The occurrence of the 'howling battalion' indicates that the army has suffered a catastrophe, and when the army bombs the camp, in order to avoid disaster, the troops generally take a defensive position and cancel all offensive plans. But it is also often considered a special paranormal event, a bad omen. Therefore, after learning that Xuyi City had a roaring camp and caused the loss, Sizhou was also affected by the incident, and the Song army took the opportunity to capture it, everyone in the palace had a feeling of imminent disaster in their minds, and the loss of Sizhou City also shocked the Zhenjin ministers.

The reason why the loss of Sizhou shocked Meng Yuanjun and his ministers had to start with the Grand Canal that ran through the north and south. After the opening of the canal in the Sui Dynasty, it became a transportation artery connecting the north and the south, and it was also the economic lifeline of the Central Plains Dynasty. With the increasing economic status of the Yangtze River Basin, the formation of the confrontation between Song and Liao and Song and Xia, and the implementation of the policy of "guarding the inside and the outside" of the Northern Song Dynasty, the north-south water transport is of greater significance.

On the basis of the transformation and dredging of the original waterways of the previous generations, the Song Dynasty relied on the canal to form an artificial water transport system that radiates to the capital Kaifeng as the center. The Bianhe River is one of the "four rivers of Caoyun", that is, the Tongji Canal, and the route is basically unchanged. To the west of Kaifeng, the Yellow River flows eastward from Biankou, Heyin County, enters the water gate of the Guo Bian River outside Kaifeng Prefecture, passes through the inner city, and goes out of the city from the water gate of the Guo Bian River outside the city. The section of the river east of Kaifeng is roughly along the general trend of the Huiji River today, and enters the Huai River in the south of Sizhou City.

Therefore, the Song Cao River leads the river and lake, makes the best of the South China Sea, the wealth of half the world, and the department stores of the mountains and rivers, all enter from the Bianlu, so that the Bianhe River is the "foundation of the founding of the country". The city of Sizhou was built in the Northern Zhou Dynasty, destroyed in the Sui Dynasty and rebuilt in the Tang Dynasty. The city is located in the lower reaches of the Huai River, the mouth of the Bianhe River, which is the throat of the Central Plains region and the key point of controlling the north-south traffic, and the importance of its political, economic and military status cannot be ignored.

After the Song Dynasty crossed to the south, it was a corner of peace. The capital of Jin State is in Yanjing, and the capital of Beijing is to Yangcao Shandong and Hebei. When the Yellow River flows south, the Bianhe River and the Guangji River are silted up one after another, and the grain is transferred only according to the people and the Yuhe. Due to the Yellow River's repeated flushing and shallow flow of the bed, Sejong and Zhangzong ordered the officials of Hezhou County to bring control and manage the affairs of the Cao River.

Yongji Canal is the old road for a long time, Dading 11 years to open Jinkou, channel the Lugou River to the north of the capital into Hao, and east to the north of Tongzhou into Lushui. Set the sluice gate to save the Gaoliang River and the White Lotus Pond, and want to borrow the water of the Lugou ditch to turn the water. However, due to the high terrain, the water of the Jinkou River is turbid and cannot win the boat, and it is still held by land. In the fourth year of Taihe, the state Lushui canal was opened, the sluice gate was built to save water, and the slope drop was slowed down, and finally the Yuhe Cao boat traveled to the lower part of the capital.

In the fourth year of Zhenyou, he opened the water into the royal river for feeding; In addition, Jin also opened a canal in the northeastern suburbs of Zhongdu to open the Wenyu River; Open a long straight ditch through Wan'an Lake in the territory of Lingbi County, Anhui Province today, connecting Bian, Si, all want to pass Caosu. The Jin Dynasty did not have a long period of national transportation, so the canal was not used for a long time, but after the Jin Dynasty's governance, some canals that were about to be silted up were revived. It is placed in the counties along the Yuhe River respectively, set up a gang boat, and set up two ships in spring and autumn, and store them in Tongzhou and Zhongdu Tongji, Fengbei, Fengzhen, Guangji and other warehouses, and transport nearly one million stones of grain per year.

