1, Cao Cao wants to influence Guan Yu. Guan Yu, the tiger general, chopped Hua Xiong with warm wine and killed Yan Liang and Wen Chou. Among all the hosts, he is like a tiger among sheep, brave and furious. Cao Cao has always attached great importance to talents, hoping to influence Guan Yu by being kind to him and finally put him under his command. So after Guan Yu's defeat, Cao Cao didn't kill him; Guan Yu left Cao Cao to find Liu Bei, but Cao Cao didn't kill him. At that time, wars were frequent, people were in dire straits, and everyone's life was at stake. If Liu Bei dies and Guan Yu has nowhere to go, maybe he will read the benefits of Cao Cao and take the initiative to go to Cao Cao. If Cao Cao completely conquered Liu Bei in the future and Liu Bei surrendered to the "imperial court" like Guan Yu, Guan Yu would naturally surrender to Cao Cao. So in the long run, Cao Cao didn't kill Guan Yu.
2. Cao Cao should take the initiative in morality. Guan Yu is a loyal man. He is an upright man and will repay his kindness. Guan Yu surrendered to Cao Cao, feeling that Cao Cao was very kind to himself and left him after making great contributions to Cao Cao. Guan Yu has always been obsessed with Liu Bei. Cao Cao gave Guan Yu a new shirt, but Guan Yu put it in an old shirt because Liu Bei gave it to him. Guan Yu said that the old shirt was worn outside, and seeing it was like seeing Liu Bei himself. Cao Cao gave Guan Yu a red rabbit horse, and Guan Yu thanked him again and again, saying that if he knew Liu Bei's whereabouts and rode on this horse, he could see Liu Bei within one day. Cao Cao said with deep feelings: "I don't forget my roots when I am in trouble, but I am a righteous man on earth!" " In addition, when Guan Yu surrendered to Cao Cao, there were "three covenants", one of which was that if he knew the whereabouts of Liu Bei, Guan Yu would go after him, and Cao Cao agreed. Cao Cao has Wang Ba's ambition, and he is bent on unifying all China. To this end, he wants to establish his own good image. Cao Cao didn't kill Guan Yu. First, his kindness to the righteous shows that he advocates justice. The second is to honor his promise and prove to the world that he is a man of his word, so that he can have the moral initiative.
Cao Cao wants to educate the soldiers around him. Guan Yu is a living textbook to educate the soldiers around him. It is said that Guan Yu hung up the golden seal and walked out of the city gate. Cao Cao's general Cai Yang wanted to lead troops to capture Guan Yu. Cao Cao stopped him and said to the soldiers who followed him, "Guan Yu has never forgotten his old master. He knows when he will come and when he will go. What a gentleman! You should all learn from him. " Good man Cao Cao went to the end and simply took dozens of people to see Guan Yu off. Cao Cao did this to make his subordinates understand that kindness and loyalty are the virtues that everyone must possess and the foundation for everyone to settle down in society. Loyal people are respected not only by their own people, but also by their enemies. Cao Cao didn't kill Guan Yu, but later executed Song Yang, a traitor seeking glory, which was different from others. They all aim to establish a correct orientation, so as to educate the soldiers around them and make them devote themselves to death.