The forces that could cause intrusion to the northern frontier of Wei were the Liaodong Gongsun clan, Wuhuan, Xianbei and the Xiongnu.
Among them, the Xiongnu were divided into five internal tribes during the period of Wei Wu and Cao Cao, and they were no longer in danger.
Wuhuan, the three counties in the east, was conquered by Wei Wu and Cao Cao and moved inward. Daibei Wuhuan was conquered and destroyed by Cao Zhang. The only leader who had the chance to escape to Mobei, Gu Jin, was later beheaded by Tian Yu, and the tribe began to decline.
As for Xianbei, the western part fell into civil strife and was unable to invade the territory; the eastern leader Suli first defeated Tian Yu in five battles, and then was forced to be attacked by Ke Bineng, so he chose to annex Wei and lost his power; in addition, Xianbei in the central part Ke Bineng was killed now, and the whole Xianbei fell into aggression against each other. From then on, there was little trouble in Monan.
The Gongsun family in Liaodong has also been destroyed.
In other words, with the end of the Battle of Liaodong and the Battle of Pingcheng, Wei's northern border ushered in a long-lost peace.
Cao Rui finally had a stable rear, and he was free to mobilize more troops and have a steady stream of supplies to fight against Han and Wu.
But he didn't have enough time to prepare.
When he ignored the objections of Duke Gungun due to frequent wars and the long hard labor of the Li people, and decided to support the Great Sima Cao Zhen, who would use the power of Guanzhong and Hexi to fight against Shu, Soochow also sent troops.
After many losses at sea and numerous harvests, Sun Quan finally returned his sights to land.
In particular, in recent years, the Han Dynasty had frequently sent troops and reported good results, but Soochow had no achievements to speak of except the Battle of Shiting, which made him very worried.
When the Three Kingdoms stood in a tripartite state, Wei was the dominant one, while Han and Wu were both weak.
He didn't want to see the Han and Wei Dynasties becoming divided in the future, while the Soochow family was weak.
Therefore, from the end of spring to the beginning of summer, he began to prepare for the Northern Expedition.
It just so happened that in mid-June, the Prime Minister of the Han Dynasty, Zhuge Liang, sent an envoy for the first time to invite him to implement the alliance to jointly attack the Wei Dynasty.
When the military report of the capture of Manyin City reached Longyou, the prime minister began to prepare for Wei's attack.
No matter what, it was impossible for the Wei State to just sit back and watch the Wanyin Sui fall into the hands of the Han Dynasty.
Because if Hui Yinsai is not captured, Liangzhou will be cut off from Guanzhong - when the prestige of Luoyang cannot be conveyed, Liangzhou cannot be defended.
Even the Wei State has adopted the policy of "people on the border govern the border".
After all, there are only a few counties in the Hexi Corridor, which can only benefit a few people.
However, there are many leaders of Haoyou and Qianghu tribes in Hexi, and it is impossible for everyone to benefit equally.
Those who cannot benefit from sharing the profits, or who feel that the benefits are too small, will want to redistribute the profits when the Wei State cannot pose a threat to the Hexi Corridor and the Han army comes.
The Han army entering Hexi was like a fire, igniting the ambition in the hearts of countless people who were uneasy about the current situation.
Break the old order, reshuffle power, and change the pattern of interest distribution.
The new nobles are destined to rise on the corpses of the old nobles.
Even an illiterate horse bandit leader knew this well and would be willing to provide information to the Han army and become a pawn in order to gain an official position.
And what will happen to the Wei State after losing Liangzhou?
In less than five years, the Han Dynasty will sweep through Guanzhong with thousands of cavalry; and once the Han Dynasty invades Guanzhong, it will have the foundation of the powerful Qin Dynasty that swept the six countries.
There is something even more frightening - once the Han Dynasty returns to Chang'an, it will also be a kind of fire that ignites people's hearts.
That means: Han Zuo is not dead!
