, and Li's army seized Beijing Bai commanded the forward units which first entered Beijing and Tianjin.