关东军
This was the second attack by the Kwantung Army and the Inner Mongolian Army of Prince Teh Wang on Inner Mongolia after the failure of the Suiyuan Campaign (1936). The Chahar Expeditionary Force was under the direct command of General Hideki Tōjō, the chief of staff of the Kwantung Army. A second force from the Peiping Railway Garrison Force, later the 1st Army under General Kiyoshi Katsuki, was also involved.