In order to fight against Cao Cao, Yuan Shao was also actively preparing to win over the princes in the south, and he sent envoys to unite Jingzhou Mu Liu Biao and Nanyang Taishou Zhang Xiu as foreign aid. Then the left general Liu Bei also betrayed Cao Cao and seized Xuzhou and Yuan Shao united.

【Liu Biao and Zhang Xiu】

Liu Biao, as Yuan Shao's old ally, did not refuse Yuan Shao's request for help, but he only agreed on the surface, but in fact he was ready to watch from the sidelines, neither prepared to offend Cao Cao, nor did he want to fall out with Yuan Shao.

And Zhang Xiu fought with Cao Cao several times, and once betrayed Cao Cao, killed Cao Cao's eldest son Cao Ang and the love general Dian Wei, and there was no contradiction with Yuan Shao, it can be said that Zhang Xiu should have been Yuan Shao's natural ally, and Zhang Xiu's Nanyang is close to Xuchang, if Yuan Shao gets his support, then the odds of victory in the crusade against Cao Cao can be increased by at least two percent.

But this matter was finally made yellow by Jia Xu. At that time, the war between Yuan Shao and Cao Cao was on the verge of breaking out, and the two sides had already started a confrontation in Guandu, because the enemy of the enemy was a friend, so Yuan Shao sent someone to win over Zhang Xiu, and wrote a letter to Jia Xu asking for mutual assistance. Zhang Xiu originally wanted to promise Yuan Shao, but Jia Xu publicly said to Yuan Shao's envoy in front of Zhang Xiu: "Go back and thank Yuan Benchu for me, brothers can't accommodate each other, can they still accommodate the world's talents?"

Well, Jia Xu directly rejected Yuan Shao's request for Zhang Xiu, and Zhang Xiu was very frightened when he heard it, and said to Jia Xu: "How can you say such a thing?" But it was difficult to recover the water, and Yuan Shao's wooing of Zhang Xiu ended in failure.

In history, Jia Xu not only made Yuan Shao fail to win over Zhang Xiu, but also made Zhang Xiu turn to Cao Cao's side again.

After Yuan Shao's envoy left, Zhang Xiu asked Jia Xu privately about this matter: "Like this, who should we belong to?" Jia Xu's words surprised Zhang Xiu: "It's better to belong to Cao Gong."

Zhang Xiu was very confused and asked: "Yuan is strong and Cao is weak, and we were enemies with Cao Gong, why should we obey him?" Jia Xu said: "This is exactly the reason for returning to Cao Gong. Yuan Shao is strong, and if we attach ourselves to him with such a small number of people, we will definitely not value us. Cao Gong's team is weak, and he must be happy to get us, which is the first reason for joining Cao Gong. Cao Gong acted in the world under the orders of the Son of Heaven, which is the second reason why he should be subordinated to Cao Gong. The third reason is that a person who has the ambition to become a king and dominate will give up his personal grudges in order to show his virtue to the world. I hope you don't hesitate any longer, General! ”

As a result, after Jia Xu rejected Yuan Shao on behalf of Zhang Xiu, he listened to Jia Xu's advice and led his troops to join Cao Cao.

And Cao Cao really did as Jia Xu said, smiling and hating. Cao Cao was very happy to see them, took Zhang Xiu's hand, attended the banquet together, let his son Cao Jun marry Zhang Xiu's daughter, and named Zhang Xiu as the general of Yangwu. Later, Cao Jun's son Cao Wan succeeded Cao Ang.

Cao Cao also took Jia Xu's hand and said, "The person who makes me respected and trusted in the whole country is you!" Shangjuan invited Jia Xu to be the ruling Jinwu, named the Marquis of Duting, and promoted to Jizhou Mu.

At that time, Jizhou had not yet been pacified, so Jia Xu stayed in the military staff of the Sikong Army.

After Zhang Xiu defected to Cao Cao, it was equivalent to making Xuchang less of a big threat, but it strengthened the comprehensive strength of Cao Cao Group.

