Emperor Xian of Han
Cao Cao died on 15 March 220. His son and successor, Cao Pi, soon forced Emperor Xian to abdicate the throne in favour of himself, ending the Han dynasty. Cao Pi established a new state known as Cao Wei (sometimes known inaccurately as the Kingdom of Wei), and he granted Emperor Xian a noble title – Duke of Shanyang (山陽公). The former Emperor Xian died in 234 and was buried with honours befitting an emperor, using Han ceremonies, and the then emperor of Wei, Cao Rui, was one of the mourners. As Emperor Xian's crown prince was already dead, his grandson Liu Kang (劉康) inherited his dukedom, which lasted for 75 more years and two more dukes, Liu Jin (劉瑾) and Liu Qiu (劉秋), until the line was exterminated by invading Xiongnu tribes in about 309, during the Jin dynasty. This practice of an emperor conferring hereditary nobility on his predecessor, from whom he usurped the throne, was known as "er wang san ke" (二王三恪).
List of emperors of the Han dynasty
At times, especially when an infant emperor was placed on the throne, a regent, often the empress dowager or one of her male relatives, would assume the duties of the emperor until he reached his majority. Sometimes the empress dowager's faction—the consort clan—was overthrown in a coup d'état. For example, Empress Lü Zhi (d. 180 BC) was the "de facto" ruler of the court during the reigns of the child emperors Qianshao ("r". 188–184 BC) and Houshao ("r". 184–180 BC). Her faction was overthrown during the Lü Clan Disturbance of 180 BC and Liu Heng was named emperor (posthumously known as Emperor Wen). Before Emperor Wu died in 87 BC, he had invested Huo Guang (d. 68 BC), Jin Midi (d. 86 BC), and Shangguan Jie (上官桀)(d. 80 BC) with the power to govern as regents over his successor Emperor Zhao of Han ("r". 87–74 BC). Huo Guang and Shangguan Jie were both grandfathers to Empress Shangguan (d. 37 BC), wife of Emperor Zhao, while the ethnically-Xiongnu Jin Midi was a former slave who had worked in an imperial stable. After Jin died and Shangguan was executed for treason, Huo Guang was the sole ruling regent. Following his death, the Huo-family faction was overthrown by Emperor Xuan of Han (r. 74–49 BC), in revenge for Huo Guang poisoning his wife Empress Xu Pingjun (d. 71 BC) so that he could marry Huo's daughter Empress Huo Chengjun (d. 54 BC).