The Southern Song Dynasty word Haoxin abandoned the disease has a grand finale of the "Yongyule Jingkou Beiguting Huaigu", which has a sentence: "Think of that year, Jinge iron horse, swallowed like a tiger." "It is about the grand situation during the Northern Expedition of Emperor Liu Yu of the Song Dynasty.
However, Liu Yu actually only achieved some stage victories, and did not completely succeed in the Northern Expedition.
In 417, Liu Yu sent a northern expedition from Jiankang(present-day Nanjing, Jiangsu), the capital of the Eastern Jin Dynasty, with the goal of dividing Later Qin around Guanzhong. At the same time, Liu Yu left his confidant Liu Muzhi to sit in Jiankang and deal with major military affairs. Soon, Liu Yu destroyed Later Qin and recovered Chang'an, the old capital of the Western Han Dynasty. But the bad news came immediately: Liu Muzhi died suddenly.
At that time, Liu Yu's position in the dprk was not particularly stable, and many people disobeyed Liu Yu, and thanks to Liu Muzhi's mediation, Liu Yu could go to the Northern Expedition with confidence. However, one of Liu Mu's deaths, no one in the DPRK, Liu Yu had to return to the division, the Northern Expedition was interrupted, and Guanzhong, which had just been occupied, was also taken away by Helian Bobo of the Great Xia Kingdom.
We might as well assume that if Liu Muzhi does not die, Liu Yu has no worries and concentrates on the Northern Expedition, can he really unify the world?
First of all, let's take a look at how many forces there are still in the world after Liu Yu destroyed Later Qin.
The strongest was naturally the Eastern Jin Dynasty controlled by Liu Yu, and liangzhou in the northwest, which is near present-day Gansu, and west of Zhangye was Xiliang, that is, the territory of Li Huan, the king of Western Liangwu Zhao, who was the emperor of the Tang Dynasty who recognized his ancestors; east of Xiliang, was northern Liang, controlled by the Xiongnu tyrant Xiongxiong Qu Mengxun; east of Northern Liang, now southwestern Inner Mongolia, Ningxia, and northern Shaanxi, was the famous Helian Bobo Kingdom.
However, none of these three small states combined could compare with Liu Yu's Eastern Jin Dynasty.
The territory of the Eastern Jin Dynasty at that time, the eastern front in the north reached the Yellow River, and the western front had controlled Guanzhong, including Shandong, Jiangsu, Anhui, Zhejiang, Fujian, Jiangxi, Henan, Hubei, Hunan, Sichuan, Chongqing, Guangxi, Guangdong, Yunnan, and Guizhou, with dense population, developed economy, and no problem with military resources and war resources.
Xiliang only has a few counties in Jiuquan and Dunhuang, and the population is sparse, and the same is true in Beiliang, that is, a few counties such as Wuwei and Zhangye, and the Kingdom of Bactria is simply a guerrilla, riding a horse, and fighting wherever it counts.
If Liu Yu sat in Chang'an, liu Muzhi's troops, grain, grass, and war materials raised in Jiangnan were continuously transported to Guanzhong, and Liu Yu was fighting a war of attrition with the western liang, northern liang, and great Xia states, without using swords, these three small countries could not last long, sooner or later it was Liu Yu's pocket.
Liu Yu was basically able to control the Hexi region, but his dream of unifying the world may also come to an end. Because next, Liu Yu had to face the strongest and most difficult enemy of the Eastern Jin Dynasty, the Northern Wei established by the Xianbei Tuoba clan.
In the late Western Jin Dynasty, the Xianbei Tuoba clan established the Daiguo in south-central Inner Mongolia, and in 376 AD, the Former Qin Heavenly King Jian sent troops to destroy the Daiguo, but more than ten years later, Former Qin was defeated at the Battle of Shuishui and collapsed rapidly, and Tuoba Jue, the grandson of Tuoba Shiyijian, the Daiwang, rebuilt the Daiguo and changed the name of the country to Wei, known in history as Northern Wei.
The Battle of the Founding of the Northern Wei Dynasty, which took place in 395 AD, was the famous Battle of Samhepi. In the battle, Northern Wei annihilated the main force of the strongest opponent at that time, Later Yan, and Later Yan weakened from then on, and was eventually destroyed by Northern Wei. At the time of Liu Yu's Northern Expedition to Later Qin, Northern Wei had already occupied Shanxi, Hebei, Jingjin, northern Henan, and the "headquarters" of central Inner Mongolia.
