 Meanwhile, Yuwen, after killing Emperor Yang, had advanced north with Sui's elite Xiaoguo Army (), and he had, after first declaring Emperor Yang's nephew Yang Hao emperor and then poisoned Yang Hao and been several times defeated by Li Mi and then the Tang general Li Shentong (李神通, Emperor Gaozu's cousin), declared himself Emperor of Xu and settled in at Liaocheng (聊城, in modern Liaocheng, Shandong).In spring 619, Dou proclaimed, "I was a Sui subject, and the Sui emperor was my lord.Yuwen Huaji killed my lord, and is therefore my enemy, and I must attack him."