Gai Yu

Gai Yu (died 905), formally the Duke of Chengyang , was a key strategist of Li Keyong, a major warlord late in the Chinese Tang dynasty.

Background It is not known when Gai Yu was born, but it was known that he was from Wei Prefecture (蔚州, in modern Zhangjiakou, Hebei), and that both his grandfather Gai Zuo and father Gai Qing served as officer at Wei Prefecture. When the ethnically-Shatuo officer Li Keyong rose against Duan Wenchu the defender of Datong Circuit (大同, headquartered at Datong, Shanxi) (which Wei Prefecture belonged to) at Datong's capital Yun Prefecture in 878, Gai was one of the proponents, and he became a close associate of Li's. he made Gai Yu a base supervisor as well as the prefect of Lan Prefecture (嵐州, in modern Lüliang, Shanxi). After Li Keyong was later made the military governor of Hedong Circuit (河東, headquartered in modern Taiyuan, Shanxi), Gai continued as a base supervisor. It was said that Li Keyong consulted him on all important matters and listened to his suggestions, and that he accompanied Li Keyong on all campaigns.

In 894, Gai suggested that Li Keyong support the former Lulong Circuit (盧龍, headquartered in modern Beijing) officer Liu Rengong, who had fled to Hedong after an unsuccessful attempt to take over the circuit, in his endeavors to capture the circuit against Li Kuangchou. Li Keyong agreed, and after a campaign against Li Kuangchou took over Lulong and gave it to Liu to rule as his vassal. (However, Liu would betray Li Keyong in 897 and became independent.)

In 895, Li Keyong waged a successful campaign against Wang Xingyu (who had succeeded Zhu as the military governor of Jingnan) and Li Maozhen, the military governor of Fengxiang (who had succeeded Li Changfu) after they had marched on Chang'an and killed the chancellors Li Xi and Wei Zhaodu.Then-reigning Emperor Zhaozong (Emperor Xizong's brother and successor) created Li Keyong the Prince of Jin and bestowed many titles on his followers. As part of this, Gai was made the governor (觀察使, Guanchashi) of Rong District (容管, in modern Yulin, Guangxi), but did not actually report there. After Li Keyong's son and successor Emperor Zhuangzong of Later Tang founded Later Tang, he gave Gai posthumous honors.