Wall. On February 23, 1933, the offensive was launched. On February 25, Chaoyang and Kailu were taken. On March 2, the Japanese 4th Cavalry Brigade encountered resistance from the forces of Sun Dianying, and after days of fighting, took Chifeng. On March 4, Japanese cavalry and the 1st Special Tank Company took Chengde the capital of Rehe. Falling back from Rehe, Wan Fulin's 32nd Army retreated to Lengkou Pass, while the 29th Army of General Song Zheyuan also fell back, Zhang Zuoxiang's 37th Division retreated to Xifengkou Pass, General Guan Linzheng's 25th Division to the Gubeikou Pass. On March 4, the 139th Division of the KMT 32nd Army managed to hold Lengkou Pass, and on March 7, the KMT 67th Army withstood attacks by the 16th Brigade of the Japanese 8th Division, at Gubeikou Pass. On March 9, Chiang Kai-shek held discussions with Zhang Xueliang in Baoding about resisting the Japanese invasion. Chiang Kai-shek began to relocate his forces away from his campaign against the Jiangxi Soviet, which would include the forces of Huang Jie, Xu Tingyao and Guan Linzheng. Chiang Kai-shek also called over Fu Zuoyi's 7th Army from Suiyuan. However, his actions were too late and the reinforcements were of insufficient strength to stop the Japanese advance. On March 11, Japanese troops pushed up to the Great Wall itself. On March 12, Zhang Xueliang resigned his post to He Yingqin who, as the new leader of the Northeastern Army, was assigned the duty of securing defensive positions along the Great Wall. Over twenty close assaults were launched, with sword-armed Northwestern Army soldiers repelling them. However, on March 21, the Japanese took Yiyuankou Pass. The KMT 29th Army evacuated from Xifengkou Pass on April 8. On April 11, Japanese troops retook Lengkou Pass after dozens of seesaw fights over the pass defenses and Chinese forces at Jielingkou abandoned that pass. The Chinese army was significantly underarmed in comparison to the Japanese and many units were equipped with predominantly with handguns, hand grenades, and traditional Chinese swords with limited supplies of trench mortars, heavy machine guns, light machine guns and rifles. Beaten back by overwhelming Japanese firepower, on May 20, the Chinese army retreated from their remaining positions on the Great Wall. Although the National Revolutionary Army (NRA) suffered defeat in the end, several individual NRA units like the He Zhuguo platoon managed to hold off the better equipped Japanese