Chapter 11 4. Xijian and the management of Jingkou

As discussed above, Xi Jian was able to deny Tao Kan and Yu Liang's plot to dethrone Wang Dao mainly because he occupied Jingkou as the governor of Xuzhou and played a pivotal role in Jiankang.It is a historical process that Jingkou became an important town in the Eastern Jin Dynasty. There are many reasons, not just for expediency considerations, nor is it achieved overnight.The formation of an important town in Jingkou originated in Xijian. The territory of Xuzhou is called "Haidai and Huaihe" in "Yu Gong".Xuzhou, one of the thirteen prefectures in the Western Han Dynasty, is roughly in this area.At the beginning of Jiang Zuo Liu’s residence, the territory of Xuzhou moved to the south, according to Huainan and north to Jiangbei. In the north of the Yangtze River.Xi Jian succeeded Liu Xia as governor of Xuzhou and governed Guangling.

In "Xi Jian Biography", Su Jun was in chaos and fell into Taicheng. Xi Jian sent human roads from Guangling to Jiangzhou. Yueyi cut off the grain transportation of the thieves. Then Jingkou was quieted down, and the walls were cleared to wait for the thieves. The thieves would not attack the city, and the wilderness would have nothing to plunder. Once the east road is cut off, the food transportation will be cut off by itself, and within a hundred days, it will collapse by itself." Wen Wen Qiao took it for granted.Xi Jian initiated the proposal of "Tranquilization of Jingkou", which was originally aimed at Su Jun's plot to rely on the Three Wus since he crossed the river from Liyang, and his army had no rear supply. An important town of health and safety.

At this time, Xi Jian was in a special situation.With the merits of diverting civilian commanders to Ping Wangdun, he was able to serve as the governor of Xu, Yan, and Qingzhou's military affairs, the governor of Zhuzhou (later Xuzhou), and the false festival, and he was among the ministers of the Ming Dynasty's posthumous edict to assist the government.However, because he had a different view of Wang Dun from Wang Dao, he had a sharp conflict with Wang Dao on the issue of Zhou Zha donating officials.Moreover, Xi Jian's status as a refugee commander is the same as that of Zu Yue and Su Jun, so it is rare to see Yu Liang who is trusted in the ruling, and he has no chance to be the center.In November of the second year of Xianhe, Zu Yue and Su Jun raised troops at the beginning. Yu Liang was worried that the whole situation would be chaotic and the situation was out of control, so he was not allowed to send troops to serve the king everywhere. "Shi Shuo Xin Yu Rong Zhi" quotes "Jin Zhong Xing Shu": "Wen Qiao and the three Wu wanted to raise troops to defend the emperor's house, but Liang refused to listen, and the order said: "Those who raise troops indiscriminately will be punished." Going to the disaster, "invaders from the north of the edict are not allowed." But at the same time or later, Yutan was ordered to supervise the military affairs of the three counties of Wu, Jinling, Xuancheng, and Yixing; Yu Xuancheng.Regardless of the prohibition of book making, Wen Qiao went east from Wuchang as early as one month before Su Jun Jijiang, that is, the first month of the third year of Xianhe (328), and marched in Xunyang, claiming to join Jiankang.Only Xi Jian is different. He is careful and dare not act rashly. He must wait for Su Jun to join the river, Taicheng to fall, Yu Liang to flee, and Tao Kan to go east. He had no choice but to punish the white horse and swear to the three armies to show his allegiance to the Eastern Jin Dynasty. Then, there was the above-mentioned suggestion to Wen Qiao to "tranquilize Jingkou".Moreover, he had to start from Jijiang in Guangling after he was appointed by Tao Kan to supervise the eight counties of Yangzhou. After Jijiang, he could not guard it according to Jingkou.These circumstances show that Xi Jian knows how to deal with himself in the Sujun Rebellion is a sensitive issue, and he must be cautious and not specialize in it, otherwise he will give others a handle.

The combined army of Tao, Wen and Yu, with Tao Kan as the leader, went down the river in May of the third year of Xianhe and stationed at Chapu and Caizhou at the mouth of the Qinhuai River in the west of Jiankang City.The white stone base built by Xi Jian's army was also handed over to Yu Liang's army for garrison.Xi Jian focused on the east. Wang Shu's Zhedong Army and Yutan's Zhexi Army were all under the control of Xi Jian.Su Jun sent generals Guan Shang, Zhang Jian and others to plunder the Three Wus, and then sent people out of the river to plunder the east of Jingkou.In this way, when Tao Kan's coalition forces and Su Jun's rebels were stalemate near Jiankang, the eastern battlefield from the south of Jingkou to Sanwu was formed, so Xijian was able to gradually realize his "quiet town Jingkou" to cut off Sujun East Road the plan of.

The formation of the eastern battlefield is closely related to the strategic position of the Sanwu area in Jiangzuo, and the strategic position of the Sanwu area has historical and geographical reasons, which need to be briefly reviewed. After the Western Jin Dynasty destroyed Sun and Wu, Sanwu was a place of "difficult security and easy movement".The Western Jin Dynasty guarded Jiangbiao with soldiers from the six states in the southeast, lest something would happen to the Three Wus.Wu Shi was discriminated against in Luoyang, which also increased Wu people's lack of self-confidence.Later, Wang Dao assisted Sima Rui, the king of Langya, to coordinate the interests of the old overseas Chinese gentry, so that most of the Sanwu gentry gradually entered the ruling group of the Eastern Jin Dynasty, instead of becoming a political force independent of the overseas Chinese gentry for a long time.In the various political events that occurred after Jiang Zuo, the Sanwu gentry was often divided into two parts, and the two groups were combined with the internal struggle of the overseas Chinese gentry.This was the case with Jiangzuo's several rebellions.In the first year of Jianxing (313), Wu Xing and Zhou Qi conspired against Sima Rui, and his accomplice was Zhendong Jijiu Donglai Wang Hui.In the first year of Yongchang (322), Wang Dun rebelled, Wu Xing and Shen Chong raised troops to respond, and Qian Feng of the same county was Wang Dun's mastermind.In Wang Dun's invitation to punish Liu Kuishu, he complained that Kui "reverted to the same name and took out all the guests". The "generally taken" should be the tenants of the powerful landlords from the Jiangnan gentry, because the tenants of the gentry with the surname of overseas Chinese are not "" Old name" can be checked.Since Wang Dun fought for the interests of the Southern scholars, there were Southern scholars Shen Chong and Qian Feng who supported Wang Dun.On the other hand, there were more Nanshi on the side of the Eastern Jin court. "Book of Jin" Volume 76 "Biography of Yu Tan": "Wang Han, Qian Feng and others attacked the capital, and Tan then recruited clan members and county surnames in this county (Kuiji Yuyao) to form an uprising army, numbering in the tens of thousands. "Kong Dan also raised troops in Kuaiji.This is evidence that Nanshi used force to support the Sima regime.In short, when the Eastern Jin court had something to do, it often affected the Three Wus; in the civil war in Jiankang, the Three Wus would appear on the eastern battlefield. "Tongjian" in the second year of Taining (324) Shen Chong Sima Gu Yang said that Shen Chong had the words "combining the power of the Eastern and Western armies", and Hu's annotation said: "The Eastern Army is called Shen Chongjun (the case originated from Wu Xing), and the Western Army is called Shen Chongjun. The army is also called Wang Han, Qian Feng and other troops (the case is near Jiankang)." The rebel army had the Eastern and Western armies, and the Eastern Jin official army also had the Eastern and Western armies.

