The Eastern Jin Dynasty was a weak dynasty, the powerful ministers Wang Dun, Huan Wen, Huan Xuan, Liu Yu and other people all had disobedient hearts, of which Wang Dun failed, Huan Wen died of illness before he had time to usurp the throne, his son Huan Xuan deposed Emperor Huan of Jin to establish the Huan Chu regime, after a handful of emperor addiction, but only two years after the defeat and killing of soldiers, the real success was Liu Yu: in 419 Liu Yu killed Sima Dezong, the emperor of Jin'an, and established his half-brother Sima Dewen as emperor, known as Emperor Gong of Jin; in June of the following year (420), Sima Dewen Zen was located in Liu Yu, and the Eastern Jin Dynasty fell, In September of the same year, Liu Yu killed Emperor Gong of Jin again.
Two hundred years ago, in 220, the last emperor of the Eastern Han Dynasty, Liu Xiechan, gave the throne to Cao Pi, and in 265 years ago, the late emperor of Cao Wei, Cao Yichan, gave the throne to Sima Yan, but Liu Xie and Cao Yi both received good treatment after taking the throne, such as Cao Pi sealing Liu Xie as the Duke of Shanyang and eating all households; Sima Yan made Cao Huan the King of Chen Liu, and also ate all households, and both of them were able to die well, so why did he come to Liu Yu here, but he had to kill Emperor Jin'an first, and then kill Emperor Gong of Jin to cut the grass and remove the roots? The reasons are not complicated.
First, Liu Yu was born in 363, 419 is already 56 years old, the age of nearly 60 years old for Liu Yu in the life of Rong Ma has a sense of urgency that time is not waiting, more importantly, Liu Yu has a son, in 406 he only had his eldest son Liu Yifu when he was 43 years old, that is to say, in 419 his eldest son was only 13 years old (many people will return to the south in a hurry after Liu Yu attacked Chang'an in 417 because of Liu Mu's illness, why did he leave Liu Yizhen, who was only 11 years old, to guard Chang'an?). Liu Yu was forced to be helpless, because Liu Yizhen was the second son, and the other sons were younger).
He was old, his sons were still young, and if one day he drove the crane west, sima clan might still make a comeback, so Liu Yu not only killed Emperor An of Jin and Emperor Gong of Jin, but even the Sima clan royal family in Jiankang was all slaughtered by him, and Liu Yu's starting point was rough and simple, that is, to cut the grass and remove the roots, so as to avoid future troubles.
Second, the Eastern Jin Dynasty has been established for more than a hundred years, although weak but still has considerable appeal in the government and the opposition, huan chu dynasty Jin dynasty more than ten years ago is very unpopular also shows this, and the eastern Jin dynasty door valve politics is deeply rooted, with the Presence of the Sima Clan, the family clan is still likely to unite around the Sima Clan.
Another difference is that whether it is Cao Wei Dynasty Han or Western Jin Dynasty Wei Dynasty, there was a relatively long period of preparation and accumulation before this, such as Cao Wei had two generations of Cao Cao and Cao Pi, Sima Shi had Sima Yi, Sima Shi and Sima Zhao, Sima Yan three generations of management, the government and the public are basically their own people, and Liu Yu is different, the self-made foundation is not deep, the imperial court is not a monolith, which is also the reason why Liu Yu returned to Jiankang in a hurry after hearing of Liu Muzhi's illness and death after he attacked Chang'an.
Third, before killing Emperor An of Jin and Emperor Gong of Jin, Liu Yu had already killed two emperors: one was the first Northern Expedition in 410 to attack Southern Yan, and the late Southern Yan emperor Murong Chao was escorted to Jiankang and beheaded in the street market; the other was the second Northern Expedition in 417 to attack Later Qin, and the late Qin emperor Yao Hong was also beheaded in the downtown area of Jiankang.
For Liu Yu, killing the emperor was not the first time, and there was no difference between killing Emperor An of Jin and Emperor Gong of Jin and killing Murong Chao and Yao Hong, which was another reason why Emperor An of Jin and Emperor Gong of Jin died.
As for saying that Liu Yu killed Sima Shi in order to avenge Liu Shi (Liu Yu was after Liu Jiao, the King of Chu yuan in the Western Han Dynasty), this reason is a bit far-fetched.