In 348, after he led a failed campaign against the collapsing Later Zhao with major losses, Chu Pou died in humiliation. During the next few years, however, without major campaigns on Jin's part, many of Later Zhao's southern provinces switched their allegiance to Jin, but not firmly so. Huan repeatedly requested permission to march north, but was constantly rebuffed by Sima Yu and Yin, who were concerned that he would be even harder to control if he recovered central and northern China for Jin.