1. North-south confrontation and south-east fundamentals

> .  .The formation of this situation actually has its geographical basis.

The confrontation between the north and the south in history was mostly a confrontation between the northern ethnic minority regime and the southern Han regime. In addition to the brief confrontation between Sun Wu and Cao Wei (Western Jin), other confrontations between the north and the south that have occurred in Chinese history, such as the Eastern Jin and Southern Dynasties and the Sixteen Kingdoms Northern Dynasties, the Southern Song and Jin, and the Southern Song and Mongolia (Yuan), the northern regimes were all established by ethnic minorities. The political and military confrontation was based on the geographical environment, production and lifestyle they were in.

China's territory has a large span of north and south, and the climate, environment and human habits are quite different from that of north and south, which leads to great differences in military expertise between the north and south.

The northern ethnic minorities are nomadic and hunting. Men are all riding on cavalry, usually nomadic, hunting, and going out to fight during wartime. They can be said to be the unity of soldiers and civilians. In terms of strategy and tactics, they are good at long-range attacks, and cavalry are good at field battles. They focus on personal enthusiasm, and people fight on their own; they grow in the north, learn to be cool and cool, and are not tolerant of heat and heat, so their combat in the south is mainly in the autumn and winter seasons. In the autumn and winter seasons, the autumn and the horses are fat, the earth is solid and clean, which is conducive to the cavalry's driving.

The Han people in the south take farming as their business. The society is highly civilized, and the society is highly organized. The use of water conservancy is the main feature of their society. Their military management and military use are also consistent with the characteristics of their environment, production and lifestyle. Military management is well-known for organization, order and discipline. In history, the more famous troops in the south, such as the Beifu Army, the Yue Family Army, the Qi Family Army, and the Hunan Army are all well-disciplined and well-trained. In terms of strategy and tactics, they pay attention to strategy, pay attention to the formation of the troops, are good at using cities as strongholds to defend, and use rivers and waterways in plain areas for transportation. Establish a navy. The active use of troops to the north in the south is mainly in the chūn summer season. The chūn summer season is the rainy season in the eastern monsoon region of China, and the rivers are rising, which facilitates the use of rivers and waterways for transportation and delivery of manpower and material resources.

Both the north and the south have their own strengths and their own strengths. Given the characteristics of the climate and terrain of the Central Plains, both the north and the south have pros and cons in terms of time and place. Those who benefit the south are not conducive to the north, and those who benefit the north are not conducive to the south. Both sides have the opportunity to play to their strengths and take advantage of the other's weaknesses.

During periods when the north-south confrontation is relatively stable, the two sides often reach a balance of power. The confrontation between the two sides stabilizes on a middle line between the Yangtze River and the Yellow River. As long as either side crosses this middle line, it will face great difficulties and will also encounter great resistance. This middle line is usually the Huai River in the eastern region. Although the southern forces can occasionally reach the Yellow River and the northern forces can sometimes drink the Yangtze River, the two sides are generally stable on the Huai River line; in the western region, the Qinling Mountains are usually bounded.

The Huanghuai Plain is the main battlefield for the north-south battle. The seasonal changes in this area are quite obvious, with both vast fields and lateral rivers. In autumn and winter, the earth is solid and clean, and the vast fields are suitable for the north to drive, which is conducive to the north to play the strengths of cavalry in field battles; in summer, rivers and waters rise, which is conducive to the south to play the strengths of water wars and city defenses. Therefore, both sides are half-mixed in terms of timing and place, so it is easy to fall into a tug-of-war battle.

The elders of the south are not as good as those of the southeast. The southeast is located in the subtropical zone, with a lot of rain and rivers crisscrossing the rivers. The Yangtze River and the Huai River flow in the east and west, scattering between the north and south. With their tributaries, a dense river water network is enough to buffer the impact of the northern cavalry. In terms of blocking the impact of the northern cavalry, the Yangtze River is indeed an insurmountable natural barrier. The south can use these river waterways to build military strongholds, guard some major channels, and give full play to its strengths in water warfare and city defense. In the entire southern region, no region can have so many river waterways as the southeast. In addition, the rainy season in the south is humid and hot, and the northern people and animals are not adapted. In this way, if the northern forces cross the Huai River and continue to go south, they will face huge climate and environment difficulties, and find that they have been trapped in an unfavorable situation of abandoning their strengths and being short of their weaknesses.

The economic conditions in the southeast region are also relatively good. The Taihu area in the lower reaches of the Yangtze River is a wealthy economic zone, densely populated. During the Western Han Dynasty, King Liu Bi of Wu used "cast mountains and boiled the sea, and the country's use of rich people" and attracted the desperation in the world with his strong economic strength. Sima Qian described the economic situation at that time, saying, "Wu, there are the sea salt in the east, the copper in Zhangshan, and the benefits of the three rivers and five lakes, which are also the city in Jiangdong." [   Note: Volume 129 of "Records of the Grand Historian" Biography of Merchant and the Development of the Jiangnan Economics]  The development of Jiangnan was relatively later than that in the north, but the turmoil in the north would lead to a large number of refugees moving south. The refugees brought advanced production technology to the south, promoting the development of Jiangnan and the development of Jiangnan economy.

The turmoil in the late Eastern Han Dynasty caused the peak of the migration of refugees in the south in Chinese history. After the "Yongjia Rebellion", the great tribes and people in the Central Plains moved south again. The refugees from the north moved south one after another, promoting the economic development of the southeast region. By the time of the Southern Dynasty, Yangzhou, known as "Jibaidao" in "Yugong", had already shown a very prosperous scene. Shen Yue of the Southern Dynasty once described the prosperity of the economy in the Jiangnan region and lamented: "The country is prosperous in Jiangnan!" He praised the Kuaiji area for "with sea and lakes, and the good fields are hundreds of thousands of hectares, with fertile land worth one gold acre. (Guanzhong) Yu and Du, which cannot be compared." He praised the

The state "has the fertile Wu, the profit of fish, salt, and qizi, filling all directions, silk, cotton, cloth and silk, covering the world."  [  Note: Volume 54 of "Book of Song" Volume 54 "Book of Song" 14 "Historical Ministers"]    During the Daming period of the Liu Song Dynasty, Yangzhou's population density was several times that of other large states, and the population of only one county in Kuaiji could be compared with the Jing, Jiang and other major states at that time. During the Sui and Tang Dynasties, the southeast wealth was highly valued by Guanzhong, and Yangzhou's wealth was always the best in the world, and it was called "Yang Yi Yi Er" at that time. The Grand Canal opened the Sui Dynasty and the Tang Dynasty governed the canal, and they all had the intention of transferring the southeast wealth to supply Guanzhong. The capitals were built in the Yuan, Ming and Qing dynasties.

jīng, economically, it also relies on the southeast to re-draw the Grand Canal to transfer the Southeast wealth to the capital. There are many rivers and rivers in the southeast, and the transportation is convenient and scarce things are easy to be supplemented. In addition, the Shanghai Transportation makes its transportation and trade more extensive. These conditions provide an economic foundation for the political and military status of the southeast.