In this context, Su Jun rose into chaos, and Jiangzuo quickly formed two battlefields called the East and West Army.In the eastern counties and counties, on the one hand, some people secretly descended on Su Jun to oppose the Eastern Jin court, as the "Wang Shu Biography" said, "Linhai and Xin'an Zhushan counties also responded to the thieves"; Crusade against Su Jun and resist Su Jun's coming from the east. "Book of Jin" Volume 77 "Biography of Cai Mo": "Su Jun rebelled, and Yu Bing, the domestic history of Wu, went to Kuaiji. [Jun] took Cai Mo as the domestic history of Wu. Since Mo arrived, he shared with Zhang Kai, Gu Zhong, Gu Yang, etc. Rebels, welcome the ice and return to the county." The rise of Wu Guoyi's army was mainly due to the brothers Gu Zhong and Gu Yang. "Book of Jin" Volume 76 "Biography of Gu Zhong": "Su Jun rebelled, the king's division was defeated, and the crowd returned to Wu, secretly trying to do righteous deeds....The former Linjiang general Zhang Wei retreated his troops to Wu for Jun, and sent people Yu Chan, He followed it. The crowd sent Langzhong Xu Ji to tell Mo, saying: "The crowd has joined forces with the family, and they will work hard when the time comes...'".At the same time, it is said that Fan Ming, a native of Linping, "leads a party of five hundred people", and together with Gu Zhong and other troops, four thousand people, attacked Su Jun's general Zhang Jian.The Danyang volunteers were gathered by Zhang Kai and Tao Hui. "Book of Jin" Volume 76 "Biography of Zhang Kai": Zhang Kai's grandson, Wu Zhang Zhao's great-grandson, lived in Danyang for generations, so he was born in Danyang.Su Jun, according to Jiankang, "envoy Kai to supervise the Eastern Army with the power of restraint".Zhang Kai not only organized the Wu Guoyi army with Gu Zhong brothers, but also supervised the Danyang volunteer army with Tao Hui, and used rice grains to help Xi Jian's army. "Book of Jin" Volume 78 "Tao Hui Zhuan": Tao Hui, a native of Danyang.Su Jun raised an army, "The king's division was defeated, and returned to the county to collect volunteers, and gained more than a thousand soldiers, and formed an infantry army. Together with Tao Kan, Wen Qiao and others, they attacked Jun with all strength, and don't break (jun general) Han Huang. "Wu Xingyi's soldiers were gathered by the prefect Yutan, and Yutan's family sent them as soldiers.

In the "Biography of Zhang Kai" quoted above, Zhang Kai was ordered by Su Jun to "supervise the Eastern Army". This Eastern Army probably refers to the original county soldiers in the eastern counties. "Book of Jin" Volume 76 "Biography of Wang Shu": "Jun Wenshu and others rose up, and they pardoned Yu Liang's younger brothers to please the Eastern Army."Both of them were troops in the eastern battlefield of the Eastern Jin Dynasty. Due to the rise of rebels in the eastern counties, Tao Kan used Wang Shu to supervise the military forces in eastern Zhejiang, and Yu Tan supervised the military forces in western Zhejiang.

The existence of the eastern battlefield in the Jiangzuo civil war shows that Nanshi was not only easy to recruit tribal soldiers in his hometown, but also had extensive political influence.If the Eastern Jin Dynasty can firmly control the Three Wus, the power of the Southern Scholars can be used by the Eastern Jin court, and the Three Wus can become the strategic rear of the Eastern Jin Dynasty. This is an extremely important factor for the consolidation of Jiankang.Therefore, Xi Jian supervised the eight counties in the southeast, not only for the needs of Su Jun, but also for the long-term strategic needs of the Eastern Jin Dynasty.

Sanwu became the strategic rear of the Eastern Jin Dynasty, and there was also an economic reason. This was the food supply in Jiankang, and the supplies for the troops on both sides of the Yangtze River below Jiankang had to be paid to Sanwu. "Yudi Jisheng" Volume 7 "Dingmao Port" notes "Yudizhi": "Jin and Yuan emperors mourned the town of Guangling, transported grain out of Beijing, and the water was dry. Please set up a dai. Dingmao made it possible, because he thought Name." The case of Guangling, Sima Zhong Town, Langxie King of the Eastern Jin Dynasty, was opened from June to October in the first year of Jianwu (317), and Dingmaodai was opened in this year. Today, there is Dingmao Bridge along the canal in the southeastern suburb of Zhenjiang City. It should be Guding Where Maodai is located.Guangling military rations, produced by Lai Sanwu, were transported through the north exit of the Canal to Beijing.When Su Jun was in chaos, the water transportation in the south of the Yangtze River was cut off, so according to Xi Jian of Guangling, "the city is lonely and grain is exhausted"; and after Xi Jian crossed the river, the army was in Jingkou, so he had to temporarily look up to Zhang Kai to supply rice grain from Danyang and Jinling nearby.Su Jun succeeded in harassing the three Wu, and the grain was relatively sufficient, so he was able to supply the Zuyue of Yuzhou with Mi Wanhu.Based on these circumstances, Xi Jian suggested that a fortress should be erected in the Qu'a area to cut off the grain transportation of Su Jun and the Three Wus.It can be seen that the Sanwu rice valley is the material basis for the war on which the two warring parties rely.

