Sima Yi was recruited by Cao Cao at the age of 30. Later, in Battle of Red Cliffs, Sima Yi did not participate in several wars. In fact, it is not because of being young, mainly because when Cao Cao went to recruit Sima Yi for the first time 1 seven years ago, Sima Yi was only 23 years old. Cao Cao heard that Sima Yi was very talented and went to recruit him. At that time, Sima Yi pretended to be ill and didn't want to go out.
Therefore, Sima Yi was not buried, but didn't want to be sharp-edged. If he wanted to make achievements, he would have gone to Cao Cao when he was called up for the first time 1 time. At that time, he was still an ordinary warlord. Sima Yi has always been a cautious man. He is very good at waiting, so before the change of Gao Pingling, he even pretended to be ill for two years, in order to wait for the best opportunity and paralyze Cao Shuang.
When Cao Cao called him, he didn't go, just watching the situation. He waited until Yuan Shao's power was destroyed before he defected to Cao Cao. And until Cao Cao died of illness, he didn't do much for him. He just made some suggestions, which were positive, so there was no chance of promotion at first. Cao Cao himself was very suspicious of Sima Yi, so when Cao Cao died, he let his son kill Sima Yi. At that time, Sima Yi was saved from killing because he pretended to be ill. Sima Yi's ultimate goal was nothing more than the rights owned by the Cao family.