 Around this time, Emperor Wen also started preparing for a campaign against rival Northern Wei, seeking to recover several provinces lost to Northern Wei during the reign of Emperor Shao.In spring 430, he put Dao Yanzhi in command of a 50,000-man army to attack Northern Wei.Emperor Taiwu of Northern Wei, when informed by Emperor Wen's messengers that all Emperor Wen was interested in was to recover the provinces south of the Yellow River, retorted angrily that he would withdraw but return in the winter once the Yellow River froze, and that was what he initially did—withdrawing his armies south of the Yellow River to areas north, allowing Liu Song to recover the four key cities of Luoyang, Hulao, Huatai (滑台, in modern Anyang, Hunan), and Qiao'ao (碻磝, in modern Liaocheng, Shandong) without a fight.