Operation Chahar

Operation Chahar (Japanese: チャハル作戦, romanized: Chaharu Sakusen), known in Chinese as the Nankou Campaign (Chinese: 南口戰役; pinyin: Nankou Zhanyi), occurred in August 1937, following the Battle of Beiping-Tianjin at the beginning of Second Sino-Japanese War.

This was the second attack by the Kwantung Army and the Inner Mongolian Army of Prince Demchugdongrub on Inner Mongolia after the failure of the Suiyuan Campaign. 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 Beiping Railway Garrison Force, later the 1st Army under General Kiyoshi Katsuki, was also involved.

Japanese Order of battle

The Chinese forces opposing this invasion of Suiyuan were the Suiyuan Pacification Headquarters under the command of General Yan Xishan. Fu Zuoyi, the governor of Suiyuan, was made commander of the 7th Group Army, and Liu Ruming, governor of Chahar, was made its deputy commander, defending Chahar with the 143rd Division and two Brigades. General Tang Enbo was sent by Chiang Kai-shek with the 13th and 17th Armies from the Central Army and made Frontline Commander in Chief. The 1st Cavalry Army was sent to Chahar under the command of Zhao Chengshou, facing the Mongolian forces of Demchugdongrub.

Chinese Order of battle

Following the loss of Beiping, Tang Enbo's 13th Army (4th and 89th Divisions) took up positions in depth along the Peking–Suiyuan Railway at Nankou, and further to the rear at Juyongguan (Juyong Pass). Gao's 17th Army stationed its 84th Division at Chicheng (赤诚), Yanqing (延庆), and Longguan, covering the flank of the 13th Army from Japanese forces in Chahar.