The most famous thing in Cao Cao's life was obviously "holding the Son of Heaven hostage to order the princes", he relied on his strong military strength, gained actual power, so that the emperor had to obey his orders, although his Wei state was nominally only a fief given by the emperor, but in fact it was already a solid princely state, and Cao Cao himself was also the founder and founder of the Cao Wei regime.
The two important reasons why Cao Cao did not claim the title of emperor were, on the one hand, his complex as a courtier of the Han Dynasty, and on the other hand, he had not yet unified the world. In fact, as early as when he was named "King of Wei", Cao Cao had thought of calling himself emperor, but under the persuasion of the counselors, he finally decided to do so after successfully unifying the world, but he never unified the world, and naturally did not wait for the day when he was called emperor.
However, Cao Cao obviously regarded the world as his own pocket, which can be seen from his evaluation of Sima Yi: this is not a human subject, he will mess with my family affairs one day. Sima Yi is a courtier, that is to say, he is the one who wants to be the emperor and get the world, and he will definitely come to disturb the affairs of our family in the future, to get the world! Cao Cao already regarded the affairs of the world as his own family affair.
Interestingly, although Cao Cao had such an evaluation of Sima Yi, in the end he did not kill Sima Yi, but instead killed a prodigy known for his talents, Zhou Buxi. Zhou Bu was only sixteen years old when he died, and Cao Pi once suggested to Cao Cao not to kill, but Cao Cao said, "This is not something that Ru can control", so he directly killed Zhou Buxi, which shows that his defensive mentality is very strong.
So why didn't he kill Sima Yi? The reason was probably that Sima Yi was very honest at that time and was still very useful to Cao Cao, so Cao Cao did not kill him at that time, but thought that he would have the right time to kill him later, but later he forgot about this matter, and finally there was the "Sima Dai Cao" thing, Sima Yi became a powerful minister of Cao Wei, and his descendant Sima Yan completely replaced Cao Wei and established the Jin Dynasty.
Judging from the final outcome of Cao Wei being replaced by the Sima family, it was obviously a mistake for Cao Cao not to kill Sima Yi, and Sima Yi also made the same mistake, he also forgot to kill a person who should have been killed by him, that is, Huan Fan's son Huan Kai.
The key event in Sima Yi's seizure of cao wei's power was the "Gaopingling Change", he led an army to control the whole of Kyoto and seize the military power of the Cao family's clan, but if cao Shuang, the leading figure of the Cao family, listened to Huan Fan's opinion, then Sima Yi would not have been able to succeed in the coup, but Cao Shuang naively believed that as long as he surrendered, he could become a rich man in peace and stability, so he did not listen to Huan Fan's opinion but chose to surrender, and eventually the whole clan was destroyed.
Sima Yi, after learning of Huan Fan's suggestion to Cao Shuang, was also in a cold sweat, believing that this was a serious problem in his heart, and immediately ordered the killing of Huan Fan's three clans, but Huan Fan's son Huan Kai ran out in advance and lived in anonymity, and Sima Yi did not send anyone to pursue and kill, and as a result, Huan Wen's descendants appeared Huan Wen.
Huan Wen shined in the Jin Dynasty and became a powerful vassal in the actual sense, and repeatedly tried to depose the emperor but ultimately did not implement it, but his Huan Xuan eventually deposed the Jin Emperor and created Huan Chu, destroying the Jin Dynasty. The two dynasties of Cao Wei and Sima Jin, because of the difference in the founder's thoughts, eventually achieved extremely similar endings, which made posterity sigh with emotion.