At the end of the Eastern Han Dynasty, Zhang Lu, who was a combination of politics and religion, was in charge of Hanzhong. Five barrels of rice? The rule of socialism? Thirty years of Bahan? However, after Cao Cao pacified Guanzhong, the soldiers pointed directly at Hanzhong and led the army to attack Hanzhong. After half a year's fighting, he finally landed in Zhang Lu and took Hanzhong into his pocket, but later he failed in the battle with Liu Bei and transferred the population of Hanzhong to Liu Bei.
Then Hanzhong is a battleground for military strategists. Why did Cao Cao say that? What a pity to eat tasteless and abandon it? What's more, tasteless food can be understood as Cao Cao's appropriation of Zhang Lu's property before he occupied Hanzhong. But the mountain is high and the road is far, which is really not the key business area for Cao Cao, who unified the north. Unfortunately, Hanzhong is very important to Shu Han and is the gateway to its external expansion. Cao Cao didn't want to take advantage of Liu Bei.
However, Hanzhong is of great military significance to Cao Wei, who has occupied the Central Plains, but it is far from a place of life and death. If Yizhou can be occupied in one fell swoop, then Hanzhong is a must. If you have no strength for the time being and just engage in strategic stalemate with Yizhou, it is good to master Hanzhong, but if the price is too high, will Hanzhong become what Cao Cao said? Chicken ribs? .
Hanzhong can be defended with only a small amount of troops with the help of favorable terrain because of the limitation of terrain; But for Cao Cao, it is necessary to station troops. Cao Cao attacked Zhang Lu, and the army has traveled thousands of miles since Wudu Mountain, with ups and downs and obstacles, and the soldiers worked hard? At that time, Xia and Zhang He's tens of thousands of troops could not resist Liu Bei's attack. When Cao Cao's army came, the logistics of the army needed to be transported from Guanzhong and even the mainland. After a long journey, it has brought a heavy burden to the country. However, the Central Plains has just experienced war, and the people are poor and rich, and Sun Quan is eyeing up in the East. Cao Cao is really not allowed to spend more energy, material resources and manpower on Hanzhong defense. Finally, he put his own? Chicken ribs? Throw it to Shu Han and shrink his defense to Guanzhong.
At the same time, Cao Cao moved all the people in Hanzhong to Guanzhong, turning Hanzhong into an empty wilderness, thus throwing the problem of dangerous roads in Hanzhong to Shu Han, which led to Zhuge Liang's failure to get supplies along the way during the Northern Expedition. I had to retreat several times because of lack of food and grass, and there was no breakthrough in the last few decades. Cao Cao, on the other hand, can cultivate self-cultivation and restore and enhance national strength by defending and avoiding war. This also proves that Cao Cao's judgment on Hanzhong is correct.