Liu Wu () (died September 25, 825), formally the Prince of Pengcheng (), was a Chinese military general, monarch, and politician during the Tang Dynasty, whose killing of his superior, the warlord Li Shidao, and subsequent submission to the imperial government, were the high point of Emperor Xianzong's campaign to end warlordism. During the subsequent reign of Emperor Muzong, however, Liu, angered by a conspiracy between an imperial eunuch and one of his subordinates, drifted away from the imperial government and ruled Zhaoyi Circuit (昭義, headquartered in modern Changzhi, Shanxi) semi-independently.
Background
It is not known when Liu Wu was born. His grandfather Liu Zhengchen () had served as the Tang military governor (Jiedushi) of Pinglu Circuit (平盧, then headquartered in modern Chaoyang, Liaoning) during the Anshi Rebellion and combatted the army of the rebel Yan, but was unable to capture the Yan northern capital Fanyang before being poisoned by his own subordinate Wang Xuanzhi (). During the time that Liu Wu's uncle Liu Quanliang () served as the military governor of Xuanwu Circuit (宣武, headquartered in modern Kaifeng, Henan), as he valued Liu Wu for Liu Wu's bravery and decisiveness, he made Liu Wu an officer under him, but Liu Wu subsequently committed a crime and fled to Zhaoyi Circuit (昭義, headquartered in modern Changzhi, Shanxi), where the military governor of Zhaoyi, Wang Qianxiu (), made him an officer. Liu Wu soon became ill and resigned, and he went to the eastern capital Luoyang. Liu Quanliang had a storage of money at Luoyang, and Liu Wu broke into it and spent it. Liu Wu also associated with violent young men who killed people and dogs. As a result, Liu Wu was arrested and held at the jail of Henan Municipality (河南, i.e., the Luoyang region), but the defender of Luoyang Wei Xiaqing () released him.
Service under Li Shigu and Li Shidao
Liu Wu subsequently fled to Pinglu Circuit (by this point headquartered in modern Tai'an, Shandong) to serve under the military governor Li Shigu, who ruled the circuit in de facto independence from the imperial government. Liu was not initially well known in the Pinglu army. On one occasion, when the officers were playing polo, his horse charged Li Shigu's horse, causing Li Shigu's horse to fall. Li Shigu, in anger, was set to execute him. Liu responded with proud words without fear. Li Shigu was amazed and pardoned him, and found a wife for him. He thereafter was promoted several times, until he became army commander (兵馬使, Bingmashi).
In 818, after Emperor Xianzong declared a general campaign against Li Shigu's brother and successor Li Shidao, Li Shidao had Liu command troops to defend against imperial armies' attack, in position at Cao Prefecture (曹州, in modern Heze, Shandong). It was said that Liu was lenient and simplified the military laws, and as a result the soldiers were happy to be under his command — such that he was referred to as "Father Liu." After Tian Hongzheng the military governor of Weibo Circuit (魏博, headquartered in modern Handan, Hebei) crossed the Yellow River and pressured Pinglu's capital Yun Prefecture () directly in winter 818, Liu stationed his army at Yanggu (陽穀, in modern Liaocheng, Shandong) to defend against Tian. Tian's army repeatedly prevailed over Liu's, and there were accusations by some of Li Shidao's associates that Liu was plotting against him. Li Shidao thus summoned Liu back to Yun Prefecture under the guise of a strategic meeting but planned to execute him. Yet other associates of Li Shidao's counseled that if he put Liu to death without proof of treachery, no one would remain faithful to him. After keeping Liu at Yun Prefecture for 10 days, Li Shidao ordered him to return to Yanggu and gave him gifts to try to secure his loyalty. However, because Liu Wu's son Liu Congjian served in Li Shidao's guard corps, he found out about what Li Shidao had originally intended and reported it to Liu Wu, so Liu Wu secretly took precautions.