After the destruction of the Jin by the Meng Yuan, Kublai Khan succeeded to the throne of Khan and began to build the capital. In the second year of Zhongtong, Guo Shoujing was on the water conservancy article Chen Liutiao, one of which was to propose to divert water to the Zhongdu of the Jin Dynasty, east to the old Cao River in Tongzhou, and south to open the river to Yang Village, but between Tongzhou and Dadu fifty miles, the water source is lacking, and land transportation is still needed.

After that, Mengyuan pacified the south of the Yangtze River, still relied on the old canal for water and land transshipment, its route is: from the Yangtze River to the Huai River, against the Yellow River up to the Zhongluan dry station, land transport 180 miles to Qimen, into the Yu River, and then ship to Dadu. This old canal road since the Sui and Tang dynasties, because of the changes, has not been smooth for a long time, and there are many inconveniences in transportation, so the Yuan Dynasty government began to build the Grand Canal one after another.

In the 18th to 20th year of the Yuan Dynasty, Oluchi presided over the diversion of Wenshui and Surabaya, and dug a Jeju River in 150 townships from the northwest of Jeju to Suseong Ansan. Cao Road into the Huai River into Surabaya, Economic Prefecture Hebei Da'an Mountain, out of the Daqing River, through Dong'e, Lijin into the sea, and then by sea into Zhigu Dadu. After that, due to the siltation and congestion of the sea, the transportation channel was impassable, and it was transported from Dong'a Lu to Linqing into the Yuhe River. So far, the north-south shipping of the Yuan Dynasty has been roughly communicated, and the only one that is not passed, is only one or two hundred miles of dry road between Dong'e and Linqing.

If according to the development of history, the Mengyuan Dynasty formed a method of attaching equal importance to shipping, land and sea and river transshipment at this time, and basically solved the problem of water transportation. But after Kublai Khan's violent death, Zhenjin succeeded to the throne, Zhao Yu recovered Jiangnan, and defeated the Mengyuan naval army, so that it lost the right to control the sea, and the sea was cut off again. However, after the loss of Jiangnan, the canal no longer undertook the task of transshipment grain from Jiangnan, and its dependence on the canal was slightly reduced.

However, when Mengyuan lost Jiangnan, he not only lost the heavy tax land, but also lost the salt fields along the coast of Jiangsu and Zhejiang, and his dependence on salt in the Lianghuai region became increasingly serious, and the transportation capacity of Cao Yun was insufficient. Therefore, Zhenjin adopted the suggestion of Yin Han Zhonghui and others in Shouzhang County, and sent Li Chuxun to preside over the excavation of the Huitong River, starting from the southwest of Anshan, and dividing the water source of Liangshan Luo to flow north. Northwest to Dongchang through Shouzhang, and northwest to Linqing into the Yuhe. It was 250 miles long and took six months to complete.

At the same time, last year was ready to accept Guo Shoujing's suggestion to channel the Shenshan Spring in Baifu Village, Changping County, cross the Shuangta and Yuhe River, lead one acre and Yuquan water to the west gate of the capital into the city, and then go southeast out of the Wenming Gate to Tongzhou Gaolizhuang into the Baihe River, so that the canal can be opened up to the last 'one kilometer' of the city, so that the boat can always drive into the capital. In this way, it can not only speed up the transshipment, save manpower, and can also transport troops to the front line by water if there is a war between the two Huai, but now the project has not yet been completed, and the Song army has begun to fight for the two Huai.

However, Mengyuan has basically completed the diversion project of the Grand Canal, forming the Tongzhou Grain River that flows from Tongzhou to the south to the Dagu River and connects to the Yuhe River in the southwest; From Tianjin south to Linqing, it will meet the royal river of Tonghe; Ansan from Linqing to Suseong, Dongpyeong Road, Huitong River connecting Jeju River; From Ansan in Suseong to Jeju, the Jeju River connects Surabaya into the Yellow River; The Yangzhou Canal that flows from the Yellow River to Yangzhou into the Yangtze River. Then it is connected with the Jiangnan Canal from Zhenjiang through Suzhou and Jiaxing to Hangzhou occupied by the Great Song Dynasty, forming the Beijing-Hangzhou Grand Canal that runs through the north and south for a whole length of 3,000 miles.

