In the twentieth year of Jian'an (215 AD), Cao Cao defeated Zhang Lu and captured Hanzhong. Hanzhong is connected to the north by the Qinling Mountains and Guanzhong, and to the south is Yizhou, which is the only way to enter Yizhou from Guanzhong. And for Yizhou, because the terrain of the Qinling Mountains is more rugged than that of Daba Mountain, Hanzhong is particularly important to Yizhou and can be called the gateway of Yizhou.
Hanzhong is the throat of Yizhou, the chance of survival, and if there is no Hanzhong, there is no Shu
Cao Cao controlled Hanzhong, and could attack Yizhou from the south at any time. At this time, Liu Bei had just captured Yizhou, and the people's hearts were uncertain, plus he himself was personally leading the public security in Jingzhou, facing the Wu army for the sake of the ownership of Jingzhou, not in Chengdu. Therefore, the hearts of the people in Yizhou were shaken, and they were shocked three times a day.
Liu Bei had no choice but to take the initiative to make concessions to Sun Quan, ceding the three counties of Changsha, Guiyang, and Jiangxia in Jingzhou in exchange for Sun Quan's troops in Hefei to attract Cao Cao's reinforcements, while he himself led his army back to Yizhou to stabilize the situation.
This move was indeed effective, although Sun Quan's attack on Hefei had already been repelled by Zhang Liao before Cao Cao returned. However, Cao Cao was worried about the loss of the Eastern Front, so he rushed back with the main force of