While in reality Cao Cao did leave Dong Zhuo, the tyrannical warlord who held the last Han emperor hostage in 190 to form his own army, the Romance of the Three Kingdoms went a step further to describe Cao Caos attempted assassination of the latter:
Since Dong Zhuo deposed the eldest son of the late Emperor Ling and placed in the throne Emperor Xian, his tyrannical behavior had angered many court officials. One of the officials, Wang Yun, held a banquet one night. Halfway through the banquet, Wang Yun began to cry at the cruel deeds of Dong Zhuo. His colleagues, feeling the same anguish, joined him.
Cao Cao, however, laughed and said, "All the officials of the court – crying from dusk till dawn and dawn till dusk –could you cry Dong Zhuo to his death?" He then borrowed from Wang Yun the Seven Gem Sword with the promise that he would personally assassinate Dong Zhuo.The next day, Cao Cao brought the precious sword along to see Dong Zhuo. Having much trust in Cao Cao, Dong Zhuo received the guest in his bedroom. Lü Bu, Dong Zhuos foster son, lift the room for the stable to select a fast horse for Cao Cao, who complained about his slow ride.
(Cao Cao )
When Dong Zhuo faced away, Cao Cao prepared to unsheath the sword. However, Dong Zhuo saw the movement in the mirror and hastily turned to question Cao Caos intention. At this time, Lü Bu had also returned. In his desperation, Cao Cao kneltand pretended that he wanted to present the sword to Dong Zhuo. He then rode away with the excuse of trying out the new horse, and headed straight out of the capital before Dong Zhuo, who grew heavily suspicious, could capture him.
Following the escape from Dong Zhuo is a legendary episode aimed at illustrating Cao Caos near-Machiavellian tendenciesfor later characterizations of him as a villain. Though never 
exactly proven, it is said that Cao Cao escaped with one retainer, Chen Gong to the home of an old friend of his, perhaps his fathers sworn brother, from whom he was able to beg shelter. He promised to protect him, and then set out to gather materials for an evening feast. Cao Cao and Chen Gong hid themselves in a back room, where they chanced to overhear a discussion by some servants involving some sort of murder plot. Assuming that his fathers sworn brother had deceived him and intended to hand his corpse to Dong Zhuo for a
reward, Cao Cao and Chen Gong burst in on the servants and proceeded to massacre the entire household, including the wife and children of his friend, whereupon he discovered that the "murder" he overheard pertained not to him, but to a pig intended as the centerpiece of the feast.
Cao Cao and Chen Gong immediately fled but encountered his fathers sworn brother returning from his errand at the houses front gate. When questioned, Cao Cao gave him the excuse of fear of having been followed as the reason for his abrupt departure, and when he turned to continue toward the house, Cao Cao again unsheathed his sword and stabbed him through the back. When questioned by Chen Gong as to the reason for such a horrible action, Cao Cao explained that if hehad returned to the house and see what had been done, he would have immediately run to the authorities desiring vengeancefor his family, and their plight would be even more precarious than it already was.
( Dong Zhuo )
Cao Cao then lifted high his bloody sword and made the quote that would forever secure his place as the foremost villain in Chinese popular literature: Ningjiao wo fu tianxia ren, xiujiao tianxia ren fu wo, meaning "Better that I should wrong the world than that the worldshould wrong me."