Wei's founding period was too short, and it was unable to withstand the four hundred years of Han Dynasty's accumulated prestige.
That is a long-standing belief in people's hearts. It can only be slowly diluted by the accumulation of time, and cannot be eliminated by setting off one or two "Wei Xi cases".
Wei Guo knew this very well.
Therefore, they will do their best to stop the root cause of all this and take back the last link that shows Liangzhou belongs to the Wei State!
In this regard, the Prime Minister also has a clear understanding of fire.
Therefore, he sent envoys to Jiangdong to ask Sun Quan to send troops to attack Wei and reduce Wei's troops to attack Longyou.
For example, the army of Wei State guarding Luoyang was restrained from coming to Longyou.
The Han Dynasty took the initiative to send troops to attack in consecutive years, and its reserves were consumed too much.
If Soochow sends troops, no matter what the outcome is, even if it only allows Wei to transport less material to Guanzhong, it will be beneficial to the Han Dynasty.
For this reason, although the prime minister had long known that Soochow was preparing to send troops to attack Wei, he still gave him many benefits.
Mainly in the war horse trade.
Sun Quan thought that there were too many soldiers lost in the sea, so he had already used the Shanyue prisoners to supplement his army and farmland, claiming that he would not exchange the prisoners for war horses. He also asked the Han Dynasty to send troops to attack Wei, and there was not much food for trade.
They were allowed to use water essence, pearls and other extravagant and unrealistic materials to offset part of the trading grain.
All these prime ministers agreed.
He also regarded the two countries as allies and sent more than ten Qiang and Hu herdsmen to Soochow to teach them how to properly care for their war horses.
Then, there was a vague mention in the letter of credence: Most of Wei's troops will come to attack Longyou. There will not be too many troops to fight against your country. Don't let it end like the last time you sent troops to attack Wei.
After seeing this, Sun Quan felt a little angry.
But he didn't refute the reason for being looked down upon by the big man.
In any case, the last time he personally led the army out of Huaiyou, he only killed a few hundred people under the command of Wang Ling, the governor of Wei Yangzhou, and then withdrew because the plot was leaked.
Therefore, Jiangdong used a lot of troops this time, and he was very decisive in winning a battle.
Moreover, they did not wait for the Han-Wei-Longyou War to break out beforehand, so they took the lead in sending troops in early July of Xia Dynasty.
The troops were divided into three groups.
All the way is Jingzhou.
Lu Xun and Zhuge Jin led the army from Xiakou up the Han River to attack Xiangyang.
Along the way, with Sun Shao as the chief general and Zhang Cheng as the deputy general, they entered Guangling County, followed the Zhongxiaodushui Canal, and marched towards Huaiyin.
The two groups of soldiers and horses each numbered more than 10,000 people, and they were mainly for support, in order to disperse Wei's garrison strength.
The main force was the 100,000-strong army led by Sun Quan himself, who set out from Ruxukou to capture Hefei.
The route of these three armies and horses was almost the same as the formations and routes used by Wei Wen and Cao Pi when they first attacked Wu. The difference was that this time it was the northern expedition of Dongwu instead of the southern expedition of Cao Wei.
The results of the battle seemed to show some signs of development toward Cao Pi's failure.
Needless to say, the two groups, Lu Xun and Sun Shao, each led more than 10,000 men. They neither dared to go too deep nor took a chance. They were restrained by Sima Yi who rushed back to Jingzhou and Wang Ling, the governor of Wei Yangzhou.
But after the main force led by Sun Quan personally arrived at the battlefield, they did not get off the ship for more than 20 days!
The reason is that Man Chong gave him a difficult problem.
Man Chong believed that the Wei State had invested too much troops in the northwest front, and concluded that Soochow, which was allied with the Han Dynasty, felt that there was an opportunity and would lead a large army to attack Huainan. Therefore, he sent a request to Luoyang very early to build a new city of Hefei.
The former Hefei City, located on the Nanfei River, was built by Liu Fu, the governor of Yangzhou, thirty years ago. It has survived many wars and has never been captured.
