Killing people with a knife is a very clever strategy, which can get rid of other people's enemies without harming their own interests. During the Spring and Autumn Period and the Warring States Period, many famous counselors used this strategy to go to the battlefield and received good results. Liu Bei also skillfully killed a generation of famous Lu Bu with this strategy.

Although Lu Bu's martial arts is very high, his character is really not very high, otherwise he would not be called a three-surname domestic slave by Zhang Fei. Liu Bei's hatred for Lu Bu can be said to have accumulated for a long time. At that time, Lu Bu took refuge in Liu Bei, and Liu Bei trusted him. Unexpectedly, Lu Bu betrayed Liu Bei and directly cooperated with the spies to seize Liu Bei's city. Is there any reason for this deep hatred? In addition, Lu Bu is ready to surrender to Cao Cao. If he succeeds, Wei Jun will be even worse, and Liu Bei's strength is not as good as Wei Jun's, so the gap will be even bigger, and Cao Cao has always cherished talents. For a military commander like Lu Bu, Cao Cao has absolutely no reason not to accept it for his own use, so in order to avoid the enemy's power becoming bigger, Liu Bei's action to kill Lu Bu is imperative.

Liu Bei's plan to kill Lu Bu was blocked. In order to avoid the loss of his own strength, Liu Bei intends to get rid of Lu Bu with the help of Cao Cao. In this way, Liu Bei not only revenged Lu Bu's betrayal, but also weakened Wei Jun's strength, killing two birds with one stone.

Liu Bei's plan can be said to get rid of Lu Bu as easily as blowing off dust, which is a model of the case of murder by aiding others. He took advantage of Cao Cao's suspicious character and Lu Bu's past betrayal of the monarch. When Lu Bu surrendered to Cao Cao, he told Cao Cao about Ding Jianyang and Dong Taishi, which successfully aroused Cao Cao's suspicion of Lu Bu, and finally made up his mind to listen to Liu Bei and kill Lu Bu.