Cao Wei's second emperor Cao Rui, having…
244 CE
Cao Wei's second emperor Cao Rui, having grown ill around the new year of 239, had resolved to pass the throne to his nephew Cao Fang, who he had adopted at a young age and made Prince of Qi in 235.
Cao Rui had initially wanted to entrust Cao Fang to his uncle Cao Yu, to serve as the lead regent, along with Xiahou Xian, Cao Shuang, Cao Zhao, and Qin Lang.
However, his trusted officials Liu Fang and Sun Zi were unfriendly with Xiahou Xian and Cao Zhao and were apprehensive about their becoming regents, and managed to persuade him to make Cao Shuang (with whom they are friendly) and Sima Yi (who was at that time with his troops at Ji (in modern Xinxiang, Henan) regents instead.
Cao Yu, Cao Zhao, and Qin Lang had been excluded from the regency.
As a result, Cao Shuang had risen to power but is clearly inadequate for the important job assigned to him.
When Cao Rui asked him if could do it, Cao Shuang was so nervous that he could not even say a word to answer and finally, it was Sima Yi who had answered for him, promising Cao Rui that they would do their best and Cao Rui would have nothing to worry about.
Despite his inability, Cao Shuang and his brothers, Cao Xi and Cao Xun wield great power in Cao Wei, and he is often at conflict with Sima Yi, who has greater influence and support.
In 243, Sima Yi's position had been further strengthened by another successful deployment: Zhuge Ke of Eastern Wu was constantly sending agents to Shouchun to prepare an invasion, so Sima Yi had led Cao Wei forces to Shu county of Lujiang Shire, near the border.
Hearing the news, Sun Quan had immediately ordered Zhuge Ke to withdraw to Chaisang County, Yuzhang Shire.
Sima Yi's popularity and influence had instantly multiplied as he was lauded as being able to scare away the enemy, numbering over a hundred thousand, without a fight and thus secure the border and save the city from certain attack.
Alarmed, Cao Shuang uses his authority, greater than that of Sima Yi, to persuade the emperor, Cao Fang, as a reward, to promote Sima Yi to the rank of Grand Tutor, which actually means that Sima is in an honorary position and is left without any real authority in military affairs.
Cao Shuang, desperate for a victory to boost his own fame, had selected Shu Han as his target.
Despite facing strong opposition in the Wei court, Cao Shuang believed that the campaign was viable, especially when the Shu commander, Jiang Wan, withdrew his main force from Hanzhong to Fu County in October 243.
Cao Shuang and his protégés have concluded that, with numerical superiority, their army can easily conquer Hanzhong before Shu reinforcements arrive.
Even if they fail to completely eliminate Shu, the fall of Hanzhong would be sufficient to increase Cao Shuang's fame and influence in the Wei court.
Leading an army numbering more than sixty thousand, Cao Shuang invades Shu Han in March, 244.
However, two months later, he is soundly defeated by Wang Ping and Fei Yi in the Battle of Xingshi, and is barely able to escape back to Guanzhong with his own life.
The most devastating result, however, is that Cao Shuang has lost more than one hundred and twenty thousand troops, or fifteen percent of the total armed troops of Cao Wei's eight hundred thousand army, a serious blow from which Cao Wei cannot recover.
Furthermore, most of the lost troops belonged to Cao Wei’s best units.
Cao Shuang's popularity and influence drops to a new low, while at the same time, Sima Yi's popularity and influence further increases, as it is known that he had opposed the campaign from the start.