Attacking from east to west, why was the Eastern Jin able to destroy the Chenghan, but the Eastern Wu could not destroy the Shuhan?
In the third year of Yonghe in the Eastern Jin Dynasty (347 A.D.), the ambitious general of the Eastern Jin Anxi, Huan Wen, attacked the Chenghan in the Sichuan Basin to the west. Before this, the situation in the world was very similar to that of the Three Kingdoms Wei, Shu and Wu Dingli. The Eastern Jin and Eastern Wu sites are similar, with the addition of Huainan and northern Jingxiang. The Chenghan and Shuhan sites are similar, and the northwestern Wudu and other places (Chouchi) are missing. Later Zhao occupied the Central Plains, similar to Cao Wei, but less Liangzhou (former Liang). There are also the Murong clan in Xianbei in the northeast, such as Gongsun Yuan in Liaodong. From the perspective of comprehensive strength, the ranking of the Three Kingdoms is Wei, Wu and Shu, and the same is true for the Eastern Jin. The strength is weaker than that of Hou Zhao, but stronger than Chenghan. Before Huan Wen attacked Cheng Han, there were many people who opposed it, but Yuan Qiao, the prime minister of Jiang Xia, thought that although Cheng Han's terrain was dangerous, his strength was not comparable to that of Hou Zhao, and he was easier to eat. It is also the southeastern forces that attacked the Yangtze River from east to west. Why did the Eastern Jin Dynasty succeed in destroying the Chenghan, but the Eastern Wu could not destroy the Shuhan? In the first year of Zhangwu of Shu Han (AD 221), Liu Bei, the lord of Shu, attacked Wu in order to report the loss of Jingzhou for killing Guan Yu. It is a pity that Liu Bei's soldiers were not secret, and he was set on fire by Lu Xun of the Eastern Wu Dynasty. This fire almost burned down most of Shuhan's national strength, and a large number of elites died in battle. At this time, it seemed that Sun Quan should take advantage of Yiling's great victory and go west to destroy Shu Han. Sun Quan did not do this, but negotiated peace with Shu Han and jointly dealt with Cao Wei. If Wu Jun destroys Shu, then the only route is to cross the steep and difficult Three Gorges from east to west, forming a long snake formation. This kind of attack method is just a copy of Liu Bei's attack on Wu. As long as the Shu army defends the Baidi City on the west side of the Three Gorges, one husband will be the gate, and ten thousand people will not open. Although the comprehensive national strength of Shuhan declined, there were still Li Yan and Chen Dao guarding the eastern front. Especially Liu Bei's confidant, Chen Dao, led the Baijue soldiers, which Zhuge Liang called "Western soldiers". More importantly, once Soochow's national power is contained in the Three Gorges, Cao Wei in the north will definitely attack Wu from the east. Cao Pi didn't listen to Jia Xu's advice, missed an opportunity to destroy Wu, and would never miss a second chance. Speaking of which, you may ask, when Huan Wen went west, was he not afraid that Hou Zhao in the north would take the opportunity to attack the Eastern Jin from the east? The two situations are different. The northern line of Soochow Wu was only in the narrow and long area along the river north of the Yangtze River, which was not conducive to the large-scale use of troops by the Wu army in the north of the Yangtze River. The Eastern Jin Dynasty basically controlled the Huaihe line of defense except for Shouchun. Everyone knows that "guarding the river must guard the Huai". With the Huaihe line of defense, Hou Zhao faced many difficulties when he wanted to attack the Eastern Jin Dynasty. Later Zhao had to fight a protracted battle for Huainan with the Eastern Jin before he could drink horses on the Yangtze River. Chai Rong, Zhou Shizong of the late Five Dynasties and Ten Kingdoms, was somewhat similar to Han Gaozu. With Chai Rong's heroic strategy, he fought for Huainan with the Southern Tang Dynasty, which was under the reign of the king and the minister. Cao Wei controls most of Huainan, especially Hefei, a strategic city, and it is relatively easy to attack Wu. In 263 AD, Sima Zhao, a minister of the State of Wei, sent Deng Ai and Zhong Hui to attack Shu, and Liu Shan, the ruler of Shu, surrendered. At this time, the national strength of Soochow Wu is still strong. Is it possible to take the opportunity to attack Shu at this time? Lord Wu Sun Xiu did exactly that. Before the demise of Shu Han, they sent people to ask Soochow for help, Soochow just pretended to rescue, and really wanted to try to Shu. But Sun Xiu faced the same situation as his father Sun Quan, and he could only take the road of the Three Gorges in order to plan Shu. At that time, although the Shu Han died, Luo Xian, the prefect of Badong, was defending Yong'an. The Wu army attacked Yong'an in a large scale, and was defeated by Luo Xian for the first time, and then sent Lu Kang to lead 30,000 reinforcements. Restricted by the geographical disadvantage, and the Jingzhou soldiers of Cao Wei came to the rescue, Soochow had to retreat. After more than 100 years, the geography has hardly changed. Why did Huanwen not have so many problems in his attack on Shu? In Yuan Qiao's words, "Li has no way, the people's heart is not attached, he holds the (Shu) danger far away, and he does not cultivate war preparations." It is incomparable with Shu Han ruling Shu as the Han Dynasty clan. Liu Chan was complacent but not cruel, Li Shi was greedy for money and lust, often killing other people's husbands and accepting their wives, punishing ministers at will, and everyone was in danger. The national strength of the Eastern Jin Dynasty is rising, and it is blessed by the status of the "Jin Dynasty Royal Family", which is far more attractive to the people of Shu than Di Li. After the Jin army entered Shu, it was almost like a broken bamboo. That is to say, the battle of Zangqiao encountered a little trouble, but by accident, it also mixed in, forcing Li Shi to surrender. The Eastern Jin attacked Chenghan, and the Houzhao in the north were in constant trouble, and they had no energy to manage Huanwen at all. Later Zhao emperor Shi Hu focused on attacking Qianliang. Once Qianliang broke through Longxi and entered Guanzhong, Hou Zhao would be in big trouble. Qian Liang didn't seem to be able to attack Guanzhong yet, but Hou Zhao Dajun was repeatedly humiliated by Qian Liang in Longxi, unable to advance or retreat. This was an advantage that Soochow Wu did not have at that time. Whether it was Cao Wei (Cao Cao, Cao Pi, Cao Rui) in the early stage, or the Sima Clan in the later stage, the Central Plains controlled by them did not have a strong opponent like Qianliang.