Cheng Rui

Cheng Rui (成汭 died June 10, 903[1][2]), adoptive name Guo Yu (郭禹 used until c. 888), formally the Prince of Shanggu (上谷王), was a warlord late in the Chinese Tang dynasty who ruled Jingnan Circuit (荊南 headquartered in modern Jingzhou, Hubei) from 888 to 903, until he was defeated in battle.

He became a Buddhist monk for a while, but later joined as a soldier under Tang rebel general Qin Zongquan at Cai Prefecture (蔡州, in modern Zhumadian, Henan).

[3] At a later point, Guo Yu left Qin's army and became a bandit in Huomen Mountain (火門山, in modern Tianmen, Hubei).

[6] In 896, Cheng Rui and his officer Xu Cun (許存) headed upstream (west) on the Yangtze River and attacked Wang Jianzhao, whom Emperor Zhaozong had made the military governor of Wutai Circuit (武泰, headquartered at Qian Prefecture).

However, Cheng made another officer, Zhao Wu (趙武), the acting military governor of Wutai, while only making Xu the prefect of Wan Prefecture (萬州, in modern Chongqing).

[3] At some point, Cheng complained to the imperial government that the warlord Lei Man was occupying Li (澧州) and Lang (朗州) Prefectures (both in modern Changde, Hunan), both of which formerly belonged to Jingnan, and requested that those prefectures, which had been made into a separate Wuzhen Circuit (武貞) to accommodate Lei, be returned to Jingnan.

Du sought aid from Zhu Quanzhong the military governor of Xuanwu Circuit (宣武, headquartered in modern Kaifeng, Henan), who was then the most powerful warlord in the Tang realm.

Zhu sent his officer Han Qing (韓勍) to try to aid Du, but apparently judging his army to be insufficient, also sent emissaries to Cheng, Ma Yin the military governor of Wu'an Circuit (武安, headquartered in modern Changsha, Hunan), and Lei Man's son and successor Lei Yanwei, asking them to save Du.

Cheng, who was both apprehensive of Zhu's strength and wanting to expand his own territory, put together a huge fleet of some 10,000 men and headed east on the Yangtze.

Instead, Li advised that Cheng send a smaller army to Baling (巴陵, in modern Yueyang, Hunan) to try to intimidate the Huainan forces into withdrawing, without committing the main fleet.