In ancient times, the customs of the southeastern region were strong, brave and martial, which was also a condition that the regime based in the southeast could rely on. The "Han Book" Geographical Records recorded the customs of the southeast, saying, "The kings of Wu and Yue all like bravery, so their people are still good at using swords, and they are easy to get out of death." [  Note: Volume 28 of the "Han Book" Geographical Records"]   In the autumn, Wu Yue was able to compete with the Central Plains powers such as Qi and Jin. Xiang Yu led 8,000 children from Jiangdong, which made the Qin people scared, all thanks to the brave and martial style of the southeastern region. The "Sui Book" Geographical Records describe the customs of the southeastern region, saying that the Huainan area "people are both restless and vigorous, with decisive style, and they are responsible for disasters, and they are willing to die, and they are more deceitful when fighting. This is the old style.

Later, the customs changed a lot, and they were honest and frugal, frugal, and were gradually polite. "The Jingkou area "is both accustomed to war and called the world's soldiers. The custom of using May 5 as a fighting drama, with each material being strong and weak, and each other talking about martial arts." The eastern Zhejiang and Jiangxi areas were also quite similar. [  Note: Volume 31 of the Sui Book of Sui     Geographical Records]    Especially in Huainan, it was a place where refugees moved through the past dynasties. The refugees had many ethnic groups, and were used to war and displaced, forming armed forces to protect themselves. This is a potential armed force that can be used. During the Eastern Jin Dynasty, Xie Xuan and Liu Yu led the Northern Palace soldiers who repeatedly defeated the strong enemies in the north. This is a manifestation of this force.

Most regimes established in the southeast can unify half of the south of the Yangtze River and form a confrontation between the north and the south with the north, which has a lot to do with the social foundation of the southeast regime.

The southeast regimes are mostly house-relocated regimes, which are the true and conservatives of the traditional Chinese politics and the advanced culture of the Central Plains. After the Central Plains regime moved to the southeast, the advanced social and political culture of the Central Plains formed an important basis for their rule. After the northern ethnic minorities occupied the northern region, most of the southeast regimes were able to integrate southern society and unify half of the southern part of the Yangtze River, which is a very important factor. However, there is also a problem of the combination of house-relocated forces and local forces. The establishment of the country of Jiangdong by Sun Wu was the product of the merger of the Huaisi Group and the Jiangdong clans; the Jin Dynasty moved south, and it was also a combination of the Central Plains Kings, Xie, Yu, Huan and other major tribes with local Gu and He prestigious tribes, which established a firm foothold in Jiangdong.

Since the Jin Dynasty moved south, the Central Plains gentry and people took refuge in Jiangdong, bringing the advanced culture and production technology of the Central Plains into Jiangdong, and the Eastern Jin Dynasty protected Jiangnan, and resisting the north for hundreds of years, moving the gentry was an important stable factor. As the Jurchens and Mongolia successively entered the Central Plains, the Zhao Song Dynasty moved south again, and the southeast once again became a gathering place for the social, political and cultural centers of the Central Plains. The influence was profound. The prosperity of the Southeast people in the Ming and Qing dynasties and modern times was eye-catching.

The house-moving regime has the advantages mentioned above, but the house-moving regime itself is a product of forced migration by powerful enemies, so it is inevitable that it is a characteristic of being calm and unwilling to make progress. Historically, most of the regimes based in the southeast took the Northern Expedition and regaining the Central Plains as the slogan, but very few were truly successful in the Northern Expedition. Most of the regimes based in the southeast can unify half of the southern part of the Yangtze River and form a confrontation with the north and south, and rarely can unify the world (only Zhu Yuanzhang of the Ming Dynasty is the exception), which is related to the special feature of the house-moving regime.

2. Jianghuai Defense System

The entire Southeast defensive pattern is a multi-level defense system based on the Yangtze River and Huai River.

The regimes established in the southeast mostly took Jiankang (now Nanjing) as the political focus. Jiankang, as the capital of Jiangnan, had unique conditions. Jiankang was located in a dangerous place and had convenient transportation. It connected to Bashu and Jingxiang in the west, connected to Sanwu in the east, and two Huai in the north. Bashu and Jingxiang were enough to protect the upstream; the three Wus were rich, enough to provide manpower and material support; the two Huai areas were the places where the attack and defense advance and retreat, and all attack and defense should be based on Jiankang.

Jiankang itself "beared the river in front, and was surrounded by Chongling in the south, and was in the deep and strong position. The situation was unique." In ancient times, there were many hills around Nanjing City, such as Zhongshan, Zhoushan and Mufu Mountain. Sun Wu was originally built here, and Zhuge Liang called it "Jinling, Zhongshan, Longpan, Stone Tiger, and Imperial House." [  Note: "Reading History Fangyu Ji" Volume 20 Jiangnan 2]  The Jin Dynasty moved south and also built its capital here. Later, Song, Qi, Liang, and Chen frequently evolved, but did not change the old way; after the Liang Dynasty experienced the "Hou Jing Rebellion", it changed its capital to Jiangling, but it soon died in the Western Wei Dynasty. The Southern Tang Dynasty, among the Five Dynasties and Ten Kingdoms, also established its capital here; after the Ming Dynasty unified the country, it also established its capital here, and although it later moved its capital to běi jīng, Jinling has always been a capital. In modern times, Nanjing also became the capital of the Taiping Heavenly Kingdom and the Republic of China.

The south relies on the fight against the north, mainly relying on the Yangtze River and the Huai River. The formation of some important military cities in the south are based on this. (See Figure 2-3-l)

The Yangtze River runs across the east and west, extending thousands of miles, and its tributaries connect a vast area. The Yangtze River connects Bashu on the east, Jingxiang on the middle, Wuyue on the east, and the upper and lower reaches echo each other, making the situation in the entire southern region complete. In addition, the Yangtze River itself plays a natural barrier to block the impact of the northern cavalry. Emperor Wen of Wei Cao Pi conquers Sun Wu in the south, and his troops arrive at Guangling. Facing the Yangtze River, he has to sigh: "Although Wei has thousands of martial cavalry, there is no use, and it is not possible to do it.

"   Note: Volume 70 of Zizhi Tongjian    Wei Ji Er    The following year, the Lord of Wei launched a large-scale attack on Wu again. Seeing the turbulent waves of the river, he sighed, "Alas! The sky is limited to the north and south."  [  Note: Volume 70 of Zizhi Tongjian    Wei Ji Er                                                                                                                                                                                                 

The Huai River and the Yangtze River play a dual role in the intersect and barrier. Gu Zuyu concluded: "Dividing the border from the north and the south is often the Yangtze River blocked by the Yangtze River." He also said: "The Jiangnan River is dangerous, and the one who guards the river is better than defending the Huai River. If the Huai River in the south is enough to resist the north, and if the Huai River in the north is not protected again." [  Note: Volume 19 of "Reading History Fangyu Ji" Volume 19 of Jiangnan 1]   If the defense of the Yangtze River is purely passive, then the Huai River has both the meaning of defense and active offensive. The south is against the north, in terms of defense, the defense of the Huai River can be used as a depth of the vast area of ​​Huai South; in terms of attack,

You can enter the Central Plains after leaving Huaibei. Most of the tributaries of the Huaihe River originate from Huaibei, especially Sishui. After a little digging, you can connect the Yellow River, so that the power in the south can be extended to the Yellow River Basin; while if you guard the Yangtze River alone, you will be broken into one place and you will be in your heart. Those who have protected the Jiangnan in the past dynasties have discussed this lip-dentist relationship between the Huaihe River and the Yangtze River, and the argument that you must first guard the Huaihe River first can also be seen everywhere. For example, Lu Zhi of the Southern Song Dynasty said, "The dangers of the Jianghuai River are the limits of the north and south. Since the establishment of the country in the south, he guarded the river to be a household and prepared the Huai River as a barrier." [   Note: The Jianghuai River's "Easy Defence in Southeast" in "The Properties of the Jianghuai River"]

The focus of the Yangtze River is on the mutual harmony between the upper and lower levels, and the focus of the Huai River is on the mutual harmony between the inner and outer levels.

