Liu Yu 劉裕, Emperor Wu of the Liu-Song dynasty 宋武帝

Liu 劉裕 (363-422; Emperor Wu 宋武帝, r. 420-422), courtesy name Deyu 德輿, from Pengcheng 彭城 (today's Xuzhou 徐州, Jiangsu), was the founder of the Liu-Song dynasty 劉宋 (420-479), the first of the Southern Dynasties 南朝 (420-589).

He grew up under poor conditions as his father had passed away early. His career started in the stables under commander Sun Wuzhong 孫無終 (d. 403) of the Army of the Northern Headquarters (beifubing 北府兵). In 399, he became Vice Commander (canjun 參軍) of Fore General (qian jiangjun 前將軍) Liu Laozhi 劉牢之 (d. 402) and participated in the suppression of the rebellion of Sun En 孫恩 (d. 402). For his military achievements, Liu Yu was made General Establishing Martiality (jianwu jiangjun 建武將軍) and appointed governor (taishou 太守) of the commandery of Xiapi 下邳. Under the regime of Huan Xuan 桓玄 (369-404), Liu was entrusted with the elimination of the last groups of Sun En, yet while openly complying to the usurper's commands, Liu made ready his troops for fighting against Huan.

In 404, when Huan Xuan forced Emperor An 晉安帝 (r. 396-418) to retire, Liu Yu united his forces with that of Liu Yi 劉毅 (d. 412), He Wuji 何無忌 (d. 410) and Tan Pingzhi 檀憑之 (d. 403) and killed the commander of the critical garrison of Jingkou 京口, Huan Xiu 桓修 (d. 404). In the next year, they conquered the capital Jiankang 建康 (present-day Nanjing 南京, Jiangsu) and forced Huan Xuan to flee to Jiangling 江陵, but the usurper took the rightful emperor with him. Liu Yi finally liberated the sovereign and received him back in the capital. Liu Yu was given the title of Palace Attendant (shizhong 侍中), General of Chariots and Cavalry (cheji jiangjun 車騎將軍 and Commander Unequalled in Honour (kaifeng yitong sansi 開府儀同三司), and was given the command over Jingkou. In 408, he was given the post of regional inspector (cishi 刺史) of the province of Yangzhou 揚州 and that of Overseer of the Imperial Secretariat (lu shangshu shi 錄尚書事), which made him the regent of the Jin empire. Liu Yu was soon awarded the position of Commander-in-chief (dudu 都督) of sixteen provinces and made regional inspector of Qingzhou 青州, Xuzhou 徐州, and Yanzhou 兗州, and was invested as Commandery Duke of Yuzhang 豫章郡公.

The non-Chinese empire of the Southern Yan 南燕 (398-410), which controlled the Shandong Peninsula, used the internal turmoils of the Jin empire to invade Jin territory. In 409, Murong Chao 慕容超 (r. 405-410) advanced to the Huai River 淮河 region. Liu Yu took over the defense campaign and set off with a fleet from Jiankang. A year later, he destroyed the Southern Yan capital in Chenggu 廣固 (today's Yidu 益都, Shandong) and reconquered the provinces of Qingzhou and Yanzhou. In 411, Liu Yu suppressed the rebellion of Lu Xun 盧循 (d. 411). In the next year, he annihilated the forces of Liu Yi, Zhuge Changmin 諸葛長民 (d. 413) and Sima Xiuzhi 司馬休之, the Prince of Qiao 譙 (d. 417). These persons were not such much threats for the Jin dynasty, but challengers of Liu Yu's own power.

In 413, he attacked Qiao Zong 譙縱 (d. 413) in the west and conquered the region of Shu 蜀 and Ba 巴 (today's Sichuan). This allowed him to launch in 416 a war in the western region to attack the empire of Later Qin 後秦 (384-417) in the Guanzhong region 關中. He liberated Chang'an 長安 (present-day Xi'an 西安, Shaanxi) and Luoyang 洛陽 (in today's Henan province). On the way back along the Yellow River, he also defeated an army of the Northern Wei empire 北魏 (386-534).

At that time, the resident regent (liushou 留守), Left Vice Director of the Imperial Secretariat (shangshu zuo puye 尚書左僕射), Liu Muzhi 劉穆之 (360-417), died. Liu Yu feared that machinations in the capital would put him in a disadvantageous position. He thus left his son Liu Yizhen 劉義真 (407-424) in Chang'an, supported by strong army units, and returned to Jiankang. Even if Chang'an fell into the hands of the Xia empire 夏 (407-431), Liu Yu was highly rewarded back at the court in Jiankang. He was made Counsellor-in-chief (xiangguo 相國), obtained the Nine Privileges (jiuxi 九錫) and was awarded the title of Duke of Song 宋公.

In early 419, Liu Yu had Emperor An killed and made Emperor Gong 晉恭帝 (r. 418-419) ruler, who in turn invested Liu Yu as King of Song 宋王. In 420, Liu Yu forced Emperor Gong to abdicate (shanrang 禪讓) and founded his own imperial dynasty, the Song, and proclaimed the reign motto Yongchu 永初. Not long after the enforced abdication, Liu Yu had Emperor Gong killed.

As a man of humble origins, Liu Yu knew how the gentry elite (see menfa 門閥) exploited the poor, and thus fought against hidden households and illegal opening of fields. The land reform he had carried out in some cases bore traits of personal revenge, for instance, the expropriation and murder of Diao Kui 刁逵 (d. 404), who once had humiliated Liu Yi in his youth. He also reduced the size of the exile provinces, commanderies and districts (see qiaozhou 僑州) to strengthen the central government's control of land and resources. For the recruitment of competent state officials, he personally carried out the selection of candidates from the provinces and commanderies.

After a short reign, Liu Yu died, and was buried in the tomb hill Chuning 初寧陵. He was succeeded by his oldest son, Liu Yifu 劉義符 (406-424), who is known as the Infant Emperor 宋少帝 (r. 422－424). Liu Yu's posthumous title is Emperor Wu 宋武王, and his temple name Emperor Gaozu 宋高祖.