Zhang Xueliang
Zhang Xueliang succeeded Zhang Zuolin as leader of the Fengtian clique, and decided to end the war and to co-operate with the nationalists. The Shandong–Zhili Army led by Zhang Zongchang and Chu Yupu refused to surrender, and despite the defeats it had suffered still numbered about 60,000–70,000 soldiers, as well as at least three armoured trains manned by White Russian mercenaries under General Konstantin Nechaev. As Zhang Xueliang had sided with the nationalists, Zhang Zongchang declared war on the Fengtian clique. Supported by Japan, the Shandong–Zhili Army moved from its base at Tangshan on 2 August, crossed the Luan River, and invaded Manchuria. After six days of fighting, however, the defiant warlord army was trapped by KMT and Zhang Xueliang-aligned forces; many of Zhang Zongchang's troops (including the White Russian mercenaries) defected or deserted, and those who refused to surrender were killed. Zhang Xueliang officially declared his allegiance to the nationalist government in Nanjing on 29December 1928, marking the formal end of the Northern Expedition, and the reunification of China.