Lu Zhi of the Southern Song Dynasty presented the Song court with "Energy of Defense in Southeast" and wrote three theories: "The Fundamental Theory of Jiankang", "Theory of Rivers Up and Down", and "Theory of Jianghuai's Outside and Internal Theory". It suggested: establish the capital Jiankang as the basis for the King of Xing; station troops in Jiangling, Xiangyang, Wuchang, and Jiujiang to consolidate the upstream and downstream trends; guard the river to govern the internal, prepare the Huai to govern the outside, and the Huai to govern the river and the inner river. In this way, the Central Plains can be restored.

Shandong and Jingxiang are like the two wings in the southeast, protecting the entire Jianghuai defense system. Shandong is enough to protect the upper reaches of Huai and Si, and Jingxiang is enough to protect the upper reaches of Jianghan. Previous people once said, "Those who strengthen the southeast must compete for the Jianghan; those who look at the Central Plains must obtain Huai and Si. If there is Jianghan but no Huai and Si, the country will be weak; if there is Huai and Si, but no Jianghan, the country will be in danger." [  Note: "Reading History and the Records of Jiangnan" Preface]  The north of Shandong to consolidate the upper reaches of Huai and Si, and the west of Jing and Xiang to consolidate the upper reaches of the Yangtze River are the best situation for those who control the southeast. .  .

(I) Yangtze River Defense Line

There are a series of important military cities along the Yangtze River in the south, guarding several key points of the Yangtze River. In ancient times, there were two places where the lower reaches of the Yangtze River were easy to cross the lower reaches of the Yangtze River, one was Caishi Ferry, and the other was Guazhou Ferry, which was divided into the upstream and downstream of Jiankang. The enemy in the north of the Yangtze River crossed the river and attacked Jiankang in these two places. Jiankang also strengthened the defense of these two ferries, and placed troops to guard them on the south bank of these two ferries, and established them as important towns, namely Jingkou (now Zhenjiang) and Caishi. The opposite of these two places is Guangling (now Yangzhou) and Liyang (now Hexian) to the west. The cavalry from the north goes south and often reaches Guangling in the east and Liyang in the west, so it is also established to guard them.

Jingkou is now Zhenjiang City, Jiangsu Province. Sun Quan first established the capital here, called Jingcheng, and moved the capital to Jianye, and established Jingkou Town. Since then, those who established the country in the southeast have all regarded Jingkou as the important town. During the Eastern Jin Dynasty, Xi Jian managed Jingkou to defeat the Su Jun rebellion, so he built it into Xiong Town, known as the Northern Prefecture, and together with the Western Prefecture Liyang and Nanzhou Gushu, guarding the capital Jiankang. Huan Wen was specialized in government affairs and regarded Jingkou as a thorn in his side. He once said that "Jingkou wine can be drunk and soldiers can be used." [  Note: Volume 1 of Zizhi Tongjian

Hundred and two hundred and two Jin Ji 24] His adviser Xi Chao met his intentions and implied that his father Xi Yin gave up Jingkou to Huan Wen. Xie Xuan defeated Fu Jian's army in the Former Qin Dynasty in Feishui, and relied mainly on the Northern Palace soldiers in Jingkou. Huan Xuan went east from Jingzhou, and the court relied on the Northern Palace soldiers to resist Huan Quan, but the Northern Palace general Liu Laozhi surrendered to Huan Xuan, and Huan Xuan then entered Jiankang. Huan Xuan served as the Jin, Liu Yu, Liu Yi and others to raise troops to rebel against Xuan in Jingkou, so as to destroy Xuan. After Liu Yu replaced the Jin Dynasty, he was in view of the war in Jingkou.

In the end of the Liu Song Dynasty, Jingkou's position was important, and Wang Seng was in charge of the capital. He was not allowed to live in the neighborhood of the royal family." [  Note: Volume 78 of the Book of Song Dynasty, Biography of Liu Yansun]   End of the Liu and Song dynasties, Jingkou's position was very important, whether in the war against the northern enemy or in the internal political struggle. At the end of the Liang Dynasty, Chen Baxian ruled Jingkou, Wang Sengbian guarded Jiankang, Chen Baxian attacked Wang Sengbian, and also attacked Jingkou, and finally established the Chen Dynasty to dynasty Liang. In the battle of the Sui Dynasty to destroy Chen, He

Ruobi took the lead in crossing the Yangtze River from Guazhou, captured Jingkou, and surrounded Jiankang with Han Qinhu, who crossed the river from Caishi. In the early Tang Dynasty, Li Zitong attacked Shen Faxing and also crossed the river from Guangling to take Jingkou. The Southern Song Dynasty was in the southeast, and the ministers were in charge of war and sent ministers to manage Jiankang. Jingkou used to draw the Central Plains. As Chen Liang once wrote to Emperor Xiaozong, saying: "Jingkou is connected to the three sides, and the river is crossing the river, and the river is thousands of miles away. Its power is roughly like a tiger coming out of the cave." [   Note: "Collection of Chen Liang" Zhonghua Book Company, Volume 1]

Caishi is the Caishiji today. It crosses the river opposite the Hengjiang River. Its land suddenly towards the center of the river. There is a relatively good crossing dock. It is where the Yangtze River is easy to cross the Yangtze River in ancient times. Qin Shihuang inspected the southeast and crossed the river from here. Sun's strategy took the east of the Yangtze River and crossed the river from here. Later, it was built into an important town. During the battle of the Western Jin Dynasty to destroy Wu, Wu Prime Minister Zhang Ti led his army to Caishi and crossed the river to fight against the Jin army. He was defeated. The troops above the Jin Dynasty rushed in and went straight to Jianye. In the first year of Yongjia (307), Chen Min raised an army based on Jianye, and Liu Ji, the governor of Yangzhou of Jin, crossed the river from Liyang to fight against it. In the Eastern Jin Dynasty, Su Jun raised an army based on Liyang and led him to lead him.

