sentences:  In an attempt to eliminate the nationalist threat of Zhangjiakou, the communist decided to first take the nationalist stronghold of Datong in the west by concentrating a total of thirty regiments from nine brigades, and out of the nine brigades, five brigades were to be deployed to assault the city itself, while the remaining four brigades were deployed at regions of Zhuozi Mountain (Zhuo Zi Shan, 卓资山), Earth Castle (Tu Cheng Zi, 土城子), Merchant Capital (Shang Du, 商都) and Cool Castle (Liang Cheng, 凉城) near Jining to stop and ambush the nationalist reinforcement.Defenders