For the Shu Han regime in the Three Kingdoms period, there were two wars that determined the national fortunes of Shu Han, the two wars were the Battle of Hanzhong and the Battle of Yiling, and the place where the two wars took place was Hanzhong and Jingzhou, which happened to be the place that determined the fate of Shu Han, because according to Zhuge Liang's plan of "Longzhong Pair", Liu Bei's group occupied Jingyi Erzhou, so that it was possible to chase the deer in the Central Plains, and Hanzhong and Jingzhou were two important strategic places, so for the Shu Han regime, who was the "life gate" of Shu Han in Hanzhong and Jingzhou?
Simply put, whether hanzhong or Jingzhou is lost, for the Shu Han regime, it is a matter of life and death, but the meaning of the two is still different.
It can be said that Jingzhou determines the upper limit of Shu Han, and Hanzhong determines the lower limit of Shu Han.
Why?
In fact, this just reflects the importance of the geographical location of the two, open the map we can see that Jingzhou is located in the middle reaches of the Yangtze River, roughly the current two lakes area, in the Three Kingdoms period, the Jingzhou area was basically not affected by the war, and here is rich in products, whether from the geographical or material point of view, is a rare good place, since ancient times Xiangyang is a strategic place, because from Xiangyang to the north can directly threaten the Central Plains, this is also Guan Yu launched the Battle of Xiangfan, The reason why Cao Cao almost moved the capital.
And from Zhuge Liang's "Longzhong Pair" can also be seen that his strategy for Liu Bei is also to occupy Jingyi Erzhou, if the Northern Expedition, you can send troops from jingzhou and Yizhou two directions to the north, so that it is possible to have the possibility of chasing deer in the central plains, but the transportation between Jingzhou and Yizhou is inconvenient, mostly mountainous barriers, so in history Shu land in the war years can often be divided, for Liu Bei regime, it is difficult to establish effective communication and support between the two places, which is also an important reason why Guan Yu's defeat of Liu Bei failed to give immediate help. It is because the strategic position of Jingzhou is important, so Liu Bei will launch the Battle of Yiling in spite of the Qunchen, because Liu Bei understands that if He loses Jingzhou, then his grand blueprint for unifying the Central Plains will be directly cut off, and Shu Han will basically occupy Shu Land to protect himself, and even if Zhuge Liang is vigorously going north, it will not change the national conditions of Shu Han.
And Hanzhong belongs to the northern gate of the Shu Han regime, his north is the Qinling Mountains, the geographical location is extremely important, once Hanzhong is occupied by the locality, Shudi is equivalent to "the opening of the national gate", because of this, Liu Bei learned that Cao Cao destroyed Zhang Lu and occupied Hanzhong, decisively negotiated peace with Sun Quan, and then almost threw all his wealth to win the battle of Hanzhong, to know that Liu Bei was Zhang Fei Zhao Yun Huang Zhongfa Zheng these people all brought away, these show the importance of Hanzhong to Shu Han, it is precisely because of Hanzhong, Only then did it ensure that the Shu Han regime maintained its rule for more than forty years.
It can be said that Hanzhong decided to the lower limit, representing a corner of the Shu Han regime, Jingzhou represents the upper limit is to chase deer in the Central Plains, it is precisely because of the loss of Jingzhou, Shu Han can only retreat to Shu land, and lose Hanzhong, Liu Chan directly surrendered, Shu Han fell to the country.
In fact, from another direction, the Hanzhong region is conducive to defense, and the Jingzhou area is conducive to attack, Zhuge Liang's five northern expeditions out of Qishan, basically all of them are fruitless, which also shows the fact that Hanzhong is not conducive to the attack, and Jingzhou is the forward position of the attack, if the Shu Han regime did not lose Jingzhou, on the one hand, the Northern Expedition can attack in two ways, even if the Cao Wei regime defends, it does not dare to easily give up a direction, Zhuge Liang will not face Cao Wei's key defense again, if Eastern Wu re-joins in, It is indeed very likely that Zhuge Liang's original idea of reviving the Han Dynasty was realized.
Secondly, the north of Jingzhou is the core area of the Cao Wei regime, whether it is Luoyang or Xuchang, it is very close to Jingzhou, which is also the most effective way to directly threaten Cao Wei, so that Cao Wei has to arrange heavy defense, if the Northern Expedition transports grain and grass, it is far easier than from Hanzhong, so that there will be no problem of poor grain and grass in the northern expedition of Zhuge Liang, so although Hanzhong and Jingzhou are very important to Shu Han, but jingzhou is lost, at most it means that Shu Han has lost the hope of unifying the world. However, the loss of Hanzhong represents the fall of the country, because crossing Hanzhong is shudi, and the soldiers can reach the city of Chengdu, is this not the way for Deng Ai to destroy Shu?