The army crossed the river from Hengjiang to pick quarry and forced Jiankang to the east. In the first year of Xiankang (335), Later Zhao Shihu led his army south and rode to Liyang. The Eastern Jin Dynasty suddenly increased the garrison of Caishi, Wuhu and Cihu to prepare for it. In the second year of Taiqing of Liang (548), Hou Jing raised an army to rebel against Liang, and went from Shouyang to Liyang. The prefect of Liyang, Zhuang Tieyi, surrendered to the city. He also suggested that Hou Jing say: "It is better to take advantage of this moment to quickly visit Jiankang, and the soldiers can be achieved without bloodshed. If the court Xu De was prepared, Xiao An from the inside and outside, he sent a thousand weak soldiers to directly occupy Caishi. Although the king had a million armors, he could not help." [   Note: Volume 161 of "Zizhi Tongjian"

Liang Ji 17  ]                                                                                                                                                                                                                                                          �

Volume 176 of Zhitongjian" Chen Jishi]    In the eighth year of Kaibao in the Northern Song Dynasty (975), Cao Bin led his army to attack the Southern Tang Dynasty, defeated the Southern Tang Dynasty's defenders in Caishi, occupied Caishi, and then set up a floating bridge in Caishi to connect with the Song army in Jiangbei. The Song army then advanced straight into the ground as if walking on flat ground. In the 31st year of Shaoxing in the Southern Song Dynasty (1161), the lord of the Jin Dynasty, Wanyan Liang, invaded the south and also tried to cross the river from Caishi, but was defeated by Yu Yunwen. In the 15th year of Zhizheng in the Yuan Dynasty (1355), Zhu Yuanzhang attacked Hezhou and prepared to attack Jiangnan. The army crossed the Hengjiang River and occupied Caishi, so he occupied Jiqing (now Nanjing) and created the BenQ.

Liyang is the current He County. When moving south from Huaixi to Jiankang, you must go through Yang. Shouchūn, south of Fengyang, Chaohu is the key to the rush; west of Chaohu, the terrain is complex, which is not conducive to the passage of the army; east of Chaohu, there are fewer hills and rivers, which is conducive to the passage of the army. Northern forces go south and often come out of this way. Liyang is the key to this. Gu Zuyu said: "Since the country was in the southeast, it has always been taking Liyang as the key; those who have something to do in Jiangnan have come from Shouyang, and seven out of ten people came from Liyang." [  Note: Volume 29 of "Reading History Fangyu Ji" 11 of Jiangnan]    Lu Zhi of the Southern Song Dynasty also said: "Liyang, Jiankang, is the gateway of Gushu. There have been no Liyang that has been able to rest in Jiangdong because of the fact that there are many Liyangs.

”  [   Note: Lu Zhi's "Southeast Defense Advantage" in Jianghuai's Outside and Internal Discussion]     Sun Ce occupied Jiangdong and crossed the river from Liyang. The Western Jin Dynasty destroyed Wu, and Wang Hun came out of Liyang and crossed the Hengjiang River. During the Eastern Jin Dynasty, Su Jun also crossed the Hengjiang River from Liyang and attacked Gushu and went down to Jiankang. Later Zhao Shihu plundered Huainan, and the cavalry arrived at Liyang. In the martial law of Jiangnan. At the end of Liang, Hou Jing rebelled from Shouyang and had Liyang. He then went out of Hengjiang to cross the quarrying river and then entered Jiankang. During the battle of the Sui Dynasty to destroy Chen, Han Qinhu, the general manager of Luzhou, went from Luzhou to Liyang, and crossed the quarrying river from Hengjiang to cross the quarrying river. The Song and Jin confronted each other, and the Jin soldiers went south, and they often arrived at Liyang. In the early Ming Dynasty, Zhu Yuanzhang took Jiangnan and crossed the river from Liyang to overcome the quarrying river and went down to Taiping (Gushu).

(II) Huaihe River Defense Line

There are also a series of important towns in the south on the Huaihe River line, which are linked to the intersection of the tributaries of the Huaihe River and the Huaihe River. In Huaixi, it is mainly Shouchūn (now Shou County) and Zhongli (now Fengyang), and in Huaidong, it is mainly Shanyang (now Huai'an) and Xuyi.

The main tributaries of the upper reaches of the Huai River are Yinghe and Wohe. The intersection of Yinghe and Huai River is Yingkou, and the intersection of Wohe and Huai River is Wokou. Shou chūn is opposite Yingkou, blocking the enemy from the Yinghe and Huai River; Zhongli is opposite Wokou, blocking the rush of Wohe River. When the north and south confrontation are confronting, Zhongli and Shou chūn are both important towns in Huaixi.

The main tributaries of the lower reaches of the Huai River are Si Shui, also known as Qinghe. In ancient times, Si Shui flowed southeast of Shandong and flowed into the Huai River near Huai'an. The mouth of the Huai River is called Sikou, or Qingkou, Huaikou. Huai and Si Shui Road have been the main transportation routes in the north and south since ancient times. Shanyang and Xuyi are nearby, controlling the way of the Si Shui direction. In this direction, if you take a more positive situation, you can also manage Pengcheng (now Xuzhou) to explore the north.

Shou chūn is the current Shou County. The Ying River, the main tributary of the Huai River, flows into the Huai River near it. Ying River is an important transportation line between the Central Plains and the Jianghuai River. The intersection of the Ying River and the Huai River is called Yingkou. Shou chūn is opposite Yingkou. Enemies coming from the Ying River or the upper reaches of the Huai River must pass Shou chūn. Gu Zuyu called Shou chūn "controlled Huai Ying, tied with Jiangtuo, and was the key hub of the northwest and shielded in the southeast." [  Note: Volume 21 of "Reading History and the Records of the Three Kingdoms"]  In addition, the Shou chūn area is part of the Huanghuai Plain. The soil is fertile, the irrigation is convenient, and it is suitable for farming. Therefore, its local area is sufficient to be a resource for war and defense.

At the end of the Warring States Period, after Chu lost the land of Yan and Ying, he moved east to Huainan, and once used Shou chūn as his capital. During the Western Han Dynasty, Shou chūn was the capital of the Kingdom of Huainan. The land of Huainan was strong and strong. After the Han court reduced the vassals, he was afraid and uneasy, so he planned to raise an army. Wu was suggested: "Skip Hengshan to attack Lujiang, have a ship to Xunyang, guard the city of Xiazhi, build the Pupu of Jiujiang, and break the mouth of Yuzhang, and guard the river and guard it to prohibit the southern county, protect Kuaiji in the east, and connect the Jinyue in the south, and rise to the Jianghuai between the Yangtze River and the strongest, which can prolong the life of the years." [  Note: Volume 45 of "Han Shu"]  At the end of the Eastern Han Dynasty, Yuan Shu occupied Shou chūn and the emperor was the rule. In the fourth year of Zhengshi of Cao Wei (243), Deng Ai visited the north and south of the Huai River, and visited Chen and Xiang east,

At the end of my life, the above proposal was to establish a policy, suggesting: "Assign 20,000 people in Huaibei and 30,000 people in Huainan, two of them are left to rest, and there are often 40,000 people. The fields are kept, and the annual harvest is always harvested, three times more than a hundred times. In this way, the amount of money is calculated to be divided into five million hu of military resources. In six or seven years, 30 million hu can be accumulated on the Huai River, which means that a hundred thousand hu can be eaten for five years. By this, the number of people who have been employed by Wu will never go." [  Note: Volume 28 of the Three Kingdoms, Biography of Deng Ai] Sima Yi, who was in charge, adopted the strategy and cultivated farms in the north and south of the Huai River, opened up rivers and canals to increase irrigation and transport water. Since then, every time there is something in the southeast, the army will travel to the Yangtze River and Huai River, and the food will be stored, but there is no water damage, laying the foundation for the destruction of Wu in the future of the Western Jin Dynasty.

