In the twentieth year of Jian'an (215), Cao Cao led a major attack on Hanzhong after Liu Bei captured Yizhou, but failed to seize the opportunity to further attack Yizhou, but Cao Cao still left Xiahou Yuan to guard Hanzhong and sent Zhang He to harass the Brazilian area.

For Liu Bei, Hanzhong was the gateway to Yizhou, and he led a large army to personally crusade against Hanzhong at the suggestion of Fa Zheng, Huang Quan and others.

【Battle of Wakou Pass】

In the twentieth year of Jian'an (215), after Cao Cao occupied Hanzhong and returned to Yecheng, Zhang Hebei supervised the armies to attack the two counties of Badong and Brazil controlled by Liu Bei, intending to migrate the local people to Hanzhong to weaken Liu Bei's strength.

At that time, Zhang Fei was the Brazilian Taishou, in order to resist Zhang He, Zhang Fei personally led the army to fight with Zhang He for more than 50 days, and the two sides started a big battle at Wakou Pass. Zhang Fei led more than 10,000 elite soldiers to take the initiative to attack Zhang He of the ditch, Zhang He led the troops to meet the attack, Zhang Fei led Zhang He to Wakou Pass, the mountain road is narrow, Zhang He's army can not be rescued before and after, was defeated by Zhang Fei, Zhang He had to give up his horse to climb the mountain and flee in order to escape, and led more than ten people to flee to Nanzheng. Brazil County has since been secured.

【Advice to go north】

As early as when Cao Cao broke Zhang Lu and Zhang Lu fled into Bazhong, Huang Quan said to Liu Bei: "If you lose Hanzhong, the land of Sanba will be threatened, which will cut off the thighs and arms of Shudi." So Liu Bei took Huang Quan as his protector and led the generals into Bazhong in an attempt to unite Zhang Lu. However, Zhang Lu had already returned to Nanzheng and surrendered to Cao Cao, and Huang Quan returned.

Two years later, in the twenty-second year of Jian'an (217), Liu Bei had stabilized the situation in Yizhou, so Fa Zheng persuaded Liu Bei: "Cao Cao subdued Zhang Lu in the first battle and pacified Hanzhong, but he did not take advantage of this momentum to enter Ba and Shu, but left Xiahou Yuan and Zhang He to guard Hanzhong, and led the army to the north. Now analyzing the talents and strategies of Xiahou Yuan and Zhang He, it is incomparable to the cleverness of our generals, if we raise troops to conquer, we will definitely succeed. After winning, you can vigorously develop production there, accumulate grain, and find an opportunity to send troops to attack, so that you can destroy the enemy and the Han Dynasty, and you can encroach on and occupy the two prefectures of Lu and Liang, open up the territory, and you can stick to the dangerous points, which is a long-term plan to divide one side. This is probably a good opportunity that God intends to give us, and we must not miss this opportunity! Liu Bei agreed with Fa Zheng's strategy very much, so he decided to lead the generals to advance into Hanzhong, and Fa Zheng also went with him, which also marked the official start of the Hanzhong War.

In the same year, Sun Quan sent the commander Xu Shen to ask for surrender, and Cao Cao negotiated peace with Sun Quan, allowing him to concentrate his forces against Liu Bei.

【The Battle of the Lower Division】

After Liu Bei made up his mind to seize Hanzhong, he sent Zhang Fei, Ma Chao, Lei Tong, Wu Lan and others to attack and defend the country, while Cao Cao sent Cao Hong, Cao Xiu, Cao Zhen, Zhang Ji and others to resist.

In the twenty-second year of Jian'an (217), in October, Liu Bei was ready to compete with Cao Cao for hegemony in the land of Hanzhong, so he sent Ma Chao and Zhang Fei, Wu Lan, and Lei Tong, who had just defeated Zhang He in Brazil, to lead the troops to argue, and more than 10,000 people from the seven divisions of Lei Ding of the Di nationality responded to Ma Chao and contained the main force of Cao's vanguard.

In the following year, in the first month, Zhang Fei, Ma Chao, Wu Lan, Lei Tong and others led troops to garrison Fushui, preparing to attack Wudu and Yinping counties. Wu Lan and Lei Tong were defeated by Cao Hong and Cao Xiu, Wu Lan's general Ren Kui died in battle, and King Yin Ping and Wang Qiang beheaded Wu Lan and dedicated his head to Cao Jun.

