Second Zhili–Fengtian War
During the Second Zhili–Fengtian War in 1924, as the Fengtian clique General Zhang Zongchang moved down the Tianjin-Pukou railway toward Jiangsu and eventually Shanghai, Zheng Shiqi declared Shandong's neutrality and forced Zhang's forces into retreat to Cangzhou. But when a government with Duan Qirui was installed as head of state of China, at the beginning of December Duan permitted Fengtian forces to occupy Jiangsu while guaranteeing Zheng's position at Shandong. Zheng then permitted Fengtian troops to pass, and on December 10 he abandoned his neutrality, joining the Fengtian forces.