By 1 April, Feng's NRA Second Collective Army ("Guominjun") and Yan's NRA Third Collective Army had started to fight the NPA on the Henan–Shandong border and along the Beijing–Suiyuan railway. The resumption of the Northern Expedition was officially launched by Chiang Kai-shek on 7 April. With the NPA line softened by Feng and Yan's attacks, the NRA First Collective Army rushed into Shandong along the Tianjin–Pukou railway, capturing Tengzhou by 16 April. Meanwhile, Feng's forces advanced into Shandong from the west, capturing Jiaxiang on the 15th. Sun Chuanfang decided to attempt a two-pronged counter-offensive against the NRA First and Second armies, managing to push the First back to the Longhai railway. His attack against the Second Army failed, and by the 21st, the combined NRA had forced him to withdraw from Jining to the provincial capital Jinan. According to an American account Sun's retreat, the "great majority of the troops in this retreat literally walked the soles off their shoes, and this, combined with the scarcity of food and total lack of shelter left the vast horde without any idea of further resistance". The Japanese, meanwhile, having heard of Sun's defeat, began to move Kwantung Army troops by train from Qingdao to Jinan.