In fact, for Liu Bei, avenging Guan Yu was just a cover, and he wanted to attack Eastern Wu in order to capture Jingzhou. The importance of Jingzhou is self-evident to Liu Bei's clique, and the Shu Han Empire that lost Liu Bei in Jingzhou was only a divided regime and could not have much development. With Jingzhou, he was able to use this as a springboard to march to the Central Plains. It can be said that Jingzhou is the lifeblood of Liu Bei's group, so Liu Bei will inevitably choose to tear his face with Eastern Wu to seize the strategic place of Jingzhou. But why did Liu Bei take revenge after so long and then succeeded to the throne as emperor during this period?
Not long after Guan Yu's death, Cao Cao also died of illness in Luoyang. After Cao Cao's death, Cao Pi formally usurped the Han Dynasty to establish himself, which was more embarrassing for Liu Bei, who had been playing the Kuangfu Han Room, and if he was silent, he obviously tacitly acquiesced to Cao Pi's replacement of the Eastern Han Dynasty. In this context, Liu Bei's best choice was to call himself emperor. Liu Bei had been fighting for decades to revive the Han Dynasty, and he was now in his sixties. If you don't call yourself emperor at this time, I'm afraid I won't have a chance in my lifetime, after all, I always have to leave a name for my own efforts.
Less than a month after Guan Yu's death, Cao Cao died in Luoyang due to a head attack, after Cao Cao's death, Cao Pi forced Han to offer Emperor Chan to the throne, since then the Eastern Han Dynasty officially collapsed, the Cao Wei regime rose, since the Eastern Han Dynasty died, Liu Bei also claimed to be a descendant of the Han Dynasty, at this time Liu Bei said that the emperor's name was right, and after the establishment of shu Han, not only concluded his wish to be called emperor, but also won the hearts of the old subjects of the Han Dynasty, and Liu Bei naturally refused to let go of the good thing of killing two birds with one stone!