In Sima Yi's view, as long as we can persist, the Shu-Han army will retreat because of the consumption of grain and grass. In other words, Sima Yi's attitude is not seeking success, but seeking nothing. Of course, this also reflects Zhuge Liang's oppression of Cao Wei. As we all know, after the pattern of the three countries was fully formed, Shu Han became the weakest party among the three countries. Shu Han and Cao Wei have multiple gaps in military strength and population. Therefore, for Cao Wei, who has a large number of troops, it can take the initiative to attack, not passively defend. In June of 23 1 year, Zhuge Liang, the prime minister of Shu, found that the grain and grass could not meet his own needs and received an imperial edict from Liu Chan, ordering the Northern Expeditionary Army to retreat. Zhuge Liang had to lead the army back. It is worth noting that in the face of the retreating Shu-Han army, Sima Yi and Zhuge Liang once again disagreed. Zhang Ying thought that the poor enemy should not be pursued, but Sima Yi insisted that Zhang Ying pursue the Shu army. As a result, Zhang Ying's right knee was ambushed and shot by the Han army in a highland on the wooden door road, and eventually he died. It can be seen that Zhang Ying, a famous Cao Wei soldier, was successfully killed for the Shu army, which had left for lack of food. However, the author thinks that although Zhang Ying was a famous soldier at that time, on the whole, Zhuge Liang's fourth Northern Expedition was futile, because he did not attack the city and plunder the land, nor did he seriously damage Cao Wei.
Finally, more importantly, in the eyes of some historians, Zhuge Liang got rid of Zhang Ying and indirectly helped Sima Yi. If Zhang Ying had not been killed, veterans loyal to Cao Wei would undoubtedly become an important obstacle for Sima Yi to usurp power. The change of Gaoping Mausoleum was due to the lack of a star loyal to Cao Wei like Zhang Ying, and Sima Yi was lucky enough to successfully seize the Cao Wei regime. For Zhuge Liang, his fourth northern expedition did not return to the Central Plains, which was obviously directly related to Li Yan. During Zhuge Liang's fourth northern expedition to the Central Plains, Minister Li Yan was responsible for transporting food, forage and other materials. At that time, Li Yan was afraid of poor transportation of grain and grass, so he sent Ma Zhong and Fancheng to preach and asked Zhuge Liang to retreat. After Zhuge Liang came back, Li Yan asked him: Why did you come back with enough food? ? In other words, Li Yan not only shirked responsibility, but also wanted to frame Zhuge Liang, the prime minister of Shu Han.
On the other hand, Yan Li also wrote a letter to Queen Liu Chan, deceiving Liu Chan that it was a strategy and trying to shirk her responsibility for Censhu. This not only angered Zhuge Liang, the prime minister of Shu Han, but also angered the soldiers of Wei Yan, Wu Yi and Wang Ping. Zhuge Liang directly showed Li Yan's previous handwriting for the first time, which was obviously inconsistent. Li Yan has nothing to say. Then Zhuge Liang and officials jointly played the role of Queen Liu Chan and abolished Li Yan's civilian status. Li Yan finally died in 234 AD. As Liu Bei's ancient expansion minister, Li Yan not only failed to help the Han Dynasty, but also destroyed Zhuge Liang's fourth Northern Expedition, so the final result is naturally not worth regretting.