Which emperor had killed close relatives to ascend the throne?
HAN DYNASTY
Emperor Cheng was unable to produce a son with his Empress or his many concubines. The Empress Dowager Wang was desperate for a grandson that could inherit the throng. Cheng eventually took on many more concubines including to two dancing girls who were sisters, Zhao Feiyan and Zhao Hede. Cheng favored them over his wife and the Zhao sisters eventually falsely accused Empress Xu and Consort Ban of witchcraft. Empress Xu was disposed though the Empress Dowager refused to allow a marriage of one of the sisters to Cheng due to their low class standing.
It is suspected that Consort Zhao Hede murdered two sons that Emperor Cheng had with two other concubines. This was done possibly out of jealousy, according to a report commissioned by Empress Dowager Wang. The boys were killed in their infancy and one of their mothers, Consort Cao committed suicide not long after her son was killed. These murders were done with the agreement of Emperor Cheng who eventually named his nephew the Crown Prince(History - Historical Figures. Son Emperor Cheng's "Women Troubles" and Lack of Heir).
SUI DYNASTY
Though there was no accusations at the time and still no concrete evidence, it is still hightly suspected that Emperor Yang ordered the death of his father, Emperor Wen. A detailed account of Emperor Wens last days is given by Zizhi Tongjian who says that Yang tried to have sex with one of Emperor Wen's consorts and when she reported the incident to the Emperor he was furious. Interestingly enough, Yang took her and another of Wen's consorts as his own concubines not long after he inherited the throne. The theory that Yang killed Wen came years after but there are major inconsistencies in that story, including a change in which concubine Yang tried to seduce. However, the theory has been passed on in Chinese culture for so long that is often mistaken to be historical fact. In all likelihood we will never known for sure if murder was the cause of Emperor Wen's death. (History - Historical Figures." Did Emperor Yang Kill Emperor Wen?).
Before his death, Eperor Wen himself had actually secured his position as Emperor by deposing the current Emperor, who was a child of only six years old (New World Encyclopedia). However, it is also speculated that he killed dozens of other potential Princes who help claim to the throne in order to protect his position (Reunification Under the Sui Dynasty).
TANG DYNASTY
Emperor Gaozu helped overthrow Emperor Yang of Sui. After many years of preparation and fighting, Yang was killed during a coup but not by Gaozu himself.
Li Shimin, later known as Emperor Taizang(599-649) led an insurrection against his father, Emperor Gaozu. He had assisted during the rebellion against the Sui and had a impressive military background. Despite this, his older brother, Li Jiancheng, was named crown price. However, as fighting in other parts of China escalated, Li Shimin was the one sent to fight. The capitol eventually began to split into factions, though loyal to Li Shimin and those to the crown prince. The rivalry increased through the years and Li Jiancheng is suspected of an assassination attempt against Li Shimin at least once. Li Shimin eventually ambushed his older and younger brother, killed them, as well as their sons to ensure they could not threaten his place on the throne. Li Shimin deposed his father and became Emperor in the year 626 (source: Taizong of Tang Dynasty). He did not kill Gaozu, who “lived on as Grand Emperor (Taishang Huang) until his death in 635" ("Li Yuan").
MING DYNASTY
Emperor Jiajing (1507-1567) was known for his cruelty. When he came into power he had those who disagree with him beaten, tortured, killed, or exiled (Britannica). He was also violent against his many concubines. Eventually, eighteen of them planned to kill him while he slept. Using a hair ribbon they tied it around his neck but after putting a knot in it, they could not pull it tight enough to suffocate him. One of the girls lost her nerve and ran to the Empress who raised the alarm. All the girls were put to death threw the long, painful and dishonorable process of Lingchi ("Beijing History"). The concubines families were also killed as punishment for their crime.
QING DYNASTY
Emperor Yongzheng was the fourth son of at least fourteen and the eldest born by the Empress. when the previous Emperor renounced Yongzhengs older brother after a scandal he did not name a new heir. A rivalry started between several of the sons, fighting for support and power from people in the capitol. It is widely believed that Yongzheng poisoned his father and then changed the will from the "14th son should inherit" to the "4th son should inherit" (source: Yongzheng). The murder has never been proven and historians do not believe the will could have been changed so easily("Yongzheng").
After becoming Emperor, Yongzheng proceeded to arrest many of his brothers(Spence, p 74). The former heir apparent and two other brothers died in prison but it is unknown if they were murdered or not (Spence, p 74). Another sourcesays that Emperor Yonngzheng had all but one of his brothers killed ("Beijing History").
Empress Dowager Cixi (1835-1908) was rumored to have killed many of her family members. She took control of Emperor Tongzhi as he was a young Emperor and supposedly had him poisoned in 1875 when he was 19 years old. It is more widely believed now that he died of smallpox(Paludan). She then proceeded to persuade the pregnant wife of Tongzhi, Alute, to commit suicide by eating gold dust two months after Tongzhi's death in order to put her nephew Guanxu on the throne (Pakula). Guanxu was only four years old when put on the throne and therefore easily controled by Cixi. One murder the Empress definitely committed was that of her nephew, Emperor Guanxu, who she killed with arsenic in 1908. Empress Dowager Cixi died 22 hours after her nephew of old age. It is possible that Cixi knew of her approaching death and had Guanxu killed so he could not continue the reforms he had put in place ("Arsenic Killed Chinese Emperor").
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