Why did Sima Yi cut down Shu instead of Wu back then

First, from the perspective of legitimacy, the Shu Han State claimed to be the orthodox Han dynasty and competed with Cao Wei for the legitimacy of the regime. Zhuge Liang said in "The Later Teacher's Table", "The Han and the thief do not stand together, and the king is not partial", if you don't beat him, he will slow down, but he will beat you, and this is the reason for several Northern Expeditions.

Second, from the perspective of the comparison of national strength, the "General Examination of Literature" says: Wei Wu is based on the Central Plains, Liu Bei cuts Bashu, Sun Quan has all the land of Jiangdong, the Three Kingdoms are established, the war is endless, the Wei family is 663423, and the mouth is 4432881; In the first year of Zhangwu of Han Zhaolie, there were 200,000 households, 900,000 men and women; At the time of Shu's death (263), there were 280,000 households, 940,000 mouths, 102,000 armored soldiers, and 40,000 officials; In the third year of Wu Chiwu (240 years), there were 520,000 households, 2.3 million men and women, and when Wu died (280 years), there were 530,000 households, 32,000 officials, 230,000 soldiers, and 2.3 million men and women.

It can be seen that Cao Wei has the largest population, followed by Sun Wu, and Shu Han has the least. In the era of cold weapons, everyone's weapons level is about the same, and basically there are more people, and there are fewer people in Shu and Han, and there are relatively few soldiers. Shu Han made several northern expeditions, with a large consumption of troops and a lack of commanders, so Shu Han's comprehensive national strength was weaker and easier to win than Eastern Wu.

Eastern Wu has the Yangtze River natural danger, and the northern soldiers of Wei are not used to fighting in the south, and there is a lesson from the red cliff before, so the Shu Han strategy is preferred.

Moreover, Shu Han lives in the upper reaches of the Yangtze River, and it is naturally easy to take Sun Wu from the upstream downstream.

Because the state of Wu is already very chaotic, and the state of Shu is slowly recovering its national strength, the longer it takes to eliminate the state of Shu, the more difficult it is to eliminate the state of Shu, and the easier it is to eliminate the state of Wu, so destroy Shu first and then destroy Wu.

Shu had two northern expeditions, the consumption of troops was large, and there was a lack of talent among commanders, Zhuge Liang was not an excellent military strategist, and he died later, and Adou was not a Ming monarch, so Shu's comprehensive national strength was weaker and easier to take than Eastern Wu. Eastern Wu had the Yangtze River natural danger, and the northern soldiers of Wei were not used to fighting in the south, so Shu gave priority to attacking.

Because it is easier to cut down Shu, first hit the easy ones, and then hit the difficult ones.

Zhuge Liang led tens of thousands of troops to leave Xiegukou and sent envoys to Eastern Wu, hoping that Sun Quan would attack Wei at the same time. This was Zhuge Liang's fifth Northern Expedition to the Central Plains, and it was also his last attack on Cao Wei. Sima Yi thought:"If you are a brave man, you should walk east along the mountain road.

If you climb Wujoyuan to the west, there will be nothing to do"。Therefore, he led the Wei army to establish a camp in the last battle. He wanted to consume the food of the Shu army again in a protracted war, so he ordered the Han army to retreat on its own.

In August of the same year, Zhuge Liang fell ill due to overwork, and his condition became more and more serious. When the news of Zhuge Liang's serious illness reached Chengdu, Liu Chan sent Li Fu to visit Zhuge Liang and ask him about the future of Shu Han.

<> Zhuge Liang did not let Wei Yan participate in the deployment, but let Yang Yi and Fei Yi lead the team to retreat. Wei Yan and Jiang Wei were responsible for terminating the empress, which led to a fight between Wei Yan and Yang Yi. It didn't take long for Zhuge Liang to die in the barracks.

However, Yang Yi and Jiang Wei followed Zhuge Liang's deathbed plan to keep order in their troops and retreat calmly. Sima Yi thought that Zhuge Liang had fallen, and led his troops to pursue. Jiang Wei beat the drum and passed the flowers, forming an offensive.

Sima Yi did not dare to attack, so the Shu army retreated calmly and entered the valley. So, here comes the problem. After Zhuge Liang's death, Sima Yi wanted to take the opportunity to attack Shu.

In the later Wei period, the power of the Sima family went to the opposite side, and Cao Cao's descendants became puppets. After Sima Yi launched the Gaopingling Rebellion, Cao Cao's descendants became inferior. In Cao Cao's time, Sima Yi knew how to forbear.

But after the death of Cao Rong, Sima Yi's ambition gradually came out. Since then, Sima Yi has stopped being patient. Although Cao Shuang is a descendant of Cao Cao, his means are very poor and he can lead troops to fight.

In the early days of Cao Ei's administration, Sima Yi was already full of ambitions, but at that time Sima Yi was not Cao Ei's opponent. At the same time, under the circumstances of the time, Cao Wei did not allow Sima Yi to carry out a coup d'état. After Cao Rong's death, after the little emperor Cao Fang succeeded to the throne, the political struggle between the Cao family and the Sima family became more and more intense.

Because there was a man named Sima Zhao.

Because the strength of Shu at this time was not so strong, many capable generals had passed away, and the emperor at this time was not very loved.

This is because the national strength of Shu is weak and congenitally insufficient, and it cannot compete with Cao Wei, who occupies the rich land of the Central Plains.

Because after Sima Yi's death, the national strength of Wei is getting stronger and stronger, while the national strength of Shu is indeed getting weaker and weaker. Moreover, the Wei State can be said to be full of talents, while Shu Han is short of talents. And the anti-war voice within Shu Han was very high.

As soon as Zhuge Liang dies, Shu will die, is it necessary to work the people and lose money? At this time, it is important to usurp the master!

That's because Sima Yi also died after Zhuge Liang's death.

Sima Yi has never attacked Shu, and has been sent to defend and recover lost territories, and Wei is mainly fighting with Wu, and the troops are also there.

Because Sima Yi was worried that the destruction of Shu would lead to his high merit and shock the master, and he would be liquidated, after all, his power at that time was not big enough, and it was difficult to protect himself, so he did not dare to cut down Shu.

Because Sima Yi felt that no one could compete with him, he lost his desire to crusade against Shu.

Because Sima Yi was suspicious at that time, he could only remain silent in order to protect himself.