After the capture of Beiping at the end of July 1937, Japanese forces advanced along the Beijing–Baotou Railway to Inner Mongolia. Having anticipated the move, Chiang Kai-shek had appointed the Shanxi warlord Yan Xishan as Pacification Director of Taiyuan. Theoretically Yan had authority over all the Chinese military forces in his theatre of operations, including Lin Biao's 115th Division of the Communist 8th Route Army, Liu Ruming's ex-Kuomintang troops and various Central Army contingents responsible to Chiang Kai-shek. In reality these forces operated independently from Yan's provincial army. Japanese forces, mainly the 5th Division and 11th Independent Mixed Brigade, moved out from Beiping and advanced on Huailai County in Chahar. A Japanese column advanced quickly into Shanxi, making use of the railway which the Chinese did not attempt to destroy. The Chinese abandoned Datong on September 13, falling back to a line from Yanmen Pass onthe Great Wall east to the mountain pass of Pingxingguan. Yan Xishan's troops became more demoralised as the Japanese exerted their air supremacy. The main body of the Japanese 5th Division, under the command of Itagaki Seishiro, advanced from Huaili to invade northeastern Shanxi. Although it had a motorised transport column, its rate of advance was limited by the poor roads. By the time they reached the Shanxi border, Lin Biao's 115th Division, after a forced march from Shaanxi, was in place at Pingxingguan on September 24 to ambush the Japanese army.
Battle
The pass of Pingxingguan was a narrow defile worn through the loess, with no exit for several kilometres except the road itself. Lin's division were able to ambush two columns of mainly transportation and supply units and virtually annihilate the trapped Japanese forces. On September 25, the 21st brigade of the Japanese 5th Division stationed at Lingqiu received a request from the 21st Regiment that they urgently needed supplies due to falling temperature. The supply troops of the 21st Regiment set out with 70 horse-drawn vehicles with 50 horses, filled with clothes, food, ammunition and proceeded westwards towards Pingxingguan. Around 10:00, the supply column passed into a defile with the two sides rising up more than 10 meters; they were heading towards Caijiayu about 3 km away. At the same time, a motorized column of Japanese supply troops in about 80 trucks left Guangou and headed east. Both of these non-combat formations entered into the ambush set by the 115th division after 10 a.m. on the 25th and were largely wiped out. A relief force consisting of the 3rd Battalion of the 21st Regiment was rebuffed by Chinese troops and suffered almost 100 casualties. Lin Biao's troops eventually withdrew from the battlefield, allowing the Japanese to finally reach the site of the ambush on September 28. Japanese casualties in the battle have been estimated at 400 to 500 and the Chinese at about 400. The Chinese forces destroyed about 70 trucks and an equal number of horse-drawn carts and captured 100 rifles, 10 light machine guns, 1 gun, 2000 shells as well as some clothing and food.
Evaluation
The Kuomintang official history of the Second Sino-Japanese War deals with it in a sentence, without any credit to the communists. Communist accounts, on the other hand, describe Pingxingguan as a typical example of Redguerrilla tactics, inspired by Mao Zedong's conceptualization of People's war. Japanese losses were greatly exaggerated for propaganda purposes. However, like the victory at the Battle of Taierzhuang, Pingxingguan was explained by Japan as Japanese officers succumbing to what they came to call "victory disease". After a series of easy victories against their opponents, they failed to take elementary precautions. Japanese commanders seldom repeated the operational blunders that had led to Pingxingguan. Nonetheless, the battle gave the Chinese a major boost in morale and credence to the Communists in the eyes of the people. The battle was constantly cited by CPC leaders as an example of their commitment to battling the Japanese occupation, even though Mao had opposed the battle, according to an account written by Lin Biao in Russia and Lin had undertaken it on his own authority.