Complex sentence: In 1921 Chen pushed into Guangxi, starting the Second Ao-Gui war, forcing Lu Rongting to step down in July 1921 and by August, Chen had occupied Nanning and the rest of Guangxi.
Split into simpler sentences: In 1921 Chen pushed into Guangxi, starting the Second Ao-Gui war, forcing Lu Rongting to step down in July 1921. By August, Chen had occupied Nanning and the rest of Guangxi.