Strategically, everyone knows that Zhao Kuangyin's decision to establish Kaifeng was a wrong decision at that time, and he realized this. He intended to move the capital to Luoyang, and even chose Gongyi, which was closer to Luoyang. However, due to his sudden death and the opposition of the ministers led by Zhao Kuangyi, it was never possible to complete, which laid the foreshadowing for the demise of the Northern Song Dynasty.

The Great Wall was not built in one day, and the embarrassing location of Kaifeng was not built in one day. In order to avoid the invasion of the Western Qin Kingdom and to advance eastward in the Warring States Period, King Hui of Wei moved the capital of Wei from Anyi to Yiyi, which was called "Daliang". The history of Kaifeng's city began from then on. The Wei Kingdom, after the three families divided the Jin Dynasty, seemed powerful, but in fact there were many crises. If Han and Wei were in a bad relationship, Hexi would be lost to Qin. In addition, it was defeated by Qi in the east, and Wei Kingdom turned from prosperity to decline.

However, Kaifeng was low and flat at that time, and it was easy to accumulate water and waterlogged. After King Hui of Wei established the capital of Daliang, he successively carried out a series of water control and diversion projects in Kaifeng cities. It drew the Yellow River water from Xingyang into the Putianze, then opened a large ditch, drew the Putian water flowing eastward, passed through Daliang City north and then turned south into Yingshui and Wohe River, forming a Honggou canal connecting the two major water systems of the Yellow River and the Huaihe River.

This gap played an incomparable role in the fate of Kaifeng's city. As a result, Daliang became the center of a well-connected water transport network, and the navigation capacity of each river channel was greatly improved. Daliang became a hub for water transportation in the Central Plains because it was located in the center of the Great Valley water system. It formed the so-called "north away from Yanzhao in the north, Jianghuai in the south, with a rich waterway city". This led to the southern parts. Once the south rebelled, the Liang Kingdom could resist first.

In addition, after the completion of the Honggou, it also improved the flood discharge capacity in Kaifeng area, eliminated nearby water accumulation, improved the irrigation conditions of farmland, and promoted the agricultural production and economic development of Wei State. In just a few decades, Daliang's neighborhood had become the main agricultural area of ​​Wei State, and the Wei State's regime was thus stabilized. It also posed a threat to the city. Later, the Qin general Wang Ben failed to attack Daliang for a long time, so he drew the water from Honggou to irrigate the city. After a century of prosperity, Daliang's city was tragically destroyed, and Wei State was destroyed.

After the establishment of the Sui Dynasty, in order to strengthen the transportation capacity of north and south, the Sui Dynasty dug the Tongji Canal, starting from Luoyang, diverting the valley water. The Luo River reached the Yellow River. After passing through a section of the Yellow River, it drove the Yellow River southeast at Banzhu, passed the city of Kaifeng, and entered the Huai River north of Xuyi County, Jiangsu, and communicated with the political center of Chang'an Luoyang, Chang'an, and the fish and rice town of Huaiyang, which was at that time, and gradually became a rich blood vessel center. Bianzhou is at the throat of the canal and has a prominent position in the transportation of grains, ushering in a new vitality.

In addition to being a hub for water transportation, Kaifeng in the Tang Dynasty was also a hub for land transportation. After traveling from Xi'an to Luoyang, and then heading east, northeast and southeast, there were three main roads, two of which had to pass through Bianzhou. Especially when the wealthy areas of the Tang Dynasty were important at that time, it had to pass through this. Since then, Bianzhou has actually gradually become a major domestic water and land transportation center and a general barrier for the national economic lifeline.

After the Anshi Rebellion, in order to avoid the capital being trapped due to interruption of the grain transportation, the Tang Dynasty specially set up the Xuanwu Army here and rebuilt the city of Bianzhou. Bianzhou became a military center in the Central Plains. In the late Tang Dynasty, the economic development level of the Yellow River Basin and the Yangtze River Basin became increasingly disparate, the north relied on the financial resources of the south, and the status of Bianzhou became increasingly important. At that time, people said: "Daliang was the key to the world, the bustling of boats and vehicles, the throat of the river and the river, and the transportation of the Huaihuo Lake."

Zhu Wen, the governor of the Xuanwu Army stationed in Bianzhou at the end of the Tang Dynasty, usurped the Tang Dynasty and established the Later Liang Dynasty, capitalized by Bianjing, and was called the Dongdu. Kaifeng became the capital of the country again. Among the regimes that changed after the Later Liang Dynasty, in addition to the Later Tang moving the capital to Luoyang, the Later Jin, Later Han and Later Zhou both regarded Bianzhou as their capital and was called Tokyo. Since the Later Jin Dynasty, Kaifeng established the status of the capital. Among these dynasties, the Later Zhou Emperor Zhou Shizong had a more profound impact on the transformation of Kaifeng City.

Zhou Shizong not only re-planned and built Kaifeng City, built Kaifeng new city, expanded outer city, and widened urban streets, but also focused on building water conservancy, dredging the Bian River, and restoring the previous water and land transportation network centered on Kaifeng. The construction of the Later Zhou Dynasty laid the foundation for the urban layout of Tokyo in the Northern Song Dynasty, and opened up the road for Kaifeng to become an administrative center city, and Kaifeng's capital status was easily consolidated.

After entering the Song Dynasty, although Chang'an and Luoyang were destroyed by years of war, Kaifeng had the opportunity to rise rapidly during the Five Dynasties period and become the political, economic and cultural center of the Central Plains, Zhao Kuangyin was not without hesitation when he really wanted to take action. It is true that Kaifeng has developed water and land transportation, which is conducive to controlling the vast Guandong region. After the construction of the Five Dynasties period and the four dynasties, the city and palace were relatively complete, but there were hidden dangers here.

