Cao Cao began his career of conquering Huangta Army in his twenties, thinking that it was his wish to make contributions to the country. After that, he fought for nearly 40 years, almost every year, but unfortunately failed to unify the whole country.
If the reason, the most direct or look at the military. After defeating Yuan Shao, Cao Cao had at least two chances to unify the world-the battle between Battle of Red Cliffs and Hanzhong. Battle of Red Cliffs's eve was the closest he came to reunification. At that time, Beiding and Jingzhou surrendered. Liu Bei, regarded as a confidant, fled all the way, leaving only the shaken Jiangdong regime. Judging from Cao Cao's letter to Sun Quan, he was quite arrogant and took Jiangdong as a bag.
But in fact, he attacked Jiangdong immediately after taking Jingzhou, which was a big mistake made by rash advance. Jia Xu also advised him: "If you use the compassion of Lao Chu to entertain officials, appease the people and make the land happy, then you will be easily persuaded by Jiangdong." . Cao Cao refused to listen and was aggressive because he regarded Sun Quan as a willing child and underestimated Jiangdong's determination and ability. Unexpectedly, Sun Quan's ambition is not smaller than that of Yuan Shao and others. Lu Su once said to Sun Quan in public: "May the supreme weeds be added to the world, sum up Kyushu and become an emperor." Sun Quan said with a smile: It can be seen that he did not declare his ambition to be an emperor. How could he surrender easily? Liu Cong surrendered because Liu Biao had no ambition and no self-protection. As the saying goes, father and son are ambitious people. Cao Cao is too simplistic.
Second, he underestimated Liu Bei. Liu Bei has been fighting with him for many years and has been passive, taking walking as the best. However, Liu Bei, who was in Jian 'an for thirteen years, is not what he used to be. Zhuge Liang can not only persuade Sun Quan to resist Cao Cao, but also form an equal diplomatic alliance with him. The latter point is particularly important, which ensures that Liu Bei is no longer just a vassal of local warlords as in the past, but is qualified to compete for his own territory. Liu Bei was already at the end of the road, but suddenly he turned defeat into victory, occupied Jingxiang and United with Sun Quan, laying the foundation for three points in the world. Without Liu Bei's participation and alliance, Cao Cao only faced Sun Quan, a powerful enemy. Even if Chibi fails, he may find another chance to win. However, it will be extremely difficult to break the balance when the three forces participate and restrict each other. For example, in the twenty years of Jian 'an, Sun and Liu fought for Jingzhou, and Zhang Lu always surrendered to Cao Cao. The two families immediately divided their spheres of influence and turned their guns. Liu Bei returned to Shu, and Sun Quan attacked Hefei with 100,000 soldiers. Later, Cao Cao gave Zhuge Liang five pounds of precious chicken tongue incense as a thank you. At this time, it is obviously too late to dig the corner again. Who told him not to get rid of Liu Bei when he was cooking wine and talking about heroes, leaving behind endless troubles.
After Battle of Red Cliffs, Cao Cao lost hundreds of thousands of soldiers, which was difficult to recover, while Ma Chao and Han Sui even took the opportunity to occupy the west of Tongguan. His rule over the north was too dangerous to take care of. He can only sit back and watch Liu Bei invade Jingzhou and send troops for profit. Since then, the nature of his war has changed from a war of unification and expansion to a war of strategic importance, and three tug-of-war battles have begun to take shape.
The battle with Liu Bei in Hanzhong was another turning point. Zhang Lu's surrender was a very favorable opportunity, and he chose to continue to send troops to Shu. As Sima Yi said, Liu Beichu's interests are unstable. If Cao Cao uses Hanzhong to give up, the other party will "collapse". Cao Cao returned a famous saying, "After you get Gansu, you can see Shu." Cao Cao certainly has his own considerations. Maybe he has learned from his long-term failure.
Why didn't Cao Cao do anything in these four years, which caused all his previous efforts to be in vain? Let's look for the reason from Cao Cao's court. In the eighteenth year of Jian 'an, Cao Cao called, like the story of Xiao He. Cao Cao's later activities focused more on politics. Although he tried his best to be attentive to Wang in his early years, he did not disobey him, but it is obvious that Hanzuo's downfall is irreversible. Even though he has his own scruples, he is convinced of his fame and position. Cao Cao is old, paving the way for future generations.
