In the first ten years (249), Sima Yi launched the "Gaopingling Rebellion" to kill Cao Shuang, and Cao Wei's power fell into the hands of Sima Shi. But what is less known is that Jiang Ji, an old minister of Cao Wei and then a lieutenant, played an important role in the "Gaopingling Change". It can be said that without the support of Jiang Ji, the Sima Yi clan may not be able to succeed in the coup. Jiang Ji's assurances were also one of the main reasons for Cao Shuang's voluntary surrender.
According to the Chronicle of the Three Kingdoms, Wei Shu, Cheng Guo Dong, Liu Jiang, and Liu Biography, Jiang Ji used a letter in Hefei in his early years to scare Sun Quan away, and won the elegant title of "Jiang Yifeng", and was a loyal subject of Cao Wei who withstood the test. The three emperors of Cao Cao, Cao Pi, and Cao Rui trusted Jiang Ji very much, and even handed over the forbidden army in Luoyang to Jiang Ji's command. So why did Jiang Ji support Sima Yi in the "Gaopingling Change"?
Because the Western Jin Dynasty replaced Cao Wei, many "hindsight Zhuge Liang" went to see Sima Yi with a "God perspective", for example, a director and screenwriter who should apologize to the people of the whole country made Sima Yi into a face-like character full of anti-bones. But in fact, Sima Yi did not show anti-bone until the last few years of his life, and had always shown himself as a loyal minister of Cao Wei before, and Jiang Ji also saw it this way.
More importantly, Cao Shuang really did too badly. After Cao Rui's death, Cao Shuang successively took away Sima Yi's military power and Jiang Ji's command of the forbidden army by means of a bright ascension and a secret surrender, turning the emperor's forbidden army into his own private army. However, Cao Shuang implemented many unpopular policies after taking power, but Jiang Ji's repeated advices had no effect. In public and private, Jiang Ji would hate Cao Shuang's party.
In the first five years (244), Cao Shuang's attack on Ji Han suffered a crushing defeat and his prestige plummeted. In order to save his prestige, the great general Cao Shuang decided to treat himself like the emperor, and took the emperor's utensils and honors for himself, and his life became more and more absurd, even Cao Rui's concubines did not spare. Moreover, as Cao Fang grew older, Cao Shuang showed no sign of returning to politics at all.
In the first eight years (247), Cao Shuang put Empress Guo under house arrest. It should be known that Empress Guo was Cao Rui's empress dowager and had a high political status, and later Sima Shi and Sima Zhao both treated Empress Guo with courtesy on the surface. Importantly, Cao Fang opposed empress dowager Guo's house arrest, but Cao Shuang humiliated Cao Fang to her face. By this time, Cao Shuang's image had changed to "named Wei Xiang, but actually a Wei thief".
Because of this, Jiang Ji, who was loyal to Cao Wei, secretly planned with Sima Yi to eliminate Cao Shuang's party. It can be said that Jiang Ji's mentality at this time was a bit similar to that of the Eastern Wu ministers who later supported Ding Feng in eliminating Sun Qi, and wanted to eliminate the traitors for Cao Wei by supporting the loyal old minister Sima Yi. Unfortunately, Sima Yi was not a loyal vassal of Cao Wei.