Fourth Field Army
After the end of Pingjin campaign, the I Corps, II Corps, and III Corps of the communist North China Military Region were renamed as the XVIII Corps, XIX Corps, and XX Corps respectively, while the 7th Column of the communist Northwest Field Army was renamed as the 7th Army of the First Field Army. In March, 1949, the communist XIX Corps, XX Corps, an artillery division of the Fourth Field Army and another artillery division of the communist North China Military Region were sent to Taiyuan to assist the communist XIX Corps in taking the city. On March 17, 1949, the communists formed the Taiyuan Frontline Command headed by Xu Xiangqian to coordinated the upcoming attack on the city, and Xu was further assisted by Peng Dehuai when he joined the Xu on March 28, 1949. The total communist force totaled more than 320,000, achieving absolute numerical superiority. However, the communists soon realized that due to the mountainous terrain of Taiyuan that strongly favored the defenders, the increased number of communist troops only provided excellent target practice for the defenders of the city because the harsh terrain had prevented large number of attacking force from being deployed in great numbers. In order to avoid wasteful casualties, the communists were forced to reduce their attacking force back to the original level of 100,000 troops in the first stage of the Taiyuan campaign while the rest were deployed as reserves. However, the newly boosted force did provide a welcome relief for communist veterans of the first stage of the campaign, and they were replaced by the fresh communist forces newly arrived.