During the Wei, Jin, Southern and Northern Dynasties, the north and south confronted each other between the Jianghuai River and Huai River, and the south and the south were in a hurry to fight for the north and south. Sima Rui first decided to Jiangdong, and Ying Zhan suggested: "Shou, the meeting of one side is not far away. It is advisable to choose a governor who has civil and military strategies. He is far away from the situation of turning the Heluo River and Luo River, and recently he is considered a vassal state of Xuyu. Sui gathered and dispersed, so people have a good support, and specialize in agricultural merits, so that things can be made in a certain way." [  Note: Volume 26 of "Jin Book" Food and Goods"]  The Eastern Jin Dynasty was based in Jiangdong, but still called for the recovery of the Central Plains. Therefore, it was a major town in Huaixi, and in terms of advancing, it could echo the situation of the Central Plains. Moreover, it was gathered by refugees between the two Huai Rivers and recruited comfort, which was of great significance. In the fourth year of Taihe of Jin (369), the governor of Yuzhou, Yuan Zhen, was appointed as a minister. Shou chūn surrendered to the Former Yan, and the Former Qin Dynasty sent troops to rescue at the same time. The Grand Sima Huanwen of Jin led his army to defeat the reinforcements of the Former Qin, and captured Shou chūn and recovered Shou chūn. At that time, Fu Tao followed Heng Wen to Shou Yang, and repeatedly rebelled in Huainan. Then he wrote the Zhenghuai Theory of "Zhenghuai" to talk about the importance of Shou chūn: "That Shouyang is to lead Jingru's profit in the south, and connect the wealth of the Three Wus in the east; to connect the Liang and Song Dynasty in the north, and the plain road is only 700; to support Chen Xu in the west, and the water and land are not inside; there are obstacles from the rivers and lakes outside, and there are solid Huai Fei inside. Longquan's ponds, thousands of hectares of good fields, Shu, and six tributes, and the profits are over the Man Yue." [  Note: Volume 92 of "Book of Jin" Fu Tao's Biography] Fu Jian attacked Jin, and the vanguard had already taken Shouyang, but in the Feishui near Shouyang, Xie Xuan led the Jin army to defeat the Former Qin army and recover Shouyang. After this defeat, the Former Qin Dynasty was suddenly defeated. The collapse. At the end of the Eastern Jin Dynasty, Liu Yu "exploded Henan, Suided Yu's land, cut off the west of the Yangzhou River, and north of the Dalei belonged to Yuzhou."  [  Note: Volume 14 of the Book of Jin, Geography, ]                                                                                                                                                                                                                       � Note: Volume 135 of Zizhi Tongjian, Qi Jiyi]    In the late Xiao Qi year, Pei Shuye, the governor of Yuzhou, surrendered to the Northern Wei Dynasty with Shouchūn. The Northern Wei sent troops to support him. Shouyang and Huainan entered the Northern Wei Dynasty. Liang took advantage of the civil turmoil in the Northern Wei Dynasty to recover Shouyang and Huainan. During the "Houjing Rebellion", the East and Western Wei took advantage of the Li Nan to advance south, and Shouyang and Huainan entered the Eastern Wei Dynasty. In the fifth year of Taijian in Chen (573), Wu Mingche made an expedition to restore Shouyang. Chen Lord issued an edict for it: "Shouchūn was the ancient capital, which was built with Huai, Ru, controls and steers the river and Luo, and those who got it were peaceful, which was called the key."  [  Note: Volume 9 of "Chen Shu" Biography of Wu Mingche]   After Wu Mingche's defeat, Shouyang and the entire Huainan were captured by the Northern Zhou Dynasty. The Chen people had to defend the river and the situation was extremely unfavorable.

During the Five Dynasties, Emperor Shizong of the Later Zhou Dynasty conquered the Southern Tang Dynasty and attacked Shouzhou for nearly three years but could not be defeated. Later, the Shouzhou garrison surrendered with hope of breaking up the support. Once Shouzhou surrendered, the prefectures in Jiangbei were popular one after another. When the Song and Jin confronted each other, the Jin soldiers went south to Jianghuai, and Shouzhou was always in extreme conflict. Lu Zhi said: "Huaixi, the shield of Jiankang, Shouchūn is also the origin of Huaixi. If Shouxi is lost, he will leave Hefei and occupy Liyang, and Jiankang will not be able to rest." [  Note: The Jianghuai External and Internal Theory of the Southeast Defense Advantages]

The Wohe River is another important transportation line between the Central Plains and the Jianghuai River. The intersection of the Wohe River and the Huai River is called Wokou. Fengyang faces Wokou, blocking the rush of Wohe River. When the north and south confronts, Fengyang and Shou chūn are both important towns in Huaixi. Fengyang was the Zhongli County during the Southern and Northern Dynasties. After the Liu Song Dynasty lost the Huaibei prefectures, he had to rely on the Huaihe River to defend. Zhongli was the main attacking direction from Xuluo. Every time the Northern Wei Dynasty went south, Zhongli was one of its main attack directions. At the end of the Liang Dynasty, Zhongli and Shou chūn entered the Eastern Wei. When the Song and Jin confronted each other, the Jin people established Liu Yu in the Central Plains and controlled Huai with China. In the sixth year of Shaoxing in the Song Dynasty (1136), Liu Yu invaded Huaixi and the court discussed

yù abandoned Huai and protected the river. The Privy Councilor Zhang Junli said in reverse, saying: "There are all garrisons in Huainan, so that the river will be blocked; the thieves were able to get Huainan, and they were transported by food and thought it was a family plan. Then the danger of the Yangtze River will be shared with the enemy, and the south of the Yangtze River will not be protected. Huainan is suitable for garrisoning Xuyi to block the upstream of the Qing River; Huainan is suitable for garrisoning Hao and Shou to block the Wo and Ying road." [   Note: Volume 117 of "Suo Zizhi Tongjian"] Haozhou is Fengyang. Hao and Shouzhou are respectively controlled by garrisoning Wo and Ying two garrisoning respectively, which is the key to guarding the Huai River. In the 1141 year of Shaoxing (1141), Zhang Jun, Liu Qi and Yang Yizhong's three generals were defeated in Haozhou, and the Song court decided to negotiate peace.

The main tributaries of the lower reaches of the Huai River are Si Shui, and Si Shui is also called Qinghe. In ancient times, Si Shui flowed southeast of Shandong, passed through Yanzhou, Jining, Xuzhou, and Suqian, and merged into the Huai River near Huai'an. The river channel in the lower reaches of the Huai River has undergone great changes, especially the Yellow River diverted, seized Bian, Si and other rivers and entered the sea. Therefore, the current Si Shui River is no longer the old appearance of the year. The mouth of Si Shui entering Huai River is called Sikou, which is also called Qingkou and Huaikou. The Huai Si Shui Road has been a major transportation route in the north and south since ancient times. King Jun of the Western Jin Dynasty attacked Wu, and Du Yu wrote a letter to encourage him to directly attack Jiankang to destroy Wu. However,

Later, "from the river to the Huai River, crossing Sibian River, going up the river, and returning to the capital, it is also a worldly matter." [  Note: Volume 81 of Zizhi Tongjian, Jin Ji3]    According to the route indicated in Du Yu's letter, the Wang Jun navy could travel directly from Jianye? It can be seen that the two rivers of Bian and Si are connected to the Yellow River through the Huai River. The two major water systems of the Yangtze River should be relatively early; Huan Wen and Liu Yu's northern expeditions all opened the Si River; Emperor Yang of Sui opened the Grand Canal and also used the two rivers of Bian and Si.