After Liang Wudi's reign, Cao Cao was promoted by the Emperor of Heaven almost every year in the eighteenth year of Jian 'an. It is conceivable that there are complicated orthodox disputes and political procedures behind this. Correspondingly, the army is getting thinner and thinner. By the twenty-five years of Jian 'an, there were only two major military operations, namely, pinglongxi Liangzhou and capturing Hanzhong, in which Hanzhong gained one and lost the other. Sun Quan's two conquests ended hastily under favorable circumstances. After the first return, Cao Cao ascended the palace and was awarded the banner of the son of heaven by Xian Di for the second time. Is there a connection?
Cao Cao also lost his most important adviser, Xun Yu, because of the so-called Gong Wei, which also affected his military decision-making to some extent. At that time, Xun Yu went to capitals for many times to urge Cao Cao to welcome Emperor Han Xian, but the purpose was to hope that Cao Cao would take this opportunity to "serve his master, handle affairs impartially and help Hongyi". It was his principle to help protect the Han Dynasty, and he died for it. Xun Yu, who followed Cao Cao for many years, remained loyal and made many contributions. This shows the political pressure felt by Cao Can.
The so-called "relying on the emperor to make the princes" brought Cao Cao political capital, which is probably far less than the political pressure it brought. Although Mao Jie advised Cao Cao that "it is advisable to take the son of Fengtian as a minister", in fact, after Cao Cao married the son of Fengtian in the first year of Jian 'an, he was faced with "Yuan Shao's dissatisfaction. The reason why Mao was in the east of Lu Bu and refused to go south was only in the Central Plains. There are still Xianbei, Li Liang and other ethnic minorities living in Wuhuan in the west, and there are still warlords such as Liu Biao, Zhang Lu and Sun Ce. Because Cao Cao occupied the central area, no one joined in. However, Cao Cao's most effective counselors and brave soldiers rarely came to the door to respond to the imperial conquest. Whether attracting talents or expanding the sphere of influence by attacking cities and plundering land, in Lv Simian's words, it is because he is "politically clear and good at fighting".
On the other hand, because he was welcoming the Phoenix Emperor, Cao Cao took the responsibility of the Han Dynasty on himself and became the target of public criticism. When Zhou Yu called Han Xiang a thief, Xun Yu was full of expectation for him to come back to life. Huang San, who unified China before, never faced such complicated and contradictory political situation and legal problems. With the increase of Cao Cao's power, there are more and more political enemies. He has to try to solve these problems, such as offering three daughters, killing the queen's family and punishing Kong Rong. How to balance the relationship between the Han Dynasty and himself cost Cao Cao a lot of energy. Contrast two rivals: Hou Jiangdong in Battle of Red Cliffs doesn't care about the imperial court, and Liu Bei claims to be orthodox. There is almost no internal struggle between the two families, so they can unite with each other and consolidate themselves.
The resistance of the gentry to Cao Cao should not be underestimated. In the peace talks, Chen Yinque called Cao Cao's regime "Legalist Cao Wei's regime". Cao Cao was born in a eunuch family who was discriminated against by the gentry most, and began his military career. He is a meritocracy, does not believe in destiny, enforces the legal system, and suppresses mergers, all of which run counter to the ideas of the gentry. Xun Yu's death was also related to his aristocratic background. Until Cao Cao's death, Cao Pi appointed Chen Qun to implement the system of "Nine Grades Being Right", and the cremation monopolized the right to be an official. Then the official positions were allocated according to prestige, threshold and power within the gentry, which really eliminated the doubts of the gentry and gained their recognition of Cao Pi's generation of Han. Therefore, when Cao Cao was alive, he never had a strong cohesion for the cremation groups all over the country. Although the gentry groups in the Central Plains have many subordinate relations with local and orthodox ideas, local groups such as Jingxiang, Yizhou and Jiangdong do not buy it. On the other hand, the regimes of Liu Bei and Sun Quan were strongly supported by the gentry group. Zhuge Liang himself came from Langya cremation and had many marriages with Jingxiang cremation. As an outsider, Liu Bei's stable position in Jingxiang largely depends on the support of local gentry such as Zhuge Liang, Pang Tong and Ma Liang. His sudden comeback is not the same as the previous wolf situation.
As the saying goes, when you are busy outside, you have to be quiet inside. When you worry about your inner problems, you have to worry about your lungs. Sun and Liu are outstanding people. They are too busy now. Cao Cao is the oldest of the three. Even after several years, I'm afraid he has no intention of reunification.