However, at this time, Sun Quan ordered Lv Meng to sneak attack Jingzhou. Guan Yu has always despised Mi Fang, the satrap of Nanjun County who stayed in Jiangling, and the general who was stationed in public security. In addition, during Guan Yu's Northern Expedition, Mi Fang and Shi Ren failed to supply materials in the rear, fearing that Guan Yu would come back to punish them, they surrendered to Lv Meng, resulting in Jingzhou being occupied by Wu Jun.
Guan Yu learned that the home front had fallen and hurried back to the army. As a result, due to the occupation of Jingzhou, the soldiers fled in succession, so they had to retreat to Maicheng, and were finally killed by Wu Jun.
Many people attributed Guan Yu's failure to his arrogance and contempt for Wu Jun, and there were too few troops left behind during the northern expedition to Xiangfan, which led to Monroe's opportunity. For example, the Romance of the Three Kingdoms adopted this statement.
However, judging from the relevant records, this statement is not true.
As early as the twentieth year of Jian 'an (AD 2 15), when Liu Bei captured Yizhou, Sun Quan sent troops to capture Changsha, Guiyang and Lingling because he could not claim Jingzhou. In order to recapture the three counties, Liu Bei personally led 50,000 troops to the public security, ordered Guan Yu to March into Yiyang, and confronted Wu Jun across the Xiangjiang River. Later, only because Cao Cao captured Hanzhong and Yizhou was shocked, Liu Bei was eager to go back and calm people, and he reached an agreement with Sun Quan to divide Jingzhou with Xiangjiang River as the boundary.
Although the matter was finally resolved peacefully, it shows that the Sun-Liu alliance has already cracked and it is impossible to be completely at ease. Therefore, when Guan Yu was in the northern expedition to Xiangfan, he not only set scouts and beacon towers along the Xiangjiang River to warn Wu Jun, but also left a lot of troops in Jingzhou.
Before Lu Meng sent troops to attack Jingzhou, he once told Sun Quan that Guan Yu led the army to the Northern Expedition, but left a lot of military forces behind. He suggested that he pretend to be ill and go back to Jianye for a vacation, and replace his position with an unknown Lu Xun, so as to win Guan Yu's heart and let him transfer the troops left in Jingzhou to the front line, thus easily capturing Jingzhou. This shows that Guan Yu left a lot of troops in Jingzhou.
However, it is different from the Romance in which Guan Yu transferred most of the defenders in Jingzhou. Historically, after Guan Yu learned that he was on leave, he only transferred his troops to the north, "slightly withdrawing troops to the fan", leaving a lot of troops. This can also be proved by the fact that after Mi Fang surrendered, other generals in the city also planned to ambush Lv Meng. If there are not many military forces in the city, obviously the defenders can't have such courage.
In addition, Jiangling is one of the most important strongholds of Han Shu Group in Jingzhou, and it is also a big city in Jingzhou after Xiangyang. This wall is so thick that it is easy to defend but difficult to attack. In addition, the siege technology in the Three Kingdoms period was still relatively backward, and the advantage of guarding the city was great. If Mi Fang does not surrender, but sticks to the city, even if Lv Meng has the military advantage, it is unlikely to seize Jiangling in a short time.
When Guan Yu learned that Wu Jun had attacked Jingzhou and retreated to the south, Cao Cao intended to use Guan Yu's hand to consume Wu Jun's strength, so he ordered the army not to pursue him and let him go. If Jiangling did not fall, Guan Yu's morale would not be shaken, and he would have a great chance to return to Jiangling safely.
So the direct cause of Guan Yu's death in history was Mi Fang's surrender to Dongwu.
However, even if Guan Yu returns to Jiangling safely, it doesn't mean that he will be fine.
Sun Quan ordered Lv Meng to seize public security and Nanjun, and at the same time ordered Lu Xun to lead his troops to capture Yidu, Fangling, Nanxiang and Zigui in the west of Jingzhou. In this way, the connection between Jiangling and Yizhou was cut off by Wu Jun, with Wu Jun in the south, Wu Jun in the east and Cao Wei in the west, making it an isolated city.
At this time, Wu Jun, after all, has a great advantage in strength. If Guan Yu and Jiangling rely on their own strength, it will be very difficult to defeat Wu Jun.
Therefore, the final result of this war depends on whether Liu Bei can break through Lu Xun's defense and reinforce Jingzhou in time. Judging from the later battle of Yiling, at this time, the Shu army suffered great losses in the battle of Hanzhong and has not fully recovered. Obviously, this is not an easy task.
Therefore, it is difficult to say whether Guan will finally escape.
To sum up, Mi Fang's surrender was the direct cause of Guan Yu's defeat and death so quickly. If he doesn't surrender, Guan Yu will probably come back safely. But even if Mi Fang doesn't surrender, it's hard to say what the final result of this war will be.