Short answers, pulled from the story.
The Battle of Pingxingguan occurred on the 25th of September 1937. Chinese forces under Lin Biao and Nie Rongzhen ambushed Japanese military transport trucks in a narrow defile near Shangzai Town that morning.
Lin Biao and Nie Rongzhen led the 115th Division of the Eighth Route Army during the battle. They coordinated the ambush strategy while Yan Xishan held nominal authority over all Chinese military forces in northern Shanxi.
Chinese forces wiped out a battalion of Japanese troops and destroyed more than 80 trucks along with 200 carts at Caijiayu and Xiaozhai Village. The victory significantly boosted Chinese morale and enhanced Communist Party credibility among the populace.
The conflict yielded in excess of 1,000 Japanese losses including annihilation of over 100 vehicles and seizure of one Type 92 infantry cannon. Professor Jiang Keshi believed 6,000 Eighth Route Army soldiers killed or wounded 240 Japanese soldiers on September 25.
The Pingxingguan battlefield site encompassing Laoyemiao was classified in 1961 as one of the inaugural Major Historical and Cultural Sites Protected at National Level in China. It emerged as one of the earliest acknowledged heritage sites of the Anti-Japanese War.