Wei Yan has been guarding Hanzhong for 40 years. Why can't Jiang Wei keep it for 30 days?

First of all, it is extremely important to know the location of Hanzhong. It acts as a gateway. Liu Bei knew the importance of Hanzhong at that time, so he let Wei Yan personally guard it after capturing Hanzhong. It has been calm, and Wei Yan's guarding Hanzhong is also dead. ?

But all this calm changed after Zhuge Liang's death. After Zhuge Liang died of illness, Wei Yan was killed for rebellion. At this time, there were few generals left in Shu Han, and Jiang Wei became one of the most outstanding figures in Shu Han army at this time. ?

Because Jiang Wei was promoted by Zhuge Liang, many of his strategic thoughts continued at that time. For example, like Zhuge Liang, he insisted on the Northern Expedition and won and lost many times in the Northern Expedition. However, repeated attacks like this have actually not made substantial progress, but have consumed a lot of military materials. ?

Wei Yan's strategy of defending Hanzhong for many years is actually one, and that is defense. This is why Hanzhong is impregnable and no one can conquer it. However, Jiang Wei is a very enterprising person. He felt that Wei Yan was blindly guarding Hanzhong, but it didn't work. ?

So Jiang Wei started a new strategy, but lost Hanzhong. In fact, at that time, because Jiang Wei's troops were actually very few, the transfer right of Hanzhong defenders was not in Jiang Wei's hands. After the fall of Yang 'an Pass, Liu Chan did not send reinforcements to attack and defend Yang 'an Pass, which gave Wei Jun a chance to enter Shu. ? Hanzhong fell because Yang Anguan fell. It was also because Jiang Wei boldly changed Wei Yan's strategic thinking that he came up. He was so radical that he lost the game. ?