李存勗
In the late 910s, Li Cunxu had the trusted eunuch Li Shaohong and the official Meng Zhixiang (the husband of his cousin, who would later receive the title of Grand Princess Qionghua during his reign as emperor) serving as his chiefs of staff (中門使, "Zhongmenshi"). At Meng's recommendation, Guo was made the deputy chief of staff in 917. When the major general Zhou Dewei the military governor of Lulong Circuit (盧龍, headquartered in modern Beijing) died in battle in 918, Li Cunxu was forced to take over the command of Lulong himself and dispatch Li Shaohong to Lulong to actually take control. As prior chiefs of staff had often received punishment from Li Cunxu, however, Meng did not want to remain chief of staff, particularly by himself and wished to resign the post. Li Cunxu required him to nominate a successor, and Meng recommended Guo. Li Cunxu accepted the recommendation, and made Guo the chief of staff. It was said that thereafter, Guo became in charge of the affairs of Li Cunxu's headquarters and followed Li Cunxu through his campaigns against Later Liang.