Operation Chahar Operation Chahar , known by the Japanese as チャハル作戦 ( Operation Quhar ) and by the Chinese as the 长城抗战 ( Battle of the Great Wall ) , occurred in August 1937 , following the Battle of Beiping - Tianjin at the beginning of the Second Sino - Japanese War . 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 . 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 Army Group , and Liu Ju - ming , 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 Corps from the Central Army and made Frontline Commander in Chief . The 1st Cavalry Corps was sent to Chahar under the command of Chiao Cheng - shou , facing the Mongolian forces of Teh Wang . Chinese Order of battle . Following the loss of Peiking , Tang Enbo ' s 13th Corps ( 4th and 89th Divisions ) took up positions in depth along the Peiking – Suiyuan Railway at Nankou , and further to the rear at Juyongguan ( Juyong Pass ) . Gao ' s 17th Corps stationed its 84th Division at Chihcheng , Yenching , and Lungkuan , covering the flank of the 13th Corps from Japanese forces in Chahar . The 21st Division was deployed in Huailai , on the railroad to the rear of Tang ' s forces . Zhao Cheng - shou ' s 1st Cavalry Corps , Liu Ru - ming ' s 143rd Division , and two Peace Preservation Brigades began an attack on the Mongol forces in northern Chahar . Battle of Nankou . On August 8 the Japanese 11th Independent Mixed Brigade , commanded by Gen . Shigiyasu Suzuki , began their attack on the left flank of the 13th Corps position at Nankou , but were thwarted after three days by the difficult terrain and the stubborn resistance of the Chinese . A new attack on August 11 , supported by tanks and aircraft , took Nankou Station , after which Gen . Suzuki ' s brigade advanced on Juyong Pass . That same day , Chiang Kai - shek ordered the activation of the 14th Army Group ( 10th , 83rd , and 85th Divisions ) under Gen . Wei Li - huang . Coming by rail from Yingchia - chuang to Yi Hsien , elements of the 14th Army Group were sent on a ten - day march through the plains west of Peiking in a flanking movement in support of Tang Enbo ' s forces . The Chinese 1st Army made attacks on the Japanese forces in Lianghsiang and Chaili to distract them , and sent a detachment to Heilung Pass to cover the advance of 14th Army Group . From the dates on a Japanese map of the battle , these forces did not reach the area until September , when it was too late , and clashed with Japanese forces from September 9 – 17 without achieving its objective . On August 12 , Tang Enbo ' s army counterattacked , surrounding the Japanese and cutting them off from their supplies and communications . On Aug 14th , Seishirō Itagaki ' s 5th Division was sent to the relief of the 11th Independent Mixed Brigade at Juyongguan . On August 16 , Itagaki arrived at Nankou and began an enveloping attack on the right flank of 13th Corps , making a five pronged attack at Huanglaoyuan . The 7th Brigade of 4th Division under Shih Chueh was moved to block this maneuver , and reinforcements of Li Hsien - chou ' s 21st Division and Chu Huai - ping ' s 94th Division were brought up , engaging in days of heavy fighting . On August 17 General Yan Xishan , Director of the Taiyuan Pacification Headquarters , directed the 7th Army , under Fu Zuoyi , to move its 72nd Division and three brigades by rail from Tatung to Huailai to reinforce Gen . Tang Enbo ' s forces . Battle of the Great Wall . Meanwhile in northern Chahar the Chinese 1st Cavalry Corps captured Shangtu , Nanhaochan , Shangyi and Huateh from the puppet Mongolian Army of Prince Teh . Elements of the 143rd Division took Chungli , while its main force reached Changpei . During this Chinese advance the Japanese Chahar Expeditionary Force under Lt . General Hideki Tōjō , composed of the mechanized 1st Independent Mixed Brigade and the 2nd and 15th Mixed Brigades , gathered for a counteroffensive from Changpei to Kalgan . From August 18 – 19 the Chahar Expeditionary Force counterattacked from Changpei , and took Shenweitaiko on the Great Wall and the Hanno Dam . The scattered and poorly equipped Chinese forces were unable to stop the Japanese , who now threatened the Peiking – Suiyuan Railway at Kalgan . On August 20 Gen . Fu Zuoyi ' s 7th Army diverted its 200th and 211th Brigades , which had been moving south by rail to join Gen . Tang Enbo ' s forces , back to defend Kalgan . Fu ' s remaining 72nd Division arrived to reinforce Chenpien , and his 7th Separate Brigade was sent to defend the railhead at Huailai . On August 21 , the Japanese forces broke through at the cities of Hengling and Chenpien . Gen . Tang Enbo ' s forces awaiting reinforcement ; but , having suffered over 50 % casualties , still defended Huailai , Chuyung Pass , and Yenching . Liu Ju - ming ' s 143rd Division fell back to defend Kalgan from the advancing Japanese . On August 23 , as Seishirō Itagaki ' s 5th Division pushed toward Huailai from Chenpien against Ma Yen - shou ' s 7th Separate Brigade , advance elements of the 14th Army Group arrived on the Japanese flank at Chingpaikou , driving off the Japanese outpost there and contacting the Japanese forces advancing to Chenpien and the front beyond . However , they were delayed in crossing the Yungting River , and their attack was delayed until it was too late to stop the Japanese advance . Due to poor communications they also failed to link up with Gen . Tang En - po ' s forces during the battle . After 8 days and 8 nights fighting , Itagaki , on August 24 , linked up with the Kwantung army ' s 2nd Independent Mixed Brigade at Xiahuayuan . Withdrawal . On August 26 , Gen . Tang Enbo ' s forces were ordered to break out toward the Sangchien River while Liu Ju - ming ' s forces were ordered to withdraw to the far side of the Hsiang - yang River . On August 29 the Japanese unit , called the Oui Column by the Chinese and the Ohizumi Detachment ( 大泉支隊 ) by the Japanese , attacked . According to Hsu Long - hsuen this unit moved south from Tushihkou , and on August 30 attacked Yenching via Chihcheng , but was repulsed by the Chinese 17th Corps . A Japanese map of the campaign shows that the unit moved to Guyuan ( 沽源 ) on August 25 and to Xuanhua ( 宣化 ) by September 7 , cutting the railroad in the rear of Tang ' s forces and east of Chinese forces along the Great Wall . According to the Chinese account , after repulsing the Oui Column ' s attack the Chinese 17th Corps withdrew to join the rest of Tang Enbo ' s force on the far side of the Sangchien River . Kalgan fell to the Japanese on September 3 . After Gen . Fu Zuoyi ' s 200th and 211th Brigades failed in a counterattack to recapture Kalgan , Fu ' s forces fell back to the west to defend the railway to Suiyuan at Chaikoupao . This brought and end to Operation Chahar . According to " Time magazine " magazine , on September 4 the Japanese - aligned South Chahar Government was set up at Kalgan . After the fall of Kalgan , Chahar ' s " complete independence " from China was declared by " 100 influential persons " , headed by Prince Teh , a pro - Japanese Mongolian who had long been the head of the " Inner Mongolia for Inner Mongolians " movement . It was Prince Teh , with his Mongolian levies , who helped the Japanese to take Kalgan . Prince Teh was rewarded for his collaboration with the highest position in this new Japanese puppet state , the Mongol United Autonomous Government . Notes