In July 221, Liu Bei personally led the Shu Han army to attack Eastern Wu, when Liu Bei, spearheaded by the generals Wu Ban, Feng Xi, and Zhang Nan, led 30,000 men to capture the gorge, and defeated the Wu generals Li Yi, Liu A, and others, occupying Zigui, and then Liu Bei had the Zhenbei general Huang Quan stationed on the north bank of the Yangtze River to prevent Cao Wei's army from going south, and at the same time had Ma Liang go to Wuling to win about 20,000 soldiers of the local tribal leader Sha Moke, after which Liu Bei led a 50,000-strong army deep into Eastern Wu territory, posing a great threat to Sun Quan. At that time, Sun Quan, while declaring himself a vassal to Cao Pi, sent Lu Xun as the governor of Dadu and led 50,000 Wu troops to resist the Shu army, at that time, Lu Xun successfully blocked the Shu Han army's army by means of idle waiting, after which Lu Xun found an opportunity and burned Liu Bei's seven-hundred-mile company with a big fire, thus defeating the Shu army, but eventually Liu Bei fled back to Yong'an under the protection of everyone.
It has to be said that Liu Bei's launching of the Battle of Yiling seems to have been a bit hasty, and he does not seem to have analyzed too much the countermeasures and countermeasures of the Eastern Wu side, nor does he seem to have an accurate strategic goal, so that he will be expelled from the Wu Realm by Lu Xun, and the elite of the Shu Han Will be almost completely destroyed, the middle-aged and young generals will suffer heavy casualties, and the Shu Han talents will be faulted for a time. According to Liu Bei, he launched the Battle of Yiling to avenge Guan Yu, and some people believe that Liu Bei may have done so more to capture Jingzhou. So did Liu Bei launch the Battle of Yiling really for Guan Yu or for Jingzhou?
From the perspective of the topographical environment, after Shu Han and Eastern Wu signed the Xiangshui Alliance, the Jingzhou area occupied by Shu Han was about one-third of the Jingxiang area, but it was this area that provided Liu Bei with the initiative to develop to the east, especially the strategic place of Jiangling, which was both an indispensable entrance and exit to control the Three Gorges route and the hinterland of Jingzhou, as long as Shu Han occupied Jiangling, Shu Han did not have to worry about Eastern Wu across the river, and even Sun Quan had to always be on guard against shu Han's attacks, because of this. Both Lü Meng and Lu Xun had to send troops to sit at Lukou to prevent the Shu army from setting out from Jiangling and attacking Eastern Wu. Because of this, when Liu Bei launched the Battle of Yiling, his first goal was to conquer Jiangling, and even to subdue the four southern counties of Jingzhou, and after that, through strong military pressure, Jiangdong had to negotiate with Shu Han again to maximize the interests of Shu Han.
What's more, in the "Longzhong Pair", Zhuge Liang's strategic plan for Liu Bei was to cross Jingzhou and Yizhou before he could send troops to the Northern Expedition, so Jingzhou was a territory that Shu Han had to contend for. Although Eastern Wu could not annex Jingzhou in a short period of time, Jingzhou must be controlled by Shu Han, and only by holding Jingzhou in his hands could Liu Bei mobilize more resources and form a pinch attack on Cao Wei. And the momentum of Guan Yu's troops to besiege the two cities of Xiangfan in that year actually echoed Liu Bei's achievements in Hanzhong, and it was precisely because of the mutual influence between the two that there was a momentum of Guan Yu's later wei zhen Huaxia, which showed that there was no problem with the Northern Expedition strategy in "Longzhong Pair", and because of this, Liu Bei's Eastern Expedition was actually to prepare for the Northern Expedition again.
The most crucial thing is that Liu Bei at that time was already over the age of Hua Jia, for the people of the Han Dynasty, Liu Bei had reached the age when he could die at any time, and because of this, liu Bei could only use the momentum of his ascension to the throne to avenge Guan Yu's emotions to send troops, this was Liu Bei's last chance in this life, if he did not lead the army to march in person, he was afraid that in a few years, he would probably not have such a heart and courage. Just as in the past, Gongsun Zhan was able to occupy Youzhou because he dared to attack the nomadic thousand-man contingent with dozens of cavalry, Yuan Shao was able to unify Hebei because he dared to lead hundreds of soldiers to attack Gongsun Zhan with two thousand cavalry, but after that, both Gongsun Zhan and Yuan Shao were depressed and finally perished.
The author believes that the reason why Liu Bei launched the Battle of Yiling was actually because he learned the lessons of Yuan Shao and Gongsun Zhan, and did not want to be like Gongsun Zhan and Yuan Shao in his later years, and he could only give it a go for the future of Shu Han.