【Liu Bei and Xuzhou】

In the fourth year of Jian'an (199), Liu Bei betrayed Cao Cao, marched to Xiapi, killed Xuzhou Assassin Shi Chezhou, and captured Xuzhou, after which Liu Bei and Yuan Shao formed an alliance to deal with Cao Cao together, in addition to Dong Cheng and others were also ready to move in Xuchang.

Cao Cao once sent his subordinates Liu Dai and Wang Zhong to attack Liu Bei, but they were all repulsed, and Xuzhou once again became Cao Cao's confidant.

In the fifth year of Jian'an (200), the "Edict of Clothes and Belts" incident, Cao Cao eradicated Dong Cheng and others, and learned that Liu Bei was also involved, so he finally decided to crusade against Liu Bei first to eliminate future troubles. At that time, Yuan Shao was already prepared for a decisive battle with Cao Cao, so it was very likely to take advantage of the situation.

After learning that Cao Cao attacked Liu Bei, Tian Feng, a strategist under Yuan Shao, immediately said to Yuan Shao: "It is Cao Cao who is fighting with you for the world, and Cao Cao is now going to the east to attack Liu Bei, the battle between the two sides cannot end quickly, now mobilize all the troops to attack Cao Cao's rear, and it can be pacified as soon as you go." The army is dispatched according to the timing, and now is the time. ”

However, Yuan Shao shirked the matter on the grounds that his youngest son was ill, and sat back and watched the opportunity slip away, and Tian Feng's strategy was not adopted in the end. At that time, Tian Feng was extremely angry because of Yuan Shao's hesitation, and he knocked on the ground with his crutch and said, "It's over!" It's a pity that I finally caught up with such an opportunity, but I lost the opportunity because of the child's illness! Yuan Shao was very angry when he heard it, and since then he has alienated Tian Feng.

Liu Bei was then defeated by Cao Cao and fled north to join Yuan Shao. Yuan Shao missed a great opportunity to eliminate Cao Cao in advance.

At that time, Cao Cao was not on the front line of Guandu, although he would be prepared, but Cao Cao's army, which lacked the backbone, could not resist the main army led by Yuan Shao, even if Yuan Shao could not take the opportunity to completely eliminate Cao Cao and recapture the Son of Heaven, taking a step back would cause great pressure on Cao Cao, forcing him to give up the crusade against Liu Bei and return to the army to rescue.

As long as Liu Bei threatens on the flank, Cao Cao will not be able to confront Yuan Shao with all his strength in the front, and must allocate a considerable part of his forces to deal with Liu Bei, and Xuzhou, where Liu Bei is located, is connected to Yanzhou and Yuzhou under Cao Cao's control, Cao Cao is not very good at defending against Liu Bei, Liu Bei can support Yuan Shao to go north to Guandu, or he can directly send troops to Xuchang to capture Emperor Xian, these can be right

Cao Cao posed a very big threat.

And Cao Cao also understood this, so when he attacked Xuzhou this time, he tried to fight as quickly as possible, without giving Yuan Shao more time to think about it, nor did he give Yuan Shao the opportunity to support Liu Bei, while Yuan Shao let the possible victory slip out of his hands because of his hindsight.

In history, during the Battle of Guandu, although Yuan Shao contacted many allies such as Liu Biao, Zhang Xiu, and Liu Bei, the effect was not great. Although Liu Biao favored Yuan Shao, he did not give specific promises, and was actually a neutral; And because Zhang Xiu was weak, Yuan Shao's attention was still a little insufficient, and finally Jia Xu brought Zhang Xiu to Cao Cao's side; Liu Bei was Yuan Shao's natural ally, but Yuan Shao ultimately failed to seize the opportunity and sat back and watched his ally be wiped out by Cao Cao.

Therefore, when Yuan Shao fought a decisive battle with Cao Cao Guandu, Yuan Shao could not get the support of the other princes, so he had to go out in person and prepare to completely eliminate Cao Cao from the front.