 On September 18 the opposing armies met, with battle drastically intensifying after September 28.Fengtian assaults on Shanhaiguan were thrown back as Zhili forces took up defensive positions and enjoyed geographical advantages.Meanwhile, as agreed previously, Dr. Sun Yat-sen personally led his army north to prevent Sun Chuanfang from reinforcing his Zhili comrades in the north, but a rebellion by the Canton Merchant Corps and Chen Jiongming loyalists broke out in Guangzhou.