Warlord Counteroffensive
The purge gave the warlords an opportunity to rebuild their armies and counter the now weakened Kuomintang. Sun Chuanfang began to marshal his forces with his ally Xu Kun, one of China's best generals. At the same time, Sun was communicating with Zhang Zuolin of Manchuria, requesting assistance of any kind in the hopes of regaining his lost territory, including Nanking. He brought up an army of one hundred thousand men and arranged them around the Lower Yangtze River. His plan was to begin an all-out attack upon the Nationalist forces of Chiang, Li Zongren and Bai Chongxi, drive them away from the Yangtze and Nanking and pursue them southward back into Guangzhou, where the expedition had started.
Opposing the rejuvenated warlord armies were three Kuomintang Armies, referred to as the "Route Armies". The First Route Army, north of Nanking in Jiangsu Province; the Second Route, to the west of the First and centered around the city of Xuzhou, and the Third on the west of Xuzhou closer to Wuhan in the South, protecting against any intervention by the Leftist Wuhan forces. The Nationalists could afford to muster the same amount of manpower but was very divided by political tensions and leadership conflicts. Yet, it was the element of surprise that gave Sun and Xu Kun the advantage for their attack was not fully expected by Chiang or his military commanders. Finally, the Nationalists had stationed many of their troops on the northern side of the Yangtze in order to hold Xuzhou, leaving them exposed to the warlord armies and their impending counteroffensive. Thus, Chiang had sent a large number of troops into positions in which they could neither defend properly, without the combined support of the army, nor defend with any real purpose, setting the stage for the last great struggle of the Warlord Era.
Sun Chuanfang, on July 24, ordered the counterattack to begin. His army, including Xu Kun's forces, tore through the surprised Nationalist forces, resulting in the loss of Xuzhou in northern Jiangsu province. The Second Route Army, stationed in the area, was forced to withdraw south, using the Long-Hai railway as an escape route. The other Route Armies also began to retreat south toward the Yangtze as the warlord armies routed any remaining troops in their path. Chiang, who was astounded to hear that Xuzhou had fallen, sacked the army's commander, Wang Tianpei, and ordered that Xuzhou be retaken. Against the advice of Li Zongren, who thought it was better to withdraw south, Chiang, having exclaimed, "I will not return to Nanking until Xuzhou is back in our possession". He launched his attack with the Second Route Army in August, resulting in a terrible defeat for the Nationalists. This defeat led to Chiang's immediate resignation on Aug. 6th as head of the Nanking Government, prompting him to move to Shanghai, where his loyal supporters followed. Following this, Li Zongren and other military leaders evacuated the whole army to the Yangtze with the principal goal of defending Nanking.
Read more about this topic: Northern Expedition