The south of the Yangtze River, from southern Jiangsu to eastern Zhejiang, is a land of grain production today.But in the Eastern Jin Dynasty, Danyang and Jinling were still very barren, and the grain-producing areas were in the Sanwu to the south.The place with the greatest development potential in Sanwu is Kuaiji, which is the heart of Sanwu.According to "Three Kingdoms · Wu Zhi · Zhongli Mu Biography", the paddy field in Yongxing (now Xiaoshan, Zhejiang) in Kuaiji had as much as three obliques per mu. "Book of Jin" Volume 77 "Zhuge Hui Biography" resumed as the prefect of Kuaiji, and Emperor Jin Yuan said: "Today's Kuaiji, in the past in Guanzhong, there is enough food and soldiers to be good guards." Kuaiji has this condition, so Su Jun On the eve of the rebellion, Wang Daomou recruited foreign aid, and his younger brother Wang Shu was appointed as the internal history of Kuaiji; while Su Jun raised his army, he had a plan to kidnap Emperor Cheng and go east to Kuaiji for a long-term plan;

Because Kuaiji has superior economic conditions and is relatively safe in the situation of confrontation between the North and the South, after the Cheng and Kang of the Eastern Jin Dynasty, overseas Chinese gentry such as Wang, Xie, Xi, and Cai rushed here to buy land and manage mountain residences. Refuge here, wait for time to come out. "Book of Songs" Volume 93 "Hermitage · Wang Hongzhi Biography" contains Xie Lingyun and Luling Wang Yizhen's note saying: "The meeting place is rich in mountains and rivers, so Jiangzuo Jiadun lived there. , or regaining talent is a matter of time, but if you don’t get it, follow your ambition..." In this way, Kuaiji has a special political status, and the sources of the powerful and noble figures who live in Kuaiji are extremely influential politically. In addition to these functions, Kuaiji County also has great military importance.According to Wu Tingxie's "Chronology of Fangzhen in the Eastern Jin Dynasty Preface", Fangzhen in the Eastern Jin Dynasty, Yangben Jidian, Jingdi is divided into Shaanxi, Xu is called Beifu, and Yu is called Xifan.Jiang, Yan, Yong, and Liang are also known as Xiongju, and Yi, Ning, Jiao, and Guang are Bianji.Although these prefectures are different in importance, they are all guarded by governors and governors. They were called "military prefectures" at that time.Outside of Junzhou, the only one who can be listed as a town by the status of a county is the post of internal historian of Kuaiji.Wu Tingxie said: "The internal history of Kuaiji is the governor of the five prefectures, and it is also the town." The five counties are Kuaiji (now Shaoxing), Linhai (now Linhai), Dongyang (now Jinhua), and Yongjia (now Wenzhou). , Xin'an (government today Chun'an). Kuaiji was originally a county, and in December of the second year of Xianhe Emperor Cheng (327), when Su Jun started his army, the Eastern Jin Dynasty moved Yuan Emperor's son Langxie Wang Yu to be the king of Kuaiji, and Kuaiji was changed from a county to a country.Roughly speaking, in the Eastern Jin Dynasty, whenever there was an event in the East, the internal history of the Jiji judged the degree of prestige of the incumbent, and assigned the ranks of the military commander of the five counties, the military officer of the five counties, and the military officer of the five counties, unless there were no other reasons. Those outside, generally do not carry.In November of the second year of Xianhe, Wu Xing, the prefect of Yutan, "supervised the military affairs of the five counties of Wu, Jinling, Xuancheng, and Yixing", which seemed to be the origin of the military post of the five counties in Kuaiji.There are nine people in the internal history of Kuaiji with the military rank of governor of the five prefectures, beginning with Wang Shu, as shown in the following table, and those who do not have the rank of governor in the internal history are not included. According to the above table and referring to other materials, we can see the following problems: For more than 40 years after Wang Shu, he did not see the military affairs of the five prefectures of Kuaiji, the governor of Kuaiji, which shows that there has been no major turmoil in Kuaiji for at least the past 40 years. This reflects the long-term stability of the eastern situation after Dujian took over Jingkou. Xi Yin, Wang Yun, and Wang Hui took up this post for other reasons, not because of the affairs of the five prefectures in Kuaiji.Xi Yin's position was due to Huan Wen's remuneration for the governor's land in Xuyan Erzhou, which he gave up at Zhenjingkou, reflecting the contradiction between Huan and Xi.Wang Yun's position was due to Xie An's arrangement for Wang Yun to cede the Xuzhou governor's territory in Zhenjingkou, reflecting the conflict between Xie and Wang.Wang Hui took up his post because Xie An did not allow Wang Hui to make a compromise on the Jiangzhou governor's strong momentum, which reflected the contradiction between Huan and Xie.Xi Yin, Wang Yun, and Wang Tai were modest and retired figures among the gentry. They held this position because they were expedient measures taken by the rulers when their sect was not very powerful, and did not reflect the needs of the Eastern situation.The east had this need when Xie Yan took office to suppress the peasant uprising in the east. After Wang Shu for more than 70 years, the five counties of Kuaiji were relatively stable during these 70 years. Except for Liu Laozhi and He Wuji at the end of the Eastern Jin Dynasty, those who held this post were all powerful and noble figures, including the Wang family of Langya (Shu, Hui), the Xi family of Gaoping (Yin), the Wang family of Taiyuan (Yun), and the Chen Jun family. The Xie family (Yan), the Kuaiji Kong family (Ji Gong) and the Eastern Jin royal family (Xiu Zhi).Except for Kong Jigong, all of them were from the noble family with the surname of overseas Chinese.According to the appearance of those who occupy their posts, they are comparable to those who live in Yangzhou, Jingzhou, and Xuzhou. At the end of the Eastern Jin Dynasty, when Sun En and Lu Xunyi's army were active in Kuaiji County, this post was first held by Xuzhou governor Xie Tan, and then by Liu Laozhi, the head of the Northern Palace.The composition of the