Delimitation of Xiangjiang River: Why did Liu Bei choose to withdraw his troops and give Jingzhou two counties to Sun Quan?

There is a folk allegorical saying: "Liu Bei borrowed Jingzhou-if he borrowed it, he would not be able to pay it back", which gives people the impression that Liu Bei is cheating and not paying it back. People mistakenly think that he borrowed the whole Jingzhou, but this is not the case. At the end of the Eastern Han Dynasty, Liu Biao occupied Jingzhou. At that time, Jingzhou was located in the middle reaches of the Yangtze River, with rich resources and a large population. Moreover, the geographical location of Jingzhou is very important, and it can enter Yizhou in the west and Jiangdong in the east. There are seven counties in Jingzhou (Nanyang County, Nanjun County, Jiangxia County, Changsha County, Lingling County, Wuling County and Guiyang County). After Battle of Red Cliffs, Jingzhou was divided between Wei, Shu and Wu. Among them, Cao Cao was defeated, but he still guarded Nanyang and Xiangyang counties in the north, while Liu Bei led the army to capture the four counties in Jingnan.

After Zhou Yu's death, Lu Su of Soochow persuaded Sun Quan to "lend" a part of Jingzhou occupied by Soochow to Liu Bei, so that Liu Bei could gain a firm foothold and fight against Cao Cao with Soochow. Therefore, Liu Bei once occupied the land of five counties in Jingzhou because of the south county borrowed by Soochow, and became the biggest winner. Of course, after Liu Bei captured Yizhou, Sun Quan naturally sent someone to beg for Jingzhou. On this basis, Sun and Liu demarcated the Xiangjiang River. Then, the question comes, Xiangjiang demarcation: Liu Bei has given up two counties in Jingzhou, so why did Sun Quan attack Jingzhou?

First of all, for Liu Bei, "borrowing Jingzhou" is actually just borrowing the south county of Jingzhou. Later, Liu Bei got Yizhou, and Sun Quan sent someone to ask for Jingzhou. The relationship between the two sides was tense and tense. When Cao Cao entered Hanzhong, Liu Bei was worried about losing Yizhou and sent messengers to make peace with Sun Quan, who was also worried about not winning. So the two families re-divided Jingzhou, with Xiangshui as the boundary: the east of Changsha, Jiangxia and Guiyang counties belonged to Sun Quan; Nanjun, Lingling and Wuling belong to Liu Bei, and Liu Bei and Sun Quan each occupy three counties. In this way, Liu Bei not only "returned" a county, but also gave up a county. So in my opinion, Liu Bei had already made concessions when he demarcated Xiangjiang River. At first, he only lent you Sun Quan a south county, and now he gives you two counties, Changsha County and Guiyang County.

So in terms of quantity, Liu Bei didn't let Sun Quan suffer. However, for Sun Quan, it seems that he is not satisfied. Guan Yu launched the battle of Xiangfan, and Sun Quan chose to betray the Sun-Liu alliance, sneak attack Jingzhou, and even slay Guan Yu and his son. In this regard, in my opinion, after the demarcation of Xiangjiang River, Liu Bei had ceded two counties in Jingzhou, but Sun Quan chose to sneak attack Jingzhou. The reasons are mainly divided into the following points. On the one hand, for Liu Bei, although Changsha County and Guiyang County in Jingzhou were ceded to Sun Quan, the Nanjun borrowed before was not actually returned to Sun Quan.

Furthermore, although Changsha County and Guiyang County have a larger scope, the geographical location of Nanjun County is more important. As for Nanjun, located in the middle reaches of the Yangtze River, it can directly threaten Wu Dong in the middle and lower reaches of the Yangtze River. For example, Jianye, the capital of Wu Dong, which is now Nanjing, is located in the lower reaches of Nanjun, which means that the navy division built by Guan Yu has every opportunity to directly attack the hinterland of Wu Dong in the lower reaches. To some extent, Guan Yu, who owns Nanjun County, is no less threatening to Wu Dong than Cao Wei, who is stationed in Huainan. Of course, from Liu Bei's point of view, there are also reasons why he does not want Nanjun to belong to Dongwu.

After capturing Yizhou, Nanjun became an important bridge connecting Jingzhou and Yizhou. Once Nanjun returned to Soochow, Liu Bei's troops would face two very difficult problems. The first problem is that Wu Dong can directly pass through the Yangtze River channel based on Nanjun, thus threatening Yizhou. The second problem is that the original occupied four counties in southern Beijing are likely to be gradually eroded by Wu Dong.

In other words, if Liu Bei returns Nanjun to Soochow, Shu Han will probably lose his presence in Jingzhou ahead of time, which is naturally the result that Liu Bei does not want to see. Therefore, this led to Liu Bei's reluctance to return Nanjun to Sun Quan, who had to get Nanjun, and the contradiction between the two sides gradually intensified, which eventually led to the historical event that Sun Quan sent Monroe to sneak attack on Jingzhou when Guan Yu visited Xiangfan in the north.