As the two sides attempted to reconcile their political differences, Sun Chuanfang's forces continued to bombard Nanjing from across the Yangtze. Sensing the NRA's continual disarray, Sun moved to try and recapture Shanghai, contrary to the wishes of NPA leader Zhang Zuolin. On 25 August, NPA landing parties were dispatched to cross the Yangtze at Longtan, near Nanjing. In the early morning of 26 August, thousands of Sun's troops crossed the river, rallying at the Longtan station of the Shanghai–Nanjing railway. Li Zongren's NRA Seventh Army managed to drive the NPA away from the railway briefly, but thousands more of Sun's troops, including White Russian mercenary units, crossed the river the next day and retook the station, cutting off contact between Nanjing and Shanghai. The reeling NRA sent missives to all factions within the revolutionary movement, calling for unity in the face of Sun's advancing troops. Accordingly, in an attempt to put pressure on Sun, Feng Yuxiang and his "Guominjun" launched an attack into Shandong on 28 August, while Wuhan sent its troops north, trying to flank Sun, and He Yingqin approached from Shanghai. With its forces encircled, and unable to continue to move troops across the river, the NPA was forced to abandon Longtan railway station on 30 August. In a desperate attempt at resistance, Sun rallied his 40,000 remaining troops and launched a counter-offensive on 31 August, only to be crushed in a hard-fought battle that left more than 10,000 of those troops dead. While Sun was able to escape to Shandong, his surviving troops were forced to surrender to NRA.