head of the Beifu changed, from the noble family to the military general of the second-class noble family, as did the governor of Kuaiji.Therefore, He Wuji was granted the title of governor of Kuaiji.After the chief general of Beifu concurrently served as the governor of Kuaiji, the eastern counties were gradually not directly controlled by the imperial court but by the nearby Beifu, and the power of the governor of Kuaiji also became lighter.During the period between Lu Xun’s withdrawal from the boundaries of the five prefectures in Kuaiji and the founding of Liu Song, the military value of Kuaiji declined, especially when Liu Yu or his clan lived in Jingkou. "Song Shu" volume three "Emperor Wu Ji" (Part 2) In the first month of the second year of Yongchu (421), "dismissing the Kuaiji county government", Wu Tingxie thought it was the dismissal of the military post of the governor, Kuaiji, very much. There is also a reason why the last governor of Kuaiji was Nanshi Kong Jigong.According to "The Biography of He Wuji" in Volume 85 of "Book of Jin" and "Biography of Kong Jigong" in Volume 54 of "Book of Songs", when Liu Yu attacked Lu Xun, He Wuji once said Liu Yu in the third year of Yuanxing (403). He raised troops in Shanyin, Kuaiji, to attack Huanxuan of Jiankang.Liu Yu sought out Kong Jigong (named Jing, the grandson of Kong Yu), a local tyrant in Shanyin. Kong Jigong advised Liu Yu to act righteously when Huanxuan formally usurped the throne. "Jinlouzi" volume six "Miscellaneous Notes": "Kong Jing (that is, Jing) lives in the shade of the mountain. When Song Wuwei was quiet, he was in the east, so he went to wait for him. When he was quiet, he slept in the daytime, and the dreamer said: 'The Son of Heaven is at the door'. I feel Wu immediately sent people out to see, and the emperor also arrived. Jingxu has been connected, and he is still staying at the emperor's residence....Zeiping, the capital regards the emperor as the Fenwei general, and the internal history of Kuaiji" and so on.The case matter "Taiping Yulan" volume 128 quotes "Shu Yi Ji" which is similar, except that Kong Jingyan entered Liu Yu more, "make a bequest, leave the emperor's hand and say: "The empress must be a noble, and I wish to use it The heir is the entrustment. 'Emperor Xu Zhi' all words.It can be seen from this that Liu Yu and Kong Jigong established their relationship very early, and Kong contributed a lot to Liu Yu's pacification and Jiankang. "The Biography of Kong Jing" Volume 27 of "Southern History" says that Liu Yu originally wanted to start an incident in Shanyin, but Kong Jing stopped it with a long road.Liu Yu once led his troops into and out of Shanyin many times, and was greatly supported by Kong Jigong.Later, Liu Yu took Kong Jigong as the governor of Kuaiji to repay his old friendship.But by this time, the governor of Kuaiji had no practical effect. In the eyes of the people at the time, the five prefectures of Kuaiji really formed a region of their own, not only in terms of military affairs. "Shi Shuo Xin Yu · Enmity": Wang Xizhi and Wang Shu were at odds with each other. The imperial court, please divide Kuaiji into Yuezhou." Wang Xizhi did not want to be inferior to the above, but made this request, which shows that Kuaiji and other counties are likely to be divided.Although this discussion did not become a reality in the Eastern Jin Dynasty.However, in the first year of Song Xiaojian (454), the five prefectures of Kuaiji were cut off as Dongyang Prefecture, which actually realized Wang Xizhi's previous proposal. Between Kuaiji and Jiankang, convenient transportation must be maintained in order to meet the needs of Kuaiji's status.From Kuaiji to Jiankang, it usually goes westward through Qiantang, north to Wujun, northwest through Jinling (now Changzhou), Qu'a (now Danyang) to Jingkou, and then goes westward along the Yangtze River.Jingkou is the hub of this traffic line. Looking back at history, Sun Quan moved his government several times in Jiangdong, and it was along this line of communication that he moved.The Sun family originated from Fuchun, belonging to Wujun and adjacent to Kuaiji in the east.After the Sun family returned to Jiangdong from Huai, they originally took Wu as their governing place.At that time, Sun Quan was mainly using troops against Shanyue, and had no time to look outside. It was safer and more convenient to set up the rule in Wu.With the development of the situation, Sun Wu's power expanded to the middle reaches of the Yangtze River, and the remote Wu land between the lake and the sea no longer met the needs.In order to facilitate the battle with Huang Zu, Sun Quan moved his government office to Jingkou (called the capital at that time) in the thirteenth year of Jian'an (208).During the Battle of Chibi, Sun Quan was stationed here.In the sixteenth year of Jian'an, Sun Quan traveled westward from Jingkou, ruled in Moling, and changed Moling to Jianye. "Three Kingdoms · Wu Zhi · Zhang Hong Biography" notes and quotes "Xiandi Chunqiu" records Sun Quan said: "Moling has a small river for more than a hundred miles, which can accommodate large ships. We manage the water army, and we should move it." The small river refers to the Qinhuai water.In order to defend Jianye, Sun Quan built a stone city in the west of Jianye City where the Qinhuai River entered the river; he also built Ruxuwu in the south of Chaohu Lake to prevent invasion from upstream. Volume 28 of "Yimen Reading Secretary" said: "The city is built with stones to prepare for land, and the beard is used to prepare for water, and then Jiankang will be strong." Later, Wu State moved to Wuchang temporarily twice, but Jianye was always the political center of Wu State. , this situation remained unchanged throughout the Eastern Jin and Southern Dynasties. Sun Quan traveled along this route from Wuhui to Jianye via Jingkou. From then on, Jianye gradually prospered, and the traffic route from Wuhui to Jianye played an extremely important role. It is Jingkou. "Three Kingdoms · Wu Zhi · Sun Shao Biography" Sun Quan led the army from Danyang (Junzhi Jianye) to return to Wu through the capital, and "Sun Quan Biography" Sun Quan returned from Jianye to Qiting (in the northwest of Changzhou) to return to Wu, all via this route. The traffic