The great cause of Shu Han's northern expedition to the Central Plains and the revival of the Han Dynasty ended with Zhuge Liang's death in the army. Then why did Zhuge Liang do it knowing that he could not do it? After Liu Wei, the queen of the Three Kingdoms Shu Kingdom, ascended the throne, Zhuge Liang took charge of Shu, and repeatedly went to the Northern Expedition, but failed to return. Eventually, he was exhausted and lost his way, which often made people sigh! At that time, Shu was weak and easy to defend but difficult to attack. Why did the talented Zhuge disregard the reality, overreached himself and insisted on the Northern Expedition? Later historians have different opinions.

The formation of the three kingdoms and the independence of Shu and Han in Yizhou had a lot to do with the post-war population loss in the Central Plains at that time. At that time, the minister said that the population of Wei added up to the population of a county in the Han Dynasty. Although this is an exaggeration, it shows that the economy and society in the Central Plains have been seriously damaged. At the same time, Yizhou, Jingzhou and Yangzhou are relatively free from unrest because of Liu Zhang, Liu Biao and Sun Ce. Even the refugees from the north have given the local area opportunities for further development. Sun Ce side, Zhang Zhao himself is a northerner. Liu was in Zhang's place, and the reason why he was able to hold steady Yizhou was largely due to the Dongzhou soldiers composed of Jingzhou refugees. Once the north goes through a period of peace, the economy gradually recovers and the whole south is United, there is no way to compete with the north. This situation remained the same in the Sui Dynasty, and gradually changed after the Tang Dynasty. To put it simply, for Sun Liu, the separation of the South is only temporary.

Zhuge Liang is a visionary strategist. He knows that Yizhou, a small place, has very limited development space. However, there is still great room for development in the Central Plains occupied by Wei. Once the productivity of the Central Plains is restored, the strength contrast between Wei, Shu and Wu will rapidly widen, and national reunification is only a matter of time.

Therefore, Zhuge Liang insisted on the Northern Expedition when his strength was obviously inferior to that of Wei, with the aim of constantly harassing Wei strategically and making it unable to develop peacefully. If the war goes well, we can further compete for the Central Plains. If the war goes badly, we can also take advantage of the natural disasters in Sichuan, and at the same time achieve the strategic goal of consuming Wei's national strength and slowing down the economic recovery of the Central Plains.

To sum up, Zhuge Liang's Northern Expedition was mainly aimed at forcing Wei's conscription to stay away from the border, consuming national strength and causing potential social unrest, thus slowing down the speed of economic recovery in the north.

Once there is an opportunity, March into Guanzhong and compete for the Central Plains. If there is no chance, we will preserve our national strength and consolidate our control over Shu Han. Therefore, Zhuge Liang's northern expedition is generally based on safety, and it is very good to earn an army and be a member of Wei State. Zhuge Liang has done this very well.