At that time, Liu Bei led the generals to attack Hanzhong, and sent the general Wu Lan to attack Xiazhong. Cao Xiu was then appointed as a cavalry lieutenant, and together with Yilang Xinbi, he served as the commander of the capital general Cao Hong's army, and joined the army with Cao Zhen, the general of Yongzhou, and Zhang Ji, the assassin of Yongzhou. Cao Cao said to Cao Xiu before the expedition: "Although you are called to join the army, you are actually the commander of this army. After Cao Hong learned of this order, he also entrusted Cao Xiu with the responsibility of military affairs. At that time, Liu Bei saw that Cao's army had advanced to Xiajiao, so he sent Zhang Feitun to be stationed in the Gushan area, claiming to cut off Cao's army's back route.

After Cao Hong and the generals were hesitant to continue the march, Cao Xiu said: "If Liu Bei's army really wants to cut off the rear route of our army, it should act covertly and set up an ambush in secret. Now he bluffed first, indicating that this was just a suspicious plan by Liu Bei and others. Our army should break through Wu Lan as soon as possible while the enemy has not yet assembled a large army. Once Wu Lan is defeated, Zhang Fei's suspicious soldiers will be meaningless, and they will definitely retreat on their own. Cao Hong followed his advice and marched to defeat Wu Lan, and Zhang Fei retreated.

Later, they all protected Cao Hong against Ma Chao and repelled Ma Chao's attack in one fell swoop. After the victory, Cao Hong held a banquet and made the singer wear very thin clothes and step on the drum, and the people present laughed. Yang Fu severely reprimanded Cao Hong and said: "There is a difference between men and women, this is a big festival of the country, how can you let a woman expose her body in front of the public!" Even the defeat of Xia Wei and Shang is not as good as this. So he resigned angrily. Cao Hong immediately ordered the female performer to stop performing, and asked Yang Fu to return to his seat. Everyone present was in awe.

Later, Liu Bei also sent more than ten battalions such as Chen Shi to attack Ma Mingge, trying to cut off the rear passage of Cao's army, but was defeated by Xu Huang, and the Shu army threw itself into the valley, and there were many dead. When Cao Cao heard about it, he was very happy, gave Xu Huang the talisman to command the army, and ordered: "This pavilion road is the throat of Hanzhong, and Liu Bei wants to cut off internal and external ties and seize Hanzhong." The general's move shattered Liu Bei's plan, what a clever plan among the best! ”

In the twenty-second year of Jian'an (217), after Sun Quan and Cao Cao negotiated peace, Cao Cao's main target at that time was no longer Sun Quan, but Liu Bei, whose power grew rapidly, and for Liu Bei, he lost half of Jingzhou after the demarcation of Xiangshui, and urgently needed to make up for the loss, Hanzhong is the gateway to Yizhou, and it is necessary to seize it, and Cao Cao wants to seize Shu, Hanzhong is also a necessary springboard, so for both sides, Hanzhong has become the focus of their contention, and Cao Cao and Liu Bei must have a battle here.

After Cao Cao seized Hanzhong, he was originally on the offensive, but Cao Cao did not seize the opportunity, and did not give Liu Bei a fatal blow, but only sent Zhang He to harass Brazil and Badong, and as Zhang He was defeated by Zhang Fei, the situation began to reverse, and Liu Bei began to turn defense into attack at the suggestion of Fa Zheng and others, and crusade against Hanzhong.

At that time, the main defenders of Hanzhong were Xiahou Yuan, Zhang He and others, so Liu Bei's first wave of offensive did not show all his strength, but also sent Ma Chao, Zhang Fei and others, Zhang Fei had just defeated Zhang He, Ma Chao was also familiar with Hanzhong and Yongliang, and from the perspective of the selection of generals, Liu Bei's choice was not a big problem.

But defense is always easier and simpler than attack, although Zhang Fei defeated Zhang He with the help of geographical advantages, it does not mean that he also broke through the defense of the defenders in Hanzhong, and although Ma Chao contacted Lei Ding and others who were dissatisfied with Cao Cao and were kind to him, there were also pro-Cao Wang Qiangduan to help Cao Cao, and finally Liu Bei's first large-scale attack on Hanzhong failed, and his generals such as Wu Lan and Ren Kui died in battle, Zhang Fei and Ma Chao retreated.

After the failure of the first attack on Hanzhong, Liu Bei learned from his experience, and soon he personally led a large army to crusade against Hanzhong again, vowing to occupy this place.