Guan Yu was the number one general of the Shu Kingdom, he was arrogant, in the Jingzhou War, he was not fully prepared, resulting in a sneak attack on Eastern Wu's back, which was a major strategic mistake he made, but honestly speaking, his failure could not all blame him, at that time, who could have imagined that Mi Fang and other old ministers who had followed Liu Bei for most of their lives would fall without a fight because of a scolding? This psychological endurance is also too weak. Therefore, Guan Yu's defeat cannot all be regarded as a "crime of war".
If Guan Yu was able to escape back to the Shu kingdom, Mi Fang's betrayal might become his shield and a reason for Liu Bei and Zhuge Liang not to kill him.
Of course, some people say that Liu Bei and Zhuge Liang actually wanted Guan Yu to fail, otherwise why didn't Liu Bei send someone to support him after fighting in Xiangfan for so long, obviously wanting to kill people with a knife and get rid of Guan Yu. This statement is too conspiracy theory, and it is not at all reasonable, even if Guan Yu and Liu Bei have a contradiction, this contradiction is also an internal contradiction and a secondary contradiction, and their external contradiction with Wei and Wu is the main contradiction.
Liu Bei did not send troops to Guan Yu to support, mainly because Guan Yu fought too smoothly at the beginning, so that Guan Yu and Liu Bei felt that there was no need to send troops to support, but what they did not expect was that the defeat of the army was like a mountain, and Guan Yu only took about half a month from victory to defeat, which was too fast, I am afraid that when Liu Bei learned of Guan Yu's defeat, Guan Yu had already been defeated and killed.
Liu Bei was definitely not stupid enough to abandon Jingzhou and hundreds of thousands of troops in order to get rid of Guan Yu, which could not be more stupid. Even if Liu Bei wanted to get rid of Guan Yu, it should be after the victory of the war, even if he really wanted to unload and kill the donkey, he would have to wait until the donkey had finished grinding things before unloading and killing. Judging from the situation at that time, Guan Yu was still the most capable and prestigious general in the Shu kingdom, and no one among the shu generals knew Jingzhou better than him, so he would definitely continue to be appointed as the candidate to recover Jingzhou. The pot of failure will not be betrayed by Guan Yu, Liu Bei will say that Eastern Wu has betrayed his faith, and Mi Fang has defected.
Liu Bei is still quite benevolent in terms of how to behave in the world, and the feelings between him and Guan Yu are extraordinary, some scholars believe that it is even better than the relationship with Zhang Fei, before Zhang Fei drank and lost Xuzhou, Liu Bei did not blame him, now how could he kill Guan Yu?