After Liu Bei's death, Zhuge Liang was honored as his father by the empress dowager Liu Chan, and in order to repay Liu Bei's kindness and fulfill his last wish to restore the Han Dynasty, Zhuge Liang went out on several occasions to go on the Northern Expedition. During this period, the most important opponent he encountered was Sima Yi. In the Romance of the Three Kingdoms, Zhuge Liang's wisdom was always half a point higher than Sima Yi's, so when the two sides fought, Sima Yi was often the losing side. Even with only more than 2,000 old, weak and disabled soldiers in the Western City, he was still scared away by Zhuge Liang's empty city plan.
However, for various reasons, the first few Northern Expeditions were unsuccessful, and in 234 AD, after making full preparations, Zhuge Liang sent his last army out of Qishan and northern expeditions to the Central Plains, and his opponent was still Sima Yi. In order to completely eliminate Sima Yi, Zhuge Liang set up an ambush in the upper valley and buried many fire-setting objects. Wei Yan was then sent to defeat and introduce Sima Yi's father and son into the Upper Valley. After Sima Yi's plan, Zhuge Liang once again used his best tricks to put a fire in the upper valley, and Sima Yi's father and son were trapped in the fire and were about to be burned to death.
Unexpectedly, at this time, a sudden heavy rain fell from the sky, which instantly extinguished the fire. Zhuge Liang calculated everything, but he could not think that it would rain in the sky, and there were not many soldiers guarding the valley mouth, so Sima Yi's father and son were lucky to get back a life. After escaping from danger, the terrified Sima Yi suddenly looked up to the sky and laughed, and Sima Zhao and Sima Shi's brothers were confused at that time, and thought that Sima Yi had a mental problem. What they didn't know was that Sima Yi suddenly opened his mind after this fire and found a way to defeat Zhuge Liang.
In the Romance of the Three Kingdoms, Zhuge Liang was best at fighting sports warfare, and his brilliant ideas could only exert their power in sports warfare, such as ambushes, such as fire attacks. If the other party does not play with you in the opposition, but just insists on it, Zhuge Liang's tricks will all lose their effect. Throughout Zhuge Liang's life, he has few brilliant achievements in tackling tough problems. For example, during the Second Northern Expedition, a small Chen Cang, he fought for more than 20 days and failed to capture it, while the defenders only had more than a thousand people.
It can be seen from this that Zhuge Liang's military ability is flawed to a certain extent, and he is good at mobile warfare rather than attacking strong points. Before the ambush in the upper valley, Sima Yi was not very convinced of Zhuge Liang, and always wanted to confront Zhuge Liang in the field. However, after the Battle of Shanggu Valley, he thoroughly realized that he was not Zhuge Liang's opponent at all in the field battle, and the only way was to hold out, and the fragile national strength of the Shu state could not withstand long-term consumption, and he could completely consume the Shu army in peace and stability. After that, Sima Yi resolutely implemented this approach, and no matter how humiliated the other side, it was a closed door. Zhuge Liang was helpless in the face of this situation, worried and overworked, and soon after he died of illness in Wuzhangyuan, Sima Yi finally laughed to the end with an disgraceful means in the duel with Zhuge Liang.