In 220 AD, emperor Xian of Han abdicated, Liu Bei was proclaimed the King of Hanzhong, and Sun Quan and Liu Bei had already formed a grudge (Guan Yu had lost Jingzhou). We analyze the strength of the three companies from three aspects.
name
First of all, Cao Wei, the Cao Wei regime Cao Pi has accepted the Zen concession of Emperor Xian of Han and has an orthodox position, at this time it is not important for Emperor Xian to vote for Liu Bei, after all, it is the eight classics of Zheng'er that give way to Cao Pi; Liu Bei at this time appointed himself as the king of Hanzhong, originally there was no orthodox status, all relying on his status as a relative of the Han Dynasty to have a certain righteous name, Emperor Xian's coming to vote at this time may have an encouraging effect on Liu Bei's clique, Liu Bei has a great possibility of placing Emperor Xiandi of Han under house arrest; Sun Quan has a legal system of forces on both, because of his grudge with Liu Bei. May be nominally subordinate to Cao Pi.
Therefore, Liu Bei was not nominally superior to Cao Pi, and Emperor Xiandi may also be a hot potato, which became the reason for the opponent's attack.
Power
In terms of comprehensive national strength, in terms of area, Cao Wei has two of the three worlds, and Shu Han is the smallest; demographically, the "Romance of the Three Kingdoms" records that at the end of the Three Kingdoms, the population of Shu Han was only 940,000 people, Cao Wei was 4.43 million people, and Eastern Wu was 2.3 million people (Zhuge Liang's several Northern Expeditions were tens of thousands of people, while Cao Wei was able to gather more than 100,000 troops in Yongliang, and Sun Wu also gathered more than 100,000 troops), in ancient times, it was actually a population war, so Shu Han was not dominant; the area available for cultivation in Shu Han was only the Chengdu Plain and Hanzhong region. Cao Wei, on the other hand, was several times larger than the North China Plain of the Chengdu Plain. Therefore, Shu Han was far weaker than Cao Wei in terms of national strength.
diplomacy
Shu Han formed a grudge with Sun Wu, resulting in Shu Han possibly facing Cao Wei, who had two of the three worlds, and Sun Wu, who had Jingzhou and Jiangdong (Liu Bei attacked Sun Wu immediately after becoming emperor).
From this point of view, Shu Han was far inferior to Cao Wei in terms of name, management, and diplomacy, and the only role that Emperor Xiandi of Han had on Shu Han was a little nominal role. Therefore, Shu Han still could not escape the fate of being destroyed by Cao Wei, and Liu Bei was even more impossible to unify, because Liu Bei died two years later