However, Man Chong felt that the location of Hefei City would be disadvantageous to Wei in the war.
The navy in the east of the Yangtze River could go up the Nanfei River directly to the city. If defeated, they could quickly retreat by boat, which can be said to be easy to advance and retreat.
Moreover, he felt that Jiangdong was just an elite naval force. If he went ashore to fight in the field, he would not be able to compete with Wei.
Therefore, he wanted to move Hefei City to the north of Nanfeishui River.
At that time in Luoyang, this table still caused endless debate.
For example, Jiang Ji, who was well versed in Jianghuai military affairs, clearly held opposing views.
Thinking that Hefei City was not captured by Jiangdong, but would be destroyed by our own people, such a proactive concession would make the army officers and soldiers think that Wei was unable to fight against Soochow because of the northwest front.
But in the end, Cao Rui and many courtiers still chose to believe Man Chong's judgment.
Therefore, when Sun Quan led his army upstream, he found that the old Hefei City was in ruins and the new Hefei City was thirty miles away.
If you want to attack the city, you have to leave the shore and go north for thirty miles.
The distance was too far, causing him to fall into a battle between heaven and man.
If they were to advance, they would have to worry about whether the Wei State would ambush along the way, or use the mobility of the cavalry to raid the fleet remaining on the Nanfei River, leaving the army with no way to return.
But if we do not march, we may damage the morale of the soldiers.
When a large army comes with great morale, they can't just retreat in despair without firing a single shot, right?
Therefore, after he sent Quan Cong to lead a partial division to attack Liu'an, he has been in a dilemma. He failed to make a decision and stood still for twenty consecutive days.
However, as far as the Han Dynasty was concerned, it didn't matter whether Sun Quan went ashore thirty miles to attack the city.
In the heart of the prime minister, he had never hoped that Jiangdong would still be as brave as Sun Ce in the past, advancing with great success and defeating Wei Wei.
Sun Quan sent so many troops that he had already restrained the Han.
For example, Sima Yi, who was stationed in Jingzhou, did not dare to lead his army from Xicheng to harass Hanzhong County.
For example, the army that had just returned to Luoyang from the Liaodong expedition showed no signs of entering Guanzhong.
On the contrary, it is said that the news coming from Xizuo seems to be that Cao Rui plans to lead an army to Huainan to fight Sun Quan in order to solve the problem of Wei Yangzhou's shortage of troops.
However, Cao Zhen's current military strength cannot be underestimated.
In the sixth month of summer, Tuoba Liwei of Xianbeisuo sent his eldest son Tuoba Desert Khan to Luoyang to accept an official position in Wei as a hostage, and then began to migrate. At the end of July, he crossed Beidi County and entered the northern part of Anding County. , becoming the barrier in the central and northern parts of the Wei Pass.
This allowed Cao Zhen to use up all the garrison strength of the three auxiliaries in Guanzhong, about 70,000.
Furthermore, on the grounds that there was no war in northern Xinjiang, Cao Rui ordered part of the garrison troops from Jizhou, Bingzhou, Sizhou, Hedong and Hanoi counties, totaling about 30,000, to transport grain and baggage to Guanzhong, under Cao Zhen's control.
It is worth mentioning that the Southern Huns who were included were also conquered by Wei.
In the old days of Wei Dynasty, Cao Cao divided the Southern Huns into five tribes. He left Shanyu Huchuquan in Luoyang as an official, and ordered King Youxian to go to Beidai to lead the tribe. Therefore, the Southern Xiongnu had always been at peace with Wei. This time they were conquered. , with Zuoxian Wang Liu Bao (son of Yu Fuluo and nephew of Shanyu Huchuquan) as the commander-in-chief, he led more than 6,000 Huns cavalry to Anding County to join the expedition.
In other words, excluding Liangzhou's military strength, Cao Zhen alone commanded 110,000 infantry and cavalry!