Why did Sun Quan treat Lu Xun so cruelly in his later period?

Anyone who has read the Romance of the Three Kingdoms knows that during the early period of Liu Bei's crusade, Lu Xun had a very good relationship with Sun Quan and wanted to wear a pair of pants. Then I trusted Lu Xun very much and basically gave all the relieving power to Lu Xun. Finally, Lu Xun didn't live up to Sun Quan's trust. A fire was used in Yiling, which destroyed all Liu Bei's hopes. The cause of Liu Bei's death was also closely related to the failure of this war. It can be said that Soochow has entered a relatively peaceful period since then.

However, after the Yiling War, Lu Xun returned to Dongwu, and he gradually lost the favor of Sun Quan. One of the big reasons was the clan problem. Sun Quan has not solved this problem well, and he has made a lot of efforts for this problem in his first few years in office.

Because Dongwu, unlike Cao Cao or Liu Bei, fought the world by themselves, it can be said that everything of the Sun family today can only be laid a good foundation here in Jiangdong with the top support of those clans in Dongwu. So at that time, Sun Quan was afraid that the strength of Lu Xun's family would develop, and then threatened the rule of the saying family, so he tried his best to weaken the power of these clans. At that time, there were four clans in Dongwu.

Of course, another important reason is that Lu Xun did something he shouldn't have done, that is, he intervened in the dispute over the prince, because the person Lu Xun wanted to support was different from the prince Sun Quan wanted to set up, which can be said to be diametrically opposed. But Lu Xun was very stubborn. He stubbornly wrote to Sun Quan, asking him to take his advice, and finally annoyed Sun Quan. Later, the Second Palace Rebellion persecuted Lu Xun and all of them to death.