The main important towns in the lower reaches of the Huai River are Huai'an and Xuyi, which guard the Huai-Si River. Huai'an was Shanyang County during the Eastern Jin Dynasty, Chuzhou during the Sui and Tang Dynasties and Song Dynasties, and Huai'an during the Yuan, Ming and Qing Dynasties. During the Yuan, Ming and Qing Dynasties, Cao Pi, the Wei lord, personally led the navy army to enter the Huai River and went to Guangling, and the Zhou army went from Huai'an to the south. The Eastern Jin Dynasty and the Southern Dynasties all regarded Huai'an as the important town, and Zu Yue, Liu Wei, Xun Xian and others were to guard their land one after another. In the third year of Taiyuan in the Eastern Jin Dynasty (378), the Former Qin general Peng Chao suggested Fu Jian: "I would like to send more important generals to attack Zhucheng in Huainan to be a chess robbery.

The momentum, east and west, Danyang is not enough to settle."  [   Note: "Zizhi Tongjian" Volume 104  Jin Ji 16  ]   Fu Jian followed it and sent troops to attack Huaiyang and Xuyi. After the failure of the Northern Expedition in the 27th year of Yuanjia in the Liu Song Dynasty (450), the prefect of Shanyang Xiao Sengzhen all collected the people into the city, built dikes and accumulated water, and waited for the Wei soldiers to arrive, and broke the dikes and poured them into the city. The Wei army passed by Shanyang and did not dare to attack the city. During the Taishi period of the Liu Song Dynasty, the Northern Wei generalized Shanyang and the Pengcheng area became a base that forced Jianghuai in the south. The Southern Dynasty

The situation was already very unfavorable. When Wu Mingche of the Chen Dynasty attacked the northern expedition to siege Pengcheng, Zhou general Wang Gui advanced southward and attacked Qingkou, cutting off the Chen army's return route. Mingche was defeated. The Song Dynasty moved south and leaned on the Jianghuai River to block the southeast. Shanyang's status became important again. Wu Biaochen said: "Shanyang controls the land, but if it is lost, it will not be able to block the east of Huai." [Note: "Reading History's Fangyu Ji" Volume 22 Jiangnan 4] Xu Zongyan also said: "Shanyang must compete for the land north and south. If I get it, I can advance to Shandong; if the enemy gets it, I can gain it.

In this case, Huainan cannot be consolidated day and night."  [  Note: Volume 22 of "Reading History and the Records of Fangyu" Volume 22 of Jiangnan 4]   The Grand Canal Channel passed through Huaian, so both Yuan and Ming dynasties set up important officials and established troops to manage them. During the peasant uprising at the end of the Yuan Dynasty, Yuan general Dong Boxiao guarded Sizhou and suggested that the Yuan court increase the garrison of Huaian: "Huai'an is a place where the north and south are closed, and the Jianghuai is the main place. Once the land is lost, both Huaihuai will not be restored. It is urgent to rescue Huaian."  [  Note: Volume 188 of "History of Yuan Dynasty" Biography of Dong Boxiao]

Xuyi was an important town in Huaidong. Xuyi was once the capital of King Huai of Chu at the end of the Qin Dynasty. During the Eastern Jin Dynasty, Yao Xiang, a Qiang man, defeated Yin Hao's army in Huainan and entered Xuyi, but the Jin court could not control it. In the third year of Taiyuan in the Eastern Jin Dynasty (378), the generals of the Former Qin Dynasty captured Xuyi. It was not until the Battle of Feishui that the Eastern Jin Dynasty recovered Xuyi. During the Yixi period, the Jin court established Xuyi as a county, which was followed by Liu Song Dynasty. When the northern expedition failed (450), the prefect of Xuyi, Chen Pu, took Xuyi to the point of being located in the Great Wall, and then repaired the city and dredged the gods, accumulated the materials and valleys, and stored arrows and stones to prepare for the city guards. When the Northern Wei advanced south, Zai Duo of the county guards in the Huaihe River area abandoned the city and fled. Chen Pu held on to Xuyi; after the general Zang Zhijun of the auxiliary state collapsed, he also led the remaining troops into Xuyi. The two of them worked together to defend Xuyi. The Wei lord Tuoba Tao personally commanded the attack on Xuyi for more than 30 times on the way from Guabu to retreat north, but failed to break the city. He had to burn the siege equipment and left, showing that Xuyi was indeed an important town in the Huaidong area. Shortly after the Northern Wei retreated, Liu Yilong immediately appointed his younger brother Liu Yigong as the governor of Southern Yanzhou, General of Cavalry, and general of the military affairs of the thirteen prefectures. He moved to Xuyi to revitalize the broken defense system in the Jianghuai area. The following year, Liu Song merged Yanzhou to southern Xuzhou, and appointed another Huainan governor, stationed in Xuyi, and founded military farms, which should be connected to the near and far.

Pengcheng is the foundation of Huaibei. Many waters near Pengcheng gather. Si River flows from near Pengcheng. Si River goes northwest and opens Juye and enters the Yellow River. During the southward flow, it gathers Bian River, Jushui and other rivers. Before the Sui Dynasty, the Bian River flows into Si River near Pengcheng. After Liu Yu destroyed the Later Qin Dynasty, the Bian River returned south. The boat army entered the river from Wei, opened the Bian Canal, entered Bian from the River, and then returned to Pengcheng. Ju? The water flows into Si River near Pizhou (now Pi County). Ju? The water flows into the mouth of Si River is called Ju? Qingkou. Chen You's attack on Pengcheng was not good, and he was defeated at Ju? Qingkou.

Pengcheng can be said to be a place of four battles and must be fought for by military strategists of all dynasties. Pengcheng was the capital of Xiang Yu, the overlords of the Western Chu during the Chu-Han period. At the end of the Eastern Han Dynasty, Xuzhou was a place of dispute. Tao Qian, Liu Bei, Lu Bu, and Cao cāo all fought for Xuzhou. Sun Quan once wanted to capture Xuzhou, but Lu Meng used Xuzhou as "the terrain was connected by the land and the cavalry was roaming with it", and the land was close to Xu Luo. Although he captured it, Cao cāo must fight with all his strength. It would be better to attack Jingzhou and occupy the Yangtze River. [  Note: "Zizhi Tongjian" Volume 63, Han Ji 55]

The status of Pengcheng is even more important under the confrontation between the north and the south. Among the several levels of the Jianghuai defense line, the Yangtze River wings cover the south of the Yangtze River, the Huainan wings cover the Yangtze River, and the Huainan wings cover the north and the north and the south. Pengcheng is actually the foundation. Pengcheng is close to the Central Plains and interferes between the north and the south. It has convenient water and land transportation, which can be used as a resource for war defense. Su Shi said in the status of Pengcheng: "Xuzhou is the key to the north and south, and is the safety of the counties and towns in Jingdong. Its land is surrounded by mountains on three sides, and it is only a few hundred miles west of the river. It travels to Liang and Song west, so that the Chu people can open and extend the enemy. It is really like building water from the house." [  Note: "Reading History's Fangyu Ji" Volume 29, Jiangnan Eleven"]

