As we all know, Sima Yi seized Cao Wei's Jiangshan through the Gaopingling coup, which also laid the foundation for Sima Yan to replace Wei in the future. In fact, Sima Yi's road to usurpation was not so smooth, he had been suppressed successively when the three generations of Cao monarchs were in power, if it were not for Cao Fang's youth, Sima Yi would have had a hard time usurping the Cao family.
The Sima family was a major prominent family in Jizhou, and when Cao Cao was in power, Sima Yi was used heavily, because of the position of the Sima family in the clan class, so Cao Cao also had to choose to use Sima Yi. Sima Yi's father, Sima Fang, was a major minister of the Eastern Han Dynasty, and during the reign of Emperor Xian of Han, Sima Fang was Jing Zhaoyin. Sima Fang had eight sons, of which Sima Yi was the most prominent.
Among Sima Yi's brothers, Sima Lang served as the Assassin of Yanzhou in the State of Wei, Sima Ke was the Secretary of the Hongxu Temple, and Sima Yi once held the position of Tai wei (太尉) of the State of Wei. Whether it was during the reign of Cao Cao or during the reign of Emperor Wen of Wei and Emperor Ming of Wei, Sima Yi could be counted as a major vassal of the State of Wei. So, how did Sima Yi usurp the Wei state? Why is it difficult for Cao Fang to restrain the rise of Sima Yi?
Sima Yi was not taken seriously by Cao Cao at first, and before the Battle of Chibi, Sima Yi had been living in seclusion at home. At that time, although Sima Yi was already famous in the world, it seemed that he had no intention of entering the world. It was not until Cao Cao personally summoned him that he went out to assist Cao Shi. Sima Yi initially held only the position of literary scholar, which was only a fictitious title and had no actual rights, but later, he was valued by the future Wei Emperor Cao Pi before he decided to assist Cao Pi in his great cause.
Cao Cao and Cao Pi's father and son had great trust in Sima Yi, and when Cao Cao was in power, he had already discovered Sima Yi's talents. On the eve of the Battle of Jingzhou, Guan Yu flooded the Seventh Army, because of the tension of the war, Cao Cao actually did not have a good strategy for a while, and it was Sima Yi who put forward the idea of alliance with Wu at this critical moment, which contributed to the situation of Eastern Wu's attack on Jingzhou. From this point of view, Sima Yi was still a hero who saved The Cao Army.
Sima Yi's usurpation of government was forced out, not innate, and in the process of Cao Pi and Cao Zhi competing for the position of shizi, Sima Yi had already discovered the sinister nature of politics, that is, from this time on, this spirited talent gradually became old and vicious. Sima Yi was still loyal to Cao Pi, and with his strong support, Cao Pi eventually built Wei on behalf of Han.
The change in Cao Pi's attitude toward Sima Yi was due to a change in identity, in the past, when Cao Pi was the son of the world, Sima Yi and Cao Pi were close friends, but now that Cao Pi was a son of heaven, he had to regard it as a courtier. Cao Pi's control of Sima Yi was the same as other emperors in history, which was the embodiment of the emperor's instinct and did not go out of line.
Sima Yi in the Wei Wen Emperor, Ming Emperor two dynasties, can be counted as loyal subjects, during this period, Sima Yi did not have the ambition to usurp the government, although Emperor Wen and Emperor Ming also had suspicions about it, but after all, did not move to kill, so, the two civilized dynasties, Sima Yi did not have to worry about his life.
The State of Wei moved into the period of Cao Fang, the King of Qi, but this situation underwent a fundamental change, Cao Shuang, the prince of Cao's power, wanted to kill Sima Yi everywhere because he was at odds with Sima Yi, and Cao Shuang even sent assassins in order to get rid of Sima Yi, in this case, Sima Yi had to make a precaution. The struggle between you and me in politics eventually turned into a political upheaval.
In 249, Sima Yi took advantage of Cao Shuang's departure from beijing to worship Gao Pingling and suddenly took control of the whole of Luoyang, and Cao's relatives fell overnight, while Sima Yi completely took control of the Wei state.
After Cao Fang, the King of Qi, succeeded to the throne, Sima Yi endured Cao Shuang for eleven years, and he was always waiting for this last opportunity. The reason why Sima Yi had such an act can be said to be entirely due to the suspicion of Cao's relatives. As for why Cao Fang would allow such a thing to happen, first, because Cao Fang was young and had no ability to pro-government, and second, Sima Yi had already gained the heart of the imperial and wild warriors, and Cao Fang lost control of Sima Yi.