sentences:  On August 20, 1949, the communist I Corps took Kangle, threatening Linxia, while the communist II Corps and XIX Corps reached the outskirt of Lanzhou.On August 21, 1949, a total of nine regiments from the communist II Corps and XIX Corps attacked the nationalist stronghold at Southern Mountain outside Lanzhou, but were beaten back with heavy losses after two days of fierce fighting.The communist commander Peng Dehuai decided to call off the attack and regroup so lessons gained in the fighting could be learned and utilized for the following assaults.