In the third year of Long'an in the Eastern Jin Dynasty (399), the Northern Wei destroyed the Later Yan. Murong De of Later Yan led his remaining troops to the south and planned to seize one side first. As a base, his subordinate Zhang Hua suggested to capture Pengcheng. Shangshu Pan Cong tried to declare Pengcheng a major town in Jin, and it was difficult to fight. He said: "Pengcheng is vast and sparse in the land, and the plain and barbarians are not easy to take. Moreover, the old town of Jin is not easy to take, and it is close to the Yangtze River and Huai River, with many water in summer and autumn. Those who fight on boats are the strengths of the Wu people and my weaknesses. It is better to take Guangguo and take over it." [  Note: "Zizhi Tongjian" Volume 111, Jin Ji 33] Pan Cong saw the significance of Pengcheng to the Eastern Jin Dynasty and came to the conclusion that "not easy to take" was. Liu Yu and Liu Yilong both used Pengcheng as the base for the Northern Expedition. Liu Yu's Northern Expedition of Later Qin , that is, Pengcheng was used as its base for advancement; Liu Yu successively promoted the titles of Song Gong and Song King, and Pengcheng was the capital of his fiefdom. Liu Song and Yuanjia Northern Expedition, and Pengcheng was also the base for advancement. During the Northern Expedition in the seventh year of Yuanjia, Changsha King Liu Yixin went out to seize Pengcheng to support the army. On the eve of the northern expedition in the 27th year of Yuanjia, Wang Xuanmo was the prefect of Pengcheng and advanced to the Central Plains. The above statement said: "Pengcheng must be both water and land, please use the prince to pacify Linzhou." [  Note: "Zizhi Tongjian" Volume 125  Song Jiqi] Liu Yilong then appointed his third son Liu Jun as the governor of Xuzhou, and was in charge of Pengcheng, preparing for the Northern Expedition. After the failure of this Northern Expedition, Liu Jun and Jiangxia King Liu Yigong defended Pengcheng, and the Northern Wei went south and did not dare to attack Pengcheng lightly.

During the civil strife during the Taishi period of the Liu Song Dynasty, Emperor Ming of Song and Ming Dynasty repaired the empress, which caused Xue An, the governor of Xuzhou, to surrender to the Northern Wei Dynasty with Pengcheng. Liu Song tried to retake Pengcheng but failed. After that, the Northern Wei actively operated Pengcheng as a base for the south to force Jianghuai. In the early Northern Wei Dynasty, the chief general Wei Yuan submitted a letter to manage Pengcheng: "The thieves in Pengcheng must not accumulate grain and force to defend it, and they cannot be solid. If they store grain and guard the grain, even if Liu Yu and his disciples move, they dare not peek at the land of Huaibei. This is a natural trend." [  Note: Volume 50 of "Book of Wei"]   In the fourth year of Taihe of the Northern Wei Dynasty, Xue Huzi, the governor of Xuzhou of the Northern Wei Dynasty, said: "The country must first accumulate grain and store the grain and Pengcheng first. Only when the troops in the town are not reduced, the silk of the capital is twelve, and the cost is not accurate. Before the generations, they cannot avoid hunger and cold

, Public and private expenses were damaged. Today, Xuzhou has more than 100,000 hectares of fertile land, fertile land and fertile water and land. Qing and Bian were flowing, which was enough to irrigate. If you use soldiers to sell oxen, you can get ten thousand heads, and you can set up military farms. In one year, you can give official food. Half of the soldiers are breeding, and the rest of the soldiers are stationed and farmed and defended. You might as well defend the border. The harvest of a year is more than ten times the silk, and temporarily farmed, and it is enough to fill several years of food. Later, the military funds are stored in the public treasury. After the five years, the grain and silk are overflowing. It is not only that the garrison soldiers are abundant, but they can also swallow the enemy." [   Note: "Zizhi Tongjian" Volume 135 Qi Jiyi]     By the Chen Dynasty, Wu Mingche took advantage of the battle between the Northern Zhou and the Northern Qi Dynasty to fight against Huainan, and tried to fight for Huainan and recover Pengcheng, but when he besieged Pengcheng, he was defeated and captured. The last chance of the Southern Dynasty's rule of Huainan was also lost.

During the separatist rule of the vassal states in the Tang Dynasty, Li Zhengji, the governor of Ziqing, sent troops to block the Yongqiao Bridge in Xuzhou (now Beifuliji, Su County, Anhui), and the Wokou. The road to transport north and south was cut off for a while. More than a thousand ships were shipped in the Jianghuai River were not daring to enter. Li Mi suggested that Emperor Dezong of Tang said: "The Jianghuai River transport uses the Yongqiao Bridge as the throat. If Xuzhou is lost, it is a loss of Jianghuai. What is the national use? It is advisable to build a heavy town in Xuzhou to make the transportation roads always open, so that Jianghuai'an is the same." [  Note: Volume 29 of "Reading History and the Etiquette" Volume 29 of Jiangnan Eleven]

Pizhou (now Pi County) can be regarded as a supplement to Xuzhou's status. Pizhou is also on the Huai-Si River Transport Line, close to Qi and Lu in the north and blocking Jianghuai River in the south, which is a major obstacle for water and land transportation in the north and south. From Huai'an, from Sikou to Si River, go up against Si River, and go up to Pizhou, from Pizhou to northwest along Si River, you can go to Pengcheng and go to Central Plains; from Pizhou to northeast, facing the Yishui River Valley, you can go to Shandong. Pizhou and Huaian are both important links between Huaibei and Huainan.

Contact. The south fights Huaibei and the north fights Huainan. The capital must fight for Pizhou. Liu Yu attacked Nanyan in the north. After the Zhou army entered Si from Huai to Xiapi (now Pi County), he left ships to walk. After destroying Nanyan, he also "staying in Xiapi, running the Ministry and Yong"; Lu Xun went east to Jiankang, Liu Yu returned to the army, and his troops arrived in Xiapi, carrying baggage, and led the Reebatic cavalry to return to Jiankang. During the Taishi period of the Liu Song Dynasty, Xue An, the governor of Xuzhou, surrendered to the Northern Wei Dynasty with Pengcheng

. Wei Yuan of the Northern Wei Dynasty operated Pengcheng and once submitted a letter to ask for a visit to Xia Pi, Huaiyang and other places to defeat the Song army: "If the Song people go to Pengcheng, they must go from Qing Si to Suyu and go to Xia Pi; when they go to Qingzhou, they also go from Xia Pi to Yishui and pass through Dong'an. These numbers are all the key points of the Song people's use of the army. Now if they first set Xia Pi, settle Suyu, settle Huaiyang, and guard Dong'an, then Qing and Ji towns can conquer themselves without attacking." [  Note: Volume 50 of "Book of Wei" Biography of Wei Yuan]

Shen Youzhi advanced north along the Si River and tried to recover Pengcheng. Qing Jukou near Xia Pi was defeated by the Northern Wei, and the Huaibei prefectures could not be asked again. Chen took advantage of the civil unrest in the north to send Wu Ming to the north, and the Xia Pi area became the key point of the competition. At the beginning of the Five Dynasties, Huainan ruled and fought against the Central Plains, Pi and Xu areas to control Huai and Si, which was the key point of the competition. Zhu Wen fought for Pi, Xu and blocked Yang Xingmi, while Later Zhou took Pi, Xu and forced the Southern Tang.