In terms of area, the Northern Wei Dynasty is naturally inferior to the Eastern Jin Dynasty, but if compared with the war resources, the Northern Wei is not inferior to the Eastern Jin Dynasty. In terms of population, Hebei and Shanxi are densely populated areas, especially Hebei, such as Jizhou, Zhao County, Wei County, Changshan County, and Zhongshan County, which were economically developed areas at that time.
If it is more than wood, bamboo, salt and iron, the Eastern Jin Dynasty may have more resources than the Northern Wei, but the Eastern Jin Dynasty lacked a very important war resource in the era of cold weapons - horses. And the Northern Wei Dynasty can say that there is no shortage of horses, that is, there is no shortage of horses.
The Northern Wei Dynasty controlled central Inner Mongolia, an endless steppe with countless horses. Although Liu Yu also had some cavalry, it was not worth mentioning compared with the almost inexhaustible cavalry resources of the Northern Wei.
In addition, the Northern Wei Dynasty was in the ascendancy period since the founding of the people, the emperor was Tuoba Si, very clever, would use people, and would use the Xiang soldiers for pleasure, and there was the Northern Wei version of Zhuge Liang - Cui Hao, wu had changsun Song, Mu Chong, Xi Jin, Shusun Jian, Yu Lilei, the strength of these people was not under the Eastern Jin Dynasty's powerful generals Tan Daoji, Wang Zhenxian, Shen Tianzi, Shen Linzi and others.
Moreover, in the face of the fierce Liu Yu, the Northern Wei did not actually take him seriously. When Liu Yu had just conquered Later Qin, Yi Yi, the Prince of Taishou of Qi Commandery, surrendered to Wei and wrote to Tuoba Si: "Liu Yu is now in Luoyang, as long as the Wei army sends troops to cut off Liu Yu's return route back to Jiangdong, Liu Yu can capture him in one fell swoop." However, Tuoba Si had no plans to go to war with Liu Yu for the time being, but he also affirmed Wang Yi's idea.
This shows that the Wei army has the strength to cut off Liu Yu's return road, and once it really does this, not to mention that the Jin army will definitely be defeated, at least it will be greatly affected in the military mentality. After all, the Jin army was all jiangdong disciples, and once the army's heart was scattered, the battle would not be easy to fight.
Another thing, Northern Wei originally did not intend to let Liu Yu cross the Yellow River, but was beaten by Liu Yu, learned to be obedient, and agreed to Liu Yu's use of the road to cut qin. However, Tuoba Si also gave the general Sun Song an order: Select elite generals and prepare for a decisive battle with the Jin army. If Liu Yu really wanted to cut down Qin, Changsun Song would lead his army south to attack Xuzhou and cut off Liu Yu's way back.
The reason why Tuoba Si did not move was that he mistakenly learned the Wei Emperor Cao Pi's "sitting on the mountain and watching the tiger fight". During the Three Kingdoms period, Liu Bei attacked Wu, and Cao Wei did not take the opportunity to attack Wu, but let the two tigers fight each other, and then Wei reaped the benefits of the fisherman. Tuoba Si also considered it this way, letting the Jin and Qin wars, and when both sides were defeated and injured, northern Wei came out again to clean up the mess. Tuoba Si believed that as long as Jin and Qin were both defeated and injured, he could cut off Liu Yu's head at any time.
Tuoba Si thought so, it was by no means whimsical, he had enough strength.
After Liu Yu destroyed the Western Liang, Northern Liang, and Great Xia kingdoms, he could theoretically attack Northern Wei from both the western (north-south direction of the Yellow River) and the southern line (the east-west direction of the Yellow River). However, the northern Wei forces could fight on two fronts. If Liu Yu made up his mind to destroy Wei, he was bound to fight a protracted war with Wei, and at the same time it would inevitably consume a large amount of national strength of the Eastern Jin Dynasty. How long the national strength of the Eastern Jin Dynasty could last, and how long the people of the Eastern Jin Dynasty could endure war, are unknown.
In fact, Liu Yu's rule in Jiangdong was not solid, and even if there was Liu Muzhi, who had a good relationship with the upper class, there were still many people who disobeyed Liu Yu. These people had little interest in destroying Wei and unifying the world, but they absolutely could not accept the destruction of Wei and cause damage to their own interests, otherwise, they would inevitably add chaos to Liu Yu within the Eastern Jin Dynasty, which Liu Yu could not bear.
Therefore, from a comprehensive point of view, Liu Yu wanted to destroy the Northern Wei Dynasty, and the Northern Expedition was successful, which was almost an impossible task.