Geographically, Kaifeng has almost no danger to defend around it, and is a typical "four battles place". As a country's capital, it is very unfavorable. In order to make up for the geographically unfavorable defense weakness of Kaifeng, the Song Dynasty had to station heavily in the capital to make up for it. After abandoning the capital Chang'an or Luoyang, the Northern Song Dynasty began to focus on developing Kaifeng, an important water city. At that time, the Huimin River, Bian River, Wuzhang River and Jinshui River passed through the city of Tokyo, which was known as the "Four Rivers Running the Capital". Tokyo became the center of the Bian River, Yellow River, Huimin River and Wuzhang River transporting the four rivers.

The branch of the Yellow River, the Bian River, brought prosperity to Kaifeng, but the hidden dangers of the Yellow River cannot be ignored. Due to long-term agricultural reclamation, soil erosion in the upper reaches of the Yellow River has become increasingly serious. Since the Northern Song Dynasty, the amount of sediment carried by the Yellow River has obviously accumulated in the river channels and has continuously changed lanes to the south to approach Kaifeng. The dense waterways nearby have also become the best channel for the Yellow River to discharge floods.

The repeated flooding of the Yellow River caused the "four major canal transports" mainly composed of the Yellow River and Bian River in the Northern Song Dynasty to be silted due to the damage to the Yellow River, and also changed the ecological environment in the region, making the surrounding area of ​​Kaifeng, which was once called the "northern water city", a vast sea of ​​sand. The frequent wars in the later period caused the Yellow River to divert its route many times and broke its way in Kaifeng area many times. Then the Mongols and Yuan further moved the Grand Canal eastward and changed to southwest Shandong without using Henan. At this point, Kaifeng's decline was out of control.

As a modern person, Zhao Bing knew more about the period from the Song Dynasty to the late Qing Dynasty that the Yellow River went south to the end of the Qing Dynasty, when the Yellow River rushed south to the Huai River and entered the Yellow Sea, it flooded more than a hundred times in Kaifeng and its neighboring areas, at most once a year, and at least ten years. Since the Yuan, Ming and Qing Dynasties, Kaifeng City had been flooded by the Yellow River water seven times. The most serious time was that Li Zicheng surrounded Kaifeng, and Gao Mingheng, the governor of the Ming Henan, dug up the river embankment northwest of the city, trying to flood the rebel army. The flood rushed into the city from the north gate, and the water was level with the city. The whole city was swallowed by floods, and there were few buildings left in the city, and Kaifeng became a dungeon again.

Such geographical conditions naturally deeply affected the development of Kaifeng City. When the Jin capital Kaifeng, the Bian River could still be partially navigated. By the Ming and early Qing dynasties, there was only one river that could be navigated. The starting point of its shipping was no longer Kaifeng, but moved to its outer port, Zhuxian Town. After the Daoguang of the Qing Dynasty, the Jialu River was also silted due to the repeated flooding of the Yellow River, and Zhuxian Town also declined. Although land transportation was once known as the "Eight Provinces Connecting Yamen", its actual attractions were mainly limited to Henan Province.

At the same time, the silt and sand of the Yellow River also salinized the fertile plain farmland near Kaifeng, to the point where it was "rich and salty, salty and alkali-brine". The result of the destruction of the water transport network also made Kaifeng, which developed first with its water transport hub, inevitably plummeted and reduced to a regional political center. In modern and modern status, it was replaced by Zhengzhou, and the ancient capital eventually became a third-tier city.

Zhao Bing, who had known for thousands of years, had a lucky mentality of Kaifeng, but before he arrived in Kaifeng, the surrounding situation had already made him realize that the old capital was no longer the old capital. In the current military situation, most of the main forces of the Mongol Yuan army around Kaifeng had been annihilated or surrounded, and the remaining were only military farms and a few sanctuary troops. If he continued to move north, there would not be much resistance to recovering the area south of the Yellow River, but he felt that it was not the best time, and seizing Kaifeng would make him carry a huge burden.

First of all, from the military situation, the Eastern Route Army has basically achieved the strategic goals set at the beginning. Although the Western Route Army has arrived in Xiangyang, it has not been able to recover it for a long time. As a result, too many people have emerged in the east, forming a huge protrusion, and many counties in the surrounding areas have not been recovered and consolidated, forming many gaps. If the enemy concentrates its forces and penetrates from the gap to the rear and detours to the rear of the Eastern Route Army, at this time the main forces of the Song army are concentrated on the front line and there is no time to return to aid. Therefore, the Eastern Route Army must at this stage stabilize the newly acquired land, block the gap, and not give the enemy an opportunity to take advantage of it.

On the other hand, the war in Sichuan and Shu is still continuing, and due to inconvenient transportation, the war report cannot be transmitted back in time, which makes Zhao Bing unable to grasp the battle situation in time and makes him dare not act rashly. If the attack on Shu fails, Xiangyang will also face the danger of being attacked from both sides. Zhao Bing launched the Northern Expedition and attack on Shu to improve the defense system in Jiangnan and change the passive strategic situation. Xuzhou, Xiangyang and Chongqing are the three important nodes of the entire defense system. If it is unstable at all, then there will be huge loopholes in the entire system and the danger of collapse.

In addition, Kaifeng is a place of four battles, and it is already a consensus that it is not conducive to defense. After the recovery, a large number of troops were needed to garrison, which inevitably made the Song army, which was already insufficient, lose its strategic mobility. In addition, the military preparations for the continued Northern Expedition were still not completed, and the most important thing was the lack of cavalry. After crossing the Yellow River, it was the North China Plain. It was difficult for an army without mobility to gain an advantage, so Zhao Bing needed time to expand and train cavalry, which took time to do it.
Chapter completed!