This is the general situation of the Jianghuai defense system in the southeast region. Generally speaking, it can be divided into several levels: the Yangtze River line can be used as a level, on this line, with important towns such as Jingkou, Guangling, Gushu, and Liyang to protect the south of the Yangtze River; the Yangtze River can be used as a level, with important towns such as Shouyang, Zhongli, Shanyang, and Xuyi to protect the south of the Huai River; the Huai River can be used as a level, with important towns such as Pengcheng and Pizhou to protect the north of the Huai River.

These levels basically show the offensive and defensive situation shown by the north and south as their forces grow. When the south is strong, they can move forward north of the Huaihe River and advance to the Central Plains; when the south is weak, they often retreat to the Yangtze River and defend passively; when the north and south are evenly matched, they often use the Huaihe River line as the frontline for confrontation.

3. The Northern Expedition in the South

(I) Political issues of the Northern Expedition

From the Eastern Jin Dynasty to the Southern Song Dynasty, the southeast regime under the confrontation between the north and the south, held many northern expeditions. For example, the Zuti Northern Expedition (320 years), Chu Qi Northern Expedition (349 years), Yin Hao Northern Expedition (353 years), Heng Wen Northern Expedition (354 years, 356 years, 369 years), Xie Wan Northern Expedition (359 years), Xie Xuan Northern Expedition (384 years), Liu Yu Northern Expedition (400 years, 416 years), Liu Song Yuanjia Northern Expedition (430 years, 450 years, 452 years). Xiao Yan Northern Expedition (505 years), Wu Mingche Northern Expedition (573 years, 577 years), Zhang Jun Northern Expedition (1136 years), Yue Fei Northern Expedition (1140 years), Duanping Northern Expedition (1234 years), etc. From these frequently launched northern expeditions, some political problems can be deducted.

For the southeast regime under the confrontation between the north and the south, the Northern Expedition was always a banner, the flag that could be used to win people's hearts and integrate southern society.

Since most of the Southeast regimes are house-moving regimes, after northern ethnic minorities occupy the northern region, most of them can integrate southern society and unify half of the southern part of the Yangtze River. In the process of integrating southern society, the Northern Expedition and the recovery of the Central Plains are usually a banner that can win people's hearts.

In the Eastern Jin Dynasty, when the Southern Song Dynasty moved south, the north was occupied by ethnic minorities, the Central Plains were turbulent, the people were displaced, and people had no determination. The regimes that moved south had to clean up the situation and stabilize the people's hearts, relying on the identity of the preserver of Central Plains culture and the upright in traditional Chinese politics. But they all cleaned up the situation in a special context. Before the Eastern Jin Dynasty, the Southern Song Dynasty moved south, the Western Jin Dynasty and the Northern Song Dynasty were all destroyed by the northern ethnic minority regime. Sima Rui, the founder of the Eastern Jin Dynasty, and Zhao Gou, the founder of the Southern Song Dynasty, all rebuilt the country as a royal family and vassal king. This means that the regime that moved south to the southeast was not the original migration of the Central Plains regime. In this way, the newly established regimes would come out to integrate the social structure and social order that had been impacted and fragmented. The identity of his own regime as a "right" and a preserver of Central Plains culture should be emphasized.

At this time, the Northern Expedition to the Central Plains and the recovery of the old border can be used as a very useful banner. This banner can show the internal connection between the regime established by itself and the Central Plains regime. This point is of great significance to maintaining people's hearts and integrating internally. In other words, the banner of expedition to the Central Plains at this time is even more politically significant to the Jiangnan regime itself.

Indeed, the Northern Expedition to the Central Plains, expel the Hu people, recover the old borders, and return to their hometowns is very appealing to boost the hearts of the people in society. This is also a magical resource that the Northern Expedition can use. When Wang Dao crossed the river and cried in Xinting, "When we work together to fight the royal family and recover the Shenzhou, why should we become a prisoner of Chu cry?" [  Note: Volume 65 of "Book of Jin" Biography of Wang Dao"] How inspiring! Yue Fei's grand statement "ambition of eating the meat of the barbarians in hunger and drinking the blood of the Huns with a smile" is so passionate!

However, in history, although the southeast regime launched many Northern Expeditions under the confrontation between the north and the south, there were very few truly thorough and truly successful Northern Expeditions. If the Northern Expedition was only a banner to win people's hearts and integrate society, then the degree of social integration would in turn affect the achievements of the Northern Expedition itself. Only a society with relatively successful integration can aggregate a relatively powerful force; on the contrary, if social integration is not enough, powerful social forces cannot be gathered, and there will be no successful and more thorough Northern Expedition.

In the early Eastern Jin Dynasty, the imperial power fell, and the aristocratic politics were typical. The Wang, Yu, Huan, Xie and other major clans successively took charge of the government affairs, and several major clans restrained and maintained each other, thus maintaining this situation of multiple political developments. This situation hindered the comprehensive establishment of the feudal ruling order; it also hindered the comprehensive integration of the Jiangnan society. Therefore, the Northern Expeditions in the early Eastern Jin Dynasty, such as Zu Ti, Chu, Yin Hao, Xie Wan, and Xie Xuan during the Northern Expedition, the degree of integration of southern society was far from enough, and there were many factors that restricted the Northern Expedition, so great achievements were not achieved.

Zu Ti's northern expedition, the Jin court did not give substantial support. When Zu Ti had just laid the foundation in Henan, the Jin court sent Dai Yuan to control it. Zu Ti thought that he had "cut down the thorns and harvested the land of Henan, and (Dai) Yuan was graceful, and once he came to govern it, he was very disappointed. He also heard that Wang Dun and Liu (Wei) and Diao (Xie) had a slight ties, and would have difficulties. He knew that his great achievements would not be fulfilled, and he was grateful to have an illness." [Note: "Zizhi Tongjian" Volume 91, Jin Ji 13] No

After a long time of illness, all the previous efforts of the Northern Expedition were wasted. Chu Qi's Northern Expedition "all the court and the country thought that the Central Plains could be restored", while Cai Mo, a Guanglu official, said alone: ​​'Hu Miecheng was the Daqing, but he may even cause more worries to the court.'"  [   Note: "Zizhi Tongjian" Volume 98, Jin Ji Twenty]   The intentions and contradictions of each other at that time were not analyzed in a few words, but the above historical facts are enough to show that Chu Qi's Northern Expedition did not receive widespread support from Jiangdong society.

Sometimes, the Northern Expedition even became a tool for the power struggle of the aristocratic clans. For example, Yin Hao's Northern Expedition was like this. Yin Hao's Northern Expedition was largely a motion by the Jin court to curb Hengwen's Northern Expedition. Moreover, during Yin Hao's Northern Expedition, Wang Xizhi, who was born in the highest sect in Jiangzuo, once wrote a letter to Yin Hao: "Now the army is broken outside and the capital is exhausted inside and the ambition to protect Huai is not restored. It is better to return to the Yangtze River and supervise the generals to restore the old towns. From outside the Yangtze River, they are just detained." [  Note: "Zizhi Tongjian" Volume 99, Jin Ji 21, Jin Ji]   Don't agree with the Northern Expedition. After Yin Hao's Northern Expedition failed, Huan Wen took the opportunity to counterattack, thus taking the qualifications for the Northern Expedition for himself, and also holding the military and political power of the Eastern Jin Dynasty in his own hands.
To be continued...