line from Kuaiji to Qiantang, Wu and Jingkou to Jianye is mainly a waterway, and each section of the waterway was formed very early, but the situation is not the same.According to the five parts of the East Zhejiang Canal, the Qiantang Jinling Section of the Jiangnan Canal, the Jinling Jingkou Section of the Jiangnan Canal, the Jingkou Jiankang Waterway, and the Pogangdu, they are described as follows. From Shanyin in Kuaiji County to Qiantang in the west and Yuyao in the east to connect with the Yuyao River, there has long been a canal connected, which is the so-called East Zhejiang Canal in later generations.In the eastern part of Zhejiang, "Shui Jing Mian Shui Zhu" states that "Wan Liu gathers together, Taohu Lake is flooded, touches the ground to form a river, and branches and rivers intersect with canals." According to the sixth volume of "Wuyue Spring and Autumn", the king of Yue established his country, "by boat They are used as carts, and paddles are used as horses." In the same book, Volume 10, Fan Li went to Yue, "taking a flat boat out of the three rivers and entering the five lakes". . Volume 8 of "Yuejueshu" "The old waterway of Shanyin, out of Dongguo, from Junyang Chunting, to the county for fifty miles." This refers to the canal from Shanyin to Shangyu, which is probably the oldest section of the canal in eastern Zhejiang.This section of waterway entered the mirror lake after Ma Zhen opened it in the fifth year of Yonghe in the Eastern Han Dynasty (140), and boats sailed in the lake.In addition, Volume 10 of "Jiatai Huiji Zhi" quoted "Yuezhou Tujing", saying that Wei Hexun of the Western Jin Dynasty suggested building the Shanyin Canal, which probably refers to the section from Shanyin to the west to Qiantang. Difficult to ascertain. To the north of Qiantang, the canal that goes around Taihu Lake and reaches Jinling, which is the southern and middle sections of the Jiangnan Canal.In this area, the land is flat and the soil is thick, and the water network is staggered. It is relatively easy to excavate and connect it manually. It is estimated that this section of the canal appeared earlier, or in the late Spring and Autumn Period. This is the northern section of the Jiangnan Canal, and its excavation is much more complicated than the southern section of the middle section of the Jiangnan Canal.The Jinling Mausoleum turns north and gradually enters the hilly area at the highest point of the Jiangnan canal channel, and the water level has a large drop.When the canal passes here, new water sources must be added to ensure smooth flow, so the Lianhu Lake in Danyang appeared. "Taiping Yulan" volume six or six Gu Yewang's "Yu Di Zhi": "Liantang, established by Chen Min, curbs the Gaoling water, and uses the stream as the back lake." And "Yuanhe county map" volume two and five runs Danyang County, Zhouzhou: "Lian Lake is 120 steps north of the county, and it is 40 miles away from the week. In the Jin Dynasty, Chen Min was in chaos and occupied the east of the Yangtze River. He wanted to repair the farming achievements, and ordered his younger brother to restrain the Malin River to irrigate Yunyang (the case is Danyang), also known as Liantang, irrigates hundreds of hectares of land." Lianhu may have irrigation benefits, but the purpose of Chen Min's trip to the south was to transport rice grains from the south to Zhongzhou, so dredging the canal should be more urgent.The purpose of Kailian Lake is mainly to store water to benefit this section of the canal, and also to benefit from irrigation.In the first year of Jianwu (317), which was ten years later than Chen Min, Sima Zhong ordered the opening of Dingmaodai to connect the canal to Guangling, which proved that this section of the canal was usable during Chen Min's time.When the water in the canals of the Tang Dynasty was astringent, water from the lake was also used as an adjustment.Lianhu Lake in Song Dynasty can still play a regulating role. "History of the Song Dynasty" Volume Nine Six "Hequ Zhi": In the fourth year of Daguan (1110) "August, the ministers said: "There is a secretary to practice the lake to give Maoshan Taoism. The fields of Runzhou are high, and the canal is Jiagang, the water It is easy to dry up, relying on the lake to help. Please don't use the Tianhuang River to swell the sand fields to give it, but still order Changping officials to examine the predecessors' planning and construction.' Follow it." The same book and the same volume in the fifth year of Xuanhe (1123)" The ministers said: Lianhu Lake in Zhenjiang Prefecture is geographically connected with Xinfengtang, with more than 800 hectares, irrigating the fields of the four counties. There is one inch of lake water and one foot of water, and it has been around for a long time. Now the embankment is damaged and cannot store water. Beg to wait The gaps between the farms are repaired in turn." The sayings here, "The canal is placed between the hills, the water is shallow and easy to dry up, and the lake is used for food", and the words "one inch of lake water, one foot of potential, and it has been around for a long time" are more evidence of practice. The excavation of the pond is important to maintain the navigation of the entire Jiangnan Canal; and the collapse of Lianhu caused the drying up of this section of the canal, making the canal unable to be fully navigable.This has always been the case and did not begin in the Northern Song Dynasty.It seems that since this section of the canal was dug, due to the difficulty of maintaining navigation conditions, it has been in a state of congestion from time to time. Volume 1 of "Entering Shu Ji" records that Lu You travels this section from south to north, saying that Zilian Lake crossing Jiagang is Xinfeng Lake, "Jiagang is like a series of mountains, covering the soil accumulated at that time." At the highest point of the canal in the Jinling section of Jingkou, Lailian Lake and Xinfeng Lake adjust and replenish water. "At that time" in "Entering Shu Ji" refers to the time of Emperor Sui Yang, but I don't think it may not be earlier. It is also difficult to determine when this section of the canal was first dug. Volume 2 of "Yue Jue Shu": "Wu Gu's old waterway... entered the great river and played Guangling".Take Fuchai's