At the beginning of the Battle of Yiling, Liu Bei's army was very strong, and Sun Quan felt a lot of pressure, and he whispered to Cao Pi in various ways, calling him a tribute, and Cao Pi's request was no matter what it was, he agreed to it. Among them, it included promising to send his son to Cao Pi as a hostage. However, after the Battle of Yiling, Sun Quan defeated Liu Bei, Sun Quan's face changed, the proton was not sent, and the previous request was also pushed forward. Therefore, Cao Pi was determined to take revenge on Sun Quan.
At this time, Cao Wei and Sun Quan faced each other in the directions of Jingzhou and Jianghuai, respectively, while Liu Bei's side only faced each other in the direction of Hanzhong. Sun Quan faced pressure from both Liu Bei and Cao Wei in the direction of Jingzhou. After the Battle of Yiling, Liu Bei collected the remnants of his troops and retreated to the White Emperor's City, on the one hand, to resist the pursuing Wu army, on the other hand, he was also waiting for the opportunity to send troops to avenge.
Therefore, hearing the news that Cao Pi had sent troops, Liu Bei also wrote a letter to tease Lu Xun, saying that if he also learned from Sun Quan, at this time, he would take the initiative to cooperate with Cao Wei and attack Sun Quan, what would be the result? Lu Xun wrote back saying that he would not accept the flirtation, saying that you had just experienced the defeat of Yiling, so don't brag.
The Chronicle of the Three Kingdoms lu xun is quoted as follows:
Liu Bei heard that the Wei army was out of the woods, and the book and Sun Yun said: "The thief is now in Jiangling, I will restore the east, and the general will say that he can not do it?" Sun replied: "But the fear of the army is newly broken, the creation has not been restored, the beginning of the request for relatives, and should make up for themselves, and there is no time for the ears of the soldiers." If you do not calculate, if you want to overthrow, those who have been sent far away will have no way to escape. ”
At this time, Liu Bei once again showed his courage of "Han thieves are not separated" that he should have as an orthodox han family, and when Cao Pi attacked Sun Quan, he did not cooperate with Cao Pi and attack Sun Quan, but instead defended himself and watched from the sidelines.
If Cao Pi led hundreds of thousands of troops to conquer Shu at this time, Wei Yanma chao and other northern troops would definitely rely on the terrain to resist desperately; the eastern front of Shu Han had collapsed, the south would have to oppose, Lu Xun would take advantage of the situation to advance westward, Wu could get Shuzhong and Nanzhong, and whether Cao Wei could win Hanzhong was still unknown. In this way, the State of Wu ate the State of Shu, and Cao Wei made a wedding dress for Eastern Wu, and one strong against two weak became two strong opponents.
Moreover, at this time, if Liu Bei asked Sun Quan for peace, sun Quan also agreed, Cao Wei's hundreds of thousands of troops were in the west, and Eastern Wu would definitely send troops in the opposite direction of Xiangfan, Hefei, and Guangling, and cao Wei's defenders could hold it? As long as one thing is lost, the back is all a horse flat river.
Moreover, Hanzhong itself was easy to defend and difficult to attack, and the supply line was long, and the general Wei garrison was basically not easy to fight. Once the losses were large, Sun Liu was not allowed to jointly backstab. From the perspective of positive history, it seems that there was a plague in Cao Wei at that time, and the ethnic minorities in the north also engaged in rebellion, and Cao Pi was busy dealing with internal and external troubles.