At present, the Song army now occupies Xuyi, which indicates that its troops have touched Huaibei and pointed at the Central Plains. Moreover, the Song army's occupation of Sizhou was equivalent to controlling the northward passage of the old canal, and they could use this to mobilize troops and drive directly along the river to Kaifeng, Luoyang, and even Xi'an, threatening the core area of the Central Plains of the Mengyuan Dynasty. Zhenjin and others all believed that with the powerful naval army and transportation capacity of the Southern Dynasties, controlling the canal was equivalent to grasping the key to fighting for the gate of the Central Plains. So the loss of Sizhou has reversed the situation again......

"Is there a Song army in the direction of Shanyang?" After a while, Zhenjin, who had calmed down a little, asked in a trembling voice.

"Great Khan, the Song army from Yangzhou divided its troops in Gaoyou into two routes, one was to Xuyi by land, and the other was to go straight to Shanyang by water. According to the latest battle report, the Song army was only a day's voyage from Shanyang. Yuechi Cha'er said.

"What? Only one day trip! Zhenjin was shocked, he knew that it would take a day to reach Dadu at the fastest speed of the stagecoach, and now the Song army had already arrived at Shanyang City in terms of time, and it was too late to send reinforcements. His face was contorted into a ball of pain, and he whispered with his palm on his forehead.

"Great Khan, Shanyang enters the Huai River for the new canal, and goes north to the Kongdao of the Central Plains, we must not lose it, and we must send reinforcements as soon as possible!" An Tong was also in a hurry. He knew that Shanyang is located in the core area north of the Gaoguan River in Jiangsu, adjacent to the river and the sea, in the center of Xuzhou, Haizhou, Nantong Prefecture and Yangzhou, facing the sea in the east, followed by the Jianghuai Plain in the west, and there are two big rivers in the north of Huai and Si, which are the main transportation routes for the south and north.

"Don't be anxious, the capital of Shandong and Hebei moved to Shanyang in the previous year, most of them followed Yuxi Timur's southern expedition, but there are still thousands of Hongze Tuntian left, they have moved to the city to guard, even if they can't win, they can also block the Song army. We can quickly mobilize the guards and pro-army to rush to the aid of the enemy in Huainan! Yue Chi Cha'er saw that Zhenjin's face was extremely ugly, and knew that he was worried that Shanyang would be lost, and the Song army's two armies would be able to penetrate deep into the belly of the Central Plains, so he spoke again.

"Great Khan, I thought that at present, the Song army is attacking everywhere and sending reinforcements from all over the army, which is not only difficult to stop the enemy's northward advance, but also may be broken by the enemy. At this time, Sang Ge also suggested.

"Nonsense, if you surrender the Central Plains to the enemy army, wouldn't it ruin the decades of hard work of the ancestors, is it true that Zuo Xiang wants to be the sinner of the Great Yuan through the ages?" An Tong roared angrily when he heard this.

"That's not what I meant, but I was worried about the Khan's safety. Now the Song army is strong, and our army can only fight the guards of the Gongwei Beijing Division, once they are transferred, most of them will no longer have any fighting soldiers, and if they are defeated all the way, they will be taken advantage of by the enemy. But there are still tens of thousands of elite horsemen of our clan in Shangdu, and they will attack again in one place, repeating the Central Plains at their fingertips, rather than trying to get away with it for a while! Sango argued.

"Retreat and behead!" Ye Li also snorted coldly at this time, "Great Khan, the Central Plains cannot be lost, this is the fundamental place in the world, if we lose the Central Plains, we will lose all food and taxes, and I am afraid that iron weapons are rare." At that time, how can we talk about recovering the Central Plains? ”

"Exactly, the Central Plains cannot be lost, and the two Huai cannot be lost, otherwise even if I pass away, I will not be able to see the ancestors and the ancestors again!" Listening to the quarrel, Zhenjin slapped the case in a loud voice with great irritability......