deeds of crossing the great river to open up Hangou, which proves that it is not impossible for him to preside over the opening of the Jinling-Jingkou Canal.However, to maintain the stable navigation of this section of the canal is not a problem that can be solved in the era of King Wu.Danyang, the land of ancient Yunyang, is said to have been said by Qin Shihuang, who looked after Qi, that the land had a kingly spirit, so he dug a hill and cut its straight path to make it Aqu, so as to defeat its power, so it is called Qu'a.The reason for this cannot be verified.But geographers believe that there is a kind of historical truth in it, that is, the straight road envoy Aqu met the requirements for improving the waterway between Jinling and Jingkou.Because the canal runs from Jinling and Danyang to the north, the water level drop is relatively large, and the meandering flow to extend the river course and slow down the slope is a scientific method instead of building dikes and weirs.It can be seen from this that when Qin Shihuang cut off Yunyang Road and made it Aqu, it was an important improvement in the navigation conditions of this section of the canal. During the Sun Wu period, the Danyang Canal seemed to be passable. "Book of Southern Qi" Volume 14 "Zhou County Chronicles" (Part 1): "South Xuzhou, Zhenjingkou.... Dantu Waterway enters Tongwuhui, and Sun Quanchu towned it." According to "Taiping Yulan" Volume 170 Quoting "Wu Zhi" said: "Cen Hun chiseled Dantu to Yunyang, while Du Ye and Xiao Xinjian cut off Jue's mausoleum, and their skills were arduous (original note: Du Ye belongs to Dantu, Xiao Xin belongs to Qu'a)." The case of Cen Hun was Wu Weiren. "Wu Zhi·Sun Hao Biography" recorded in Tianji three years (279) that Cen Hun "was fond of utilitarianism, and everyone suffered from suffering".This seems to refer to his meritorious service such as digging this section of the canal.Based on this, it can be seen that Cen Hun's achievement of "killing the mausoleum attack" is another major transformation of this section of the canal.Today's Changzhou Zhenjiang section of the Great Jiangnan Canal has undulating hills and ridges on both banks, and the river course is tortuous, which is quite different from the middle and southern sections. Generally speaking, there is still no evidence whether the Jinling Jingkou Canal was first dug at the time of Wu Wang Fuchai.Afterwards, first, the Qin Dynasty changed the straight road to make twists and turns; second, at the end of the Sun and Wu Dynasties, "cut off the mausoleum attack" and divert the water to guide its flow; third, in the early Eastern Jin Dynasty, the lake was opened and Dingmaodai was established to adjust the water volume, so that , this section of the canal has become a fairly large-scale waterway, which has been able to exert its benefits in the Eastern Jin and Southern Dynasties. The last section of the traffic line from Kuaiji to Jiankang is the Dajiang between Jingkou and Jiankang.In the Eastern Jin and Southern Dynasties, the place where the great river entered the sea was at Jingkou.Jingkou Dajiang, according to the lost article in the "Yuanhe County Tuzhi", is more than forty miles wide.Guangling on the other side of Jingkou is a place to watch the waves, and the waves are terrifying.Emperor Wen of Wei's army came to Guangling and could not cross, sighing that the sky is limited to the north and the south.In the Eastern Jin Dynasty, Guangling crossed the river like flooding the sea.After the boat travels from Kuaiji to Jingkou, it leaves the canal and enters the Dajiang River. It flows back for more than a hundred miles before reaching Jiankang.There are many risks in the big river, and it is difficult to guarantee drowning when a canal boat enters the river; and it is too long to go around the Jingkou. In order to shorten the waterway journey from Kuaiji to Jiankang, and to avoid the danger of the great river, it was necessary to build another waterway. "Three Kingdoms · Wu Zhi · Sun Quan Biography" Chiwu eight years (245 years), "The school lieutenant Chen Xun will garrison fields and 30,000 scholars, digging the middle way of Jurong, from childhood to Yunyang West City, Tonghui City, Make evil pavilion", called Pogangdu. The second volume of "Jiankang Records" says that Pogangdu got the "ships of Tongwuhui". Volume 73 of "Taiping Yulan" quoted Zhang Bo's "Wu Lu": "In Jurong County, the great emperor (Sun Quan) ordered Chen Xun to dig the waterway and set up twelve dais (the case should be 14 dais, see below), It is said that all the prefectures will be connected to Wu, so the ship will no longer go from Jingkou." Pogangdu was completed and exerted great benefits, no doubt it was in the period of Sun Wu, but the initial construction may have been much earlier. "Tongjian" Jiazi Tiaohu's note in June of the first year of Datong in Liangzhong said: "Poling,... Qin Shihuang dug it, that is, Pogang." However, it is still unknown whether it can be transported by ship at that time. Pogangdu is mainly located in today's Jurong County.To the south of reading is the northern foot of Maoshan mountain range; to the north of Du, between Jingkou and Jiankang, there is a mountain range called Ningzhen standing by the river.Pogangdu is located in the hills between the two northern and southern mountain ranges.In the west and east of the hills, there are small rivers flowing westward into the Qinhuai River and eastward into the Danyang Canal.Between the sources of two small rivers that flow in the opposite direction is Pogang, also known as Poling, Podun (Volume 20 of Minutes of Reading History and Fangyu), and Pogang (Volume 11 of "Zhengao").Pogangdu means digging hills for reading, connecting small waters at both ends, so that Wuhui ships can enter the Yangtze River from Danyang and Jingkou to Jiankang, but can go westward from Danyang, cross Pogangdu, enter Qinhuai River and go northward. Volume 2 and 5 of "Reading History Fangyu Minutes" quoted "Yu Dizhi", saying that Pogangdu "seven dais are on the upper and lower sides. Prince Liang tabooed it, abolished Pogangdu, and don't open Shangrongdu... Chen Fuburied Shangrong, repaired the broken hills and dug. Until the Sui Dynasty, Chen was flattened, and it was abolished. The capital of the Six Dynasties was Jiankang, and Wu Hui transferred it, all from Yunyang to the capital." Pogangdu is located in a mountainous and hilly area. There are 14 dais within a short distance, and they go up and down seven times. Passing the dais is usually pulled by manpower and ox power, so it is very difficult to travel by boat, and it is difficult to ensure frequent water navigation.In the historical records of the Eastern Jin and Southern Dynasties, there are often records about Pogangdu. "Shi Shuo Xin Yu Gui Zhen": "He Sikong (fun) went out to Pogang..." "Zhengao" Volume 19 Note: "I and Wang Lingqi set out on the same boat and arrived at Pogangdai." In the Book of Songs, Volume 4, "Shaodi Ji" and Volume 43, "Xu Xian's Biography", it is said that the Shaodi opened up and gathered soil in Hualin Garden, and took pleasure in leading boats from left to right like breaking hills and singing. "Book of Songs" volume ninety-nine "Yuan Ji Shao Zhuan", Shao sent people to "destroy the cypress (the word for this case) Gangfangshandai, so as to eliminate the Eastern Army". "Liang Shu" Volume 33 "Xiao Hui Biography": "There was a lot of chaos in the Three Wus, and the ancestors ordered him to come out and break the hill." The second generation of Qi and Liang, the mausoleums are all in Danyang, the Zigong is transferred, and the mausoleum is visited. Follow Pogangdu. Generally speaking, the opening of Pogang Reading has greatly facilitated the personnel exchanges and information transmission between Wuhui and Jiankang, enabling the powerful and powerful figures who lived in the late east to maintain more convenient contact with the imperial court, and even the deployment of troops can also be followed. Follow this path.However, due to the limitation of river conditions and the obstruction of government privileges, it may be difficult for traveling merchants to have this convenience. "Book of Southern Qi" Volume 21 "Biography of Prince Jingling Liang" said that the Taiwan envoy was in a hurry to seek the emblem, and he was lucky on his own. Pass your own boat." The water is small and urgent, and ships cannot go parallel, so the benefits of passing the Dai first will naturally belong to the government.Therefore, it is unlikely to rely on the Pogangdu to solve the problem of bulk material transfer.The water transportation of Wuhui's grain and grain must also pass through Jingkou.Therefore, once the vicinity of Jingkou was disturbed in the Eastern Jin Dynasty, the Jingshi Lianggu panicked.This can also explain that as a traffic route, Pogangdu has more political significance than economic significance and can only play an auxiliary role.The real transfer hub between Jiankang and Kuaiji is still Jingkou.The previous quotations from the "Wu Lu" that "the boats will no longer pass from Jingkou" and "The Minutes of Reading History and Fangyu" that "Wu Hui transfers all from Yunyang to the capital" are all exaggerations and do not fully correspond to the reality. Condition. Although Jingkou has a pivotal position between Jiankang and the Three Wus, during the Wei and Jin Dynasties, the area around Jingkou and Jinling was still very barren, wild and wild, and wild animals haunted it.At the beginning of the Three Kingdoms, Sun Quan often came here for hunting. "Wu Zhi Sun Quan Biography" in the second and third year of Jian'an (218) "Quan will be like Wu, he personally rides a horse to hunt a tiger in Qiting, and the horse is injured by the tiger." place.To the southeast of Jingkou and to the northwest of Taihu Lake, in the time of Sun Wu, it was the farming area of ​​Piling Diannong Xiaowei. It can be seen that there are very few households in this area, and the land is uncultivated.In the Western Jin Dynasty, the farmland was turned into a prefecture and county, starting with the establishment of Piling County, and in the Eastern Jin Dynasty it was changed to Jinling County. The land of Jinling is thin, far inferior to that of Wu. Volume 25 of "Yuanhe County Tuzhi" says: "The old Jinlings are vast and sparsely populated, and there are few canals, and the fields are dirty and evil." Volume 293 of "Taiping Guangji" quotes "Sou Shen Ji", saying The capital is "a lot of grass and dirty".Officials pay attention to building water conservancy in order to increase the number of households who cultivate fields.The aforementioned Chen Min Kailian Lake and Zhang Kai Kai Xinfeng Lake are all here.According to the note in "Shishuoxinyu · Guizhen": Xinfengtang was named Fumintang at that time, and Ge Hong in Danyang wrote "Ode to Fumintang". Volume 74 of "Beitang Shuchao" quotes "Jinzhong Xingshu" as saying that Xinfengtang is "ninety-four feet square".The function of Lianhu Lake is mainly to adjust the water volume of the canal, so the irrigation benefits may not be great.In the second year of Xiankang, Emperor Cheng of the Jin Dynasty (336), there was a ban on sealing up mountains and swamps, and more than ten feet of stolen goods were abandoned in the market.Mountains and lakes can be sealed off. When it comes to barren mountains and wild lakes that have not been developed, Jingkou is severely sealed off. It can be seen that production is very backward.The Diao family, who lived in Jingkou, declined after the death of Diao Xie. Xiankang was still a poor family. Due to the business of farming, by the end of the Eastern Jin Dynasty, it was a rich man with thousands of acres of land and thousands of slaves.The fields stretching to ten thousand hectares should belong to the genus of Pitian and Caotian, which is what Diao said in his biography of "solid and stingy mountains and swamps", which shows that the land is barren, not that the agriculture is developed.In the Southern Dynasties, Ren Fang's "Shu Yi Ji" still said that there were many tigers in Piling. Volume 170 of "Taiping Yulan" quoted "Yu Di Zhi" as saying, "The soil in the Dantu world is as firm as wax. The proverb says: 'Be born in Soochow, die in Dantu. , Dantu can be buried." Until the Southern Song Dynasty Wang Yuanliang's poem "Jingkou Yewang", there was still a sentence "Nanxu white day tigers form an array", see Volume 2 of "Additional Hushan Classigraphy". It is this barren and barren place that has attracted a large number of exiles since the end of the Western Jin Dynasty, including nobles and civilians.Fan Yang Zuti led his troops to the south and once stayed in Jingkou.Bohai Diaoxie, descendants of descendants who came from the south lived in Jingkou for generations.Yingchuan Yuliang's family is in Jiyang, which belongs to Jinling.Xu Chengzhi of Dongguan and Zang Kun, a villager, led their children and more than a thousand families of scholars and commoners to cross south. They lived in Jingkou for generations. The graves of the two families are in Jinling and Dantu respectively.Liu Yu of Pengcheng moved to Jingkou since Gaozu.There are many generals from the Beifu who left the capital.Xiao Daocheng and Xiao Yan of Lanling lived in Wujin. Scattered refugees also came to Jingkou. "Song Shu" volume three and five "Zhou County Chronicles" South Xuzhou article: "Jin Yongjia chaos, You, Ji, Qing, Bing, Yan and other states and Huaibei exiles in Xuzhou led the Huai River, and also crossed the river in Jinling County Boundary. In the fourth year of Jincheng Emperor Xianhe (329), Sikong Xijian was also a refugee in Huainan in the counties of Jinling." According to "Book of Jin" Volume 67 "Xijian Biography", Xijian was to Jingkou and Jinling流民“处与田宅，渐得少安。”谭其骧先生《晋永嘉丧乱后之民族迁徙》一文，估计南徐州（案即东晋的徐州）的侨旧人口总数为四十二万人，其中侨寓之民约为二十二万。按照东晋制度，僮奴不入籍，客虽得“注家籍”，但漏注者多。流民在徐州为僮为客而未着籍者，当然未计入此二十二万之内。从人口数字看，徐州是江左侨寓人口最为集中的地方。 京口、晋陵的自然条件，如前说既然非常不好，为什么却成为流民最集中的地方呢？青、兖、徐州流民乘泗逾淮，循中渎水或泛海南来，自然顺道；但是幽、冀、并州流民为什么也要绕道而来，定居于江南东隅的海渚呢？这个问题，除了晋陵地广人稀，郗鉴可以对流民“处与田宅”之外，还有出于安全的原因。 士族南来，只要不与吴姓士族利益冲突，也就是说只要他们愿意逐空荒而居，其停驻地就有较大的选择自由。例如闽中之地，他们也能率先进入。《太平御览》卷一七零引梁载言《十道志》：“东晋南渡，衣冠士族多萃其地，以求安堵，因立晋安郡。”《元和姓纂》卷五：“晋安，林放之后，晋永嘉渡江，居泉州。”《直斋书录解题》卷八引林諝《闽中记》曰：“永嘉之乱，中原仕族林、黄、陈、郑四姓先入闽。”但是零散的流民，却没有多少自由选择停驻之处的余地。他们在胡骑追逼下节节南行，一般只是想找一个接近北土的地方停留，以便有朝一日重返故园。他们资财匮乏，人力寡弱，一旦到达可以暂时栖息的安全地方以后，就无力继续南行。所以他们集中寄寓的地方，一般限于长江南缘一带，至少在东晋初午是这样。以下游而论，下游南缘胡骑难于到达的地方，比较理想的是江南的东隅，也就是京口、晋陵一带。下游受敌之地，可能是寿春、合肥，也可能是历阳、建康，但不大可能是远至东隅的广陵、京口。特别是京口，宽四十里的长江，是它的一道重要屏障。陆游《入蜀记》卷二有采石江面狭于瓜洲之言，《读史方舆纪要》卷二五据此，曰：“古来江南有事，从采石渡江者十之九，从京口渡江者十之一，盖以（采石）江面狭于（京口）瓜洲也。”卷三一“江乘”条亦曰：“自古南北之津，上则由采石，下则由江乘，而京口不当往来之道。”《十七史商榷》卷五八“京口名义”条，谓“从北朝来，当于瓜步渡江，在今六合县，不由丹徒。”据陆游、顾炎武、顾祖禹、王鸣盛等人所论，京口在晋代不当南北之津，自然比较安全，这应当是吸引北方流民的一个重要条件。事实上，终东晋之世，京口曾是几次北伐出兵之地，而北方胡骑进攻广陵、京口之例，却一次也没有。 京口、晋陵可以吸引流民，而流民可以组成军队。京口、晋陵密迩三吴，而三吴的物产可以支援京口之军。郗鉴利用这支流民军队和三吴粮谷，经营京口，使京口成为东晋时具有特殊作用的重镇，影响着东晋的朝局。 郗鉴以流民帅身分率众南来，他以后的活动都与流民有关系，力量的基础始终是流民。一直到他临终上疏，还是谆谆以流民事为重。 关于京口的作用，历来史家独重谢安以谢玄据京口创建北府兵之事，这无疑是有理由的。但是北府其所以具有这种地位，其所以能够发挥这种作用，首先是由于前此郗鉴的长期经营。否则，谢玄也不可能在短期之内，在京口建成一支足以支配南北关系和东晋政局的北府兵。 京口在郗鉴经营时期，已经发挥颇为显著的作用，概括言之，有控制三吴、抵御海盗、拱卫京师三个方面。 在琅邪王司马睿南渡江以迄东晋初年的大约二十年内，朝廷和执政并未认识到京口的重要性，没有人去特意经营。京口成为重镇，是从苏峻之乱时由于控制三吴地区的需要开始的。首倡“静镇京口”的郗鉴受命为都督八郡诸军事，并节度浙东的王舒之军和浙西的虞潭之军，显示出京口具有控制三吴的功能。这种功能一直维持下去，东晋末年，居京口的北府主将取得了更大的权势，京口对于三吴的控制也就更为明显。三吴大规模的农民起义，就是由来自京口的军队压平的。这种种情况，已在或将在它处论及，这里从略。 海寇骚扰，是晋成帝时的一个颇为严重的问题。海寇著者，一为刘征，一为韩雍，都是由北方的青、徐泛海南扰的石勒部将。《晋书》卷七《成帝纪》咸和五年（330年）五月，“石勒将刘征寇南沙（今常熟西北，有司盐都尉），都尉许儒遇害，进入海虞（今常熟）。”咸和六年正月“癸已，刘征复寇娄县（今昆山），遂掠武进（今常州）。乙未，进司空郗鉴都督吴国诸军事。戊午，以运漕不继，发王公以下千余丁，各运米六斛。”这几次海寇骚扰所至，都在晋陵、吴郡各地，逼近京口，迫使“静镇京口”的郗鉴加强京口防务。《郗鉴传》：“时贼帅刘征聚众数千，浮海抄东南诸县。鉴遂城京口，加都督扬州之晋陵、吴郡诸军事，率众讨平之”。《晋书》卷六七《虞潭传》，潭为吴郡太守，“修沪渎垒（在今上海市西北）以防海抄，百姓赖之。”事在郗鉴城京口约略同时。 韩雍抄寇事，在咸和七年（332年）三月。《成帝纪》：是月晋将赵胤、匡术“攻石勒马头坞（今安徽怀远南），克之。勒将韩雍寇南沙及海虞。”《石勒载记》：“晋将军赵胤攻克马头，石堪遣将军韩雍救之，至则无及，遂寇南沙、海虞，俘获五千余人。”韩雍救马头不及而转南寇抄，当为循淮入海而下；“俘获五千人”，当指韩雍所俘南人而非东晋所俘北人。这说明晋陵一带虽然得免于北寇陆上侵袭，比较安全，但在海寇抄略之时则又首当其冲。所以郗鉴城京口以御海寇，是那时加强防务所必需的军事措施，否则海寇溯江而上，陷京口，攻江乘，扰建康，对东晋的威胁就更大了。此后海寇很少，应当说京口防御加强是重要原因。 苏峻之乱的形势，使京口成为建康“东门”。其时郗鉴自广陵过江，本在京口，可西向策应建康，也可南向策应三吴。后来郗鉴奉召西行，与陶侃会，三吴的王舒、虞潭遂失策应，作战不利。《晋书》卷七八《孔坦传》，坦为陶侃长史，其时“郗鉴镇京口，侃等各以兵会，〔鉴〕既至，坦议以为'本不应须召郗公，遂使东门无限。今宜遣还，虽晚，犹胜不也。'侃等犹疑，坦固争甚切，始令鉴还据京口。”郗鉴遂与后将军郭默还丹徒，立大业、曲阿、庱亭三垒以拒苏峻所遣军队，直到苏峻之乱弭平。以此为契机，郗鉴及其后人长期留在京口，在京口起着支配作用。 京口重镇，据《晋书》卷七七《蔡谟传》说，其所统“东至土山（案即北固山），西至江乘，镇守八所，城垒凡十一处，烽火楼望三十余处。”蔡谟为郗鉴后任，他镇京口时军事设施如此，当沿袭郗鉴规模。 《南齐书》卷一四《州郡志》南徐州条曰：“今京城（案即京口）因山为垒，望海临江，缘江为境，似河内郡，内镇优重。宋氏以来，桑梓帝宅，江左流寓，多出膏腴。”《读史方舆纪要》卷二五也把京口之于建康，比之于孟津之于洛阳，孟津为洛阳门户锁钥，京口亦为建康门户锁钥。司马氏出自河内而于洛阳成其帝业，刘、萧则起自京口、晋陵而称帝于建康。因帝乡而多膏腴，京口也同河内一样。 京口拱卫建康，主要是具有战略意义。从战术上说来，建康自有石头、白石等门户，特别是石头城。孙吴迁都建业之日，就立石头以屯军。周札开石头之门，王敦遂得以制建康；苏峻取得台城，必倚石头方能固守。这都是战术形势使然。至于京口，形成重镇以后，其战略价值表现在：一，起威慑作用，减少甚或阻止建康变局的出现。陶侃、庾亮惮郗鉴而不敢贸然兴师废黜王导，就是证明。二，尽管朝局已变，京口还有可能扭转局面，刘裕自京口驱逐桓玄，就是证明。由于东晋建康处在长江上游的军事压力之下，荆豫诸州动辄拥兵犯禁，京口作为建康东门重镇，更得以显示其重要性。 我们可以把京口在孙吴时期和东晋时期发挥的作用，略作比较。孙吴设京下督，宗室孙韶、孙越以及顾承等均曾为之。京下督所司，除连接建康与三吴以外，据《吴志·孙韶传》，主要是观察江北动静，防备魏军。所以京下督虽然密迩京师，从其职能看来只能算是吴之外镇，对吴国京畿政局并不起直接影响。 其时上游荆州一直在孙吴的稳定控制之中，不存在顺流问鼎之虞。东晋则不然。东晋荆扬相持的政治格局业已形成，京口重镇的职能主要不是对外而是对内，起着防备上游以稳定建康的作用，因而获得“内镇优重”的特殊地位。日后东晋政局的变迁历程，反覆证明着这一点。即令是在谢玄创建北府兵和淝水之战前后时期，京口也只是兼有外镇作用，其主要职能还不是外镇。 如果进一步考察京口在吴、东晋时期作用不同的原因，我们将发现，京口的“内镇优重”地位，正是东晋门阀政治的产物。荆、豫与扬、徐的关系，所反映的是各个士族门户之间的关系，这是门阀政治的地域表现，或者说是以门阀为背景的地缘政治。孙吴时期，门阀士族已在形成；江左的顾、陆、朱、张，已经具有特殊的社会政治地位。而且其时荆州上游又由陆氏人物世代据守达数十年之久，这一点，东晋时期盘据上游的士族还无法与之比拟。但是孙吴时的建业并不依赖京口以与上游抗衡。所以我们在用东晋门阀政治解释京口作用的时候，还要看到东晋主弱臣强的状况，看到东晋司马家与士族“共天下”的现象，而这些在孙吴的历史上却看不到。孙吴时上游与下游重镇，同处在皇权控制之下，而东晋则不然。孙吴时的士族是皇权下的士族，东晋的士族则是与皇权并立的士族。这同样是我们考察京口在吴、东晋时期作用不同的原因时必须注意的一个问题。 郗鉴死于成帝咸康五年（339年）八月，其年七月王导死，翌年正月庾亮死。三巨头之死全在这半年之内，他们之间的复杂关系所构成的政治暗流，至此应当不复存在。但是作为家族，王、庾、郗都还在继续发展。三个家族的后人中虽然未再出现象王导、庾亮、郗鉴那样足以左右政局的人物，但是原来政局的影响，还若隐若现地存在着并且继续起著作用。 郗鉴死前上疏逊位曰：“臣所统错杂，率多北人，或逼迁徙，或是新附。百姓怀土，皆有归本之心。臣宣国恩，示以好恶，处与田宅，渐得少安。闻臣疾笃，众情骇动。若当北渡，必启寇心。”案，此年上游庾亮作态，声称欲开复中原，而郗鉴议以资用未备，不可大举。郗鉴逊位疏中所陈，就是指此。庾亮声言北伐之时，必有请郗鉴移镇北上以为形援之事，故郗鉴疏中谆谆以京口之众不可北渡为言。郗鉴还以其所刺徐、兖二州，分别荐太常蔡谟及兄子晋陵内史郗迈以自代，一处京口，一处广陵。其荐郗迈曰：迈“谦爱养士，甚为流亡所宗，又是臣门户子弟”云云。《世说新语·德行》注引《晋中兴书》，述及郗迈仕履，不言莅兖州刺史之任，疑迈虽得鉴荐而朝廷未授。郗鉴荐迈而以门户为言，在当时门阀政治下是习见之事。《晋书》卷七四《桓冲传》：“初，郗鉴、庾亮、庾翼临终皆有表，树置亲戚”云云，郗鉴遗表树置者就是郗迈。为“流亡所宗”的郗迈，以江南的晋陵内史被荐为江北的兖州刺史，事虽未成，亦见江南江北流民隔江呼应之势。郗鉴不请以子郗愔自代徐州，特别是不以郗愔兼刺徐、兖二州，可能是基于愔传所说，愔“冲退”、“简默”，“无处世意”，难以居繁剧之故。其时郗愔年少无资望，可以为佐史，不可以为长吏。直到穆帝永和年间，郗愔犹“以资望少，不宜超莅大郡”为言，辞吴郡太守之授。 郗鉴荐蔡谟为徐州镇京口，主要因其笃慎之故。郗鉴疏中流露，鉴死前最大的忧虑，是庾亮以北伐为名逼京口之众北渡以削异己。所谓“若当北渡，必启寇心”云云，就是郗鉴婉转拒绝庾亮要求，以图保全自己实力之词。对于这个问题的态度，蔡谟咸康五年（339年）春间之议与郗鉴全同。甚至当永和五年（345年）石虎死后中原大乱，朝廷咸以为当太平复旧之时，蔡谟犹独谓“胡灭诚大庆也，然将贻王室之忧。”他的意思是说，竞言北伐者并无资实，行将疲民以逞，甚或借以行非常之事。他主张以保全晋室、暂安江左为重，寇不来我亦不往，以待局势的变化。东晋一朝持这种见解的臣僚前后甚多，王羲之、孙绰辈是其著者，他们持重苟安之心是一目了然的。然而处北伐之任者确实往往心存不测，而往往又是力不从心，难得逞其志向，徒滋江左纷扰。士族专兵，皇权不振，政治格局如此，无人可以挽回。直到刘裕当权后门阀士族统统丧失了兵权，情况才得以改变。 郗氏部曲义故在京口、晋陵者，郗鉴以田宅处之，他们与郗氏关系密切，自不待言。郗鉴死后朝廷想绥抚他们，必然要借重郗鉴子侄。所以郗鉴子侄居官者如果不在京口，就在与京口关系密切的会稽五郡。郗氏住宅、茔冢在京口，其家业亦有在会稽的始宁、章安等地者。郗氏家族在这一带的潜在势力，历久不衰。 兹将郗鉴以来至桓温得势时徐州都督刺史及其在职年分表列如下。都督徐州者多兼督兖州，而且例带扬州之晋陵诸军事。徐州例镇京口。其因北伐原因而移镇江北者，例如荀羡曾迁治淮阴，又迁下邳；郗昙、范汪、庾希、郗愔均曾治下邳，但他们势力重心仍然在京口。桓温为琅邪内史本治金城，迁徐州刺史后移镇京口。《晋书》卷八三《袁乔传》有“桓温镇京口”语，即此时事。但是桓温不久以后即迁荆州之任，在京口时间很短，并无影响。郗鉴初镇京口在成帝咸和元年（326年），郗愔被排挤出京口在废帝太和四年（369年）。郗氏家族势力支配京口、晋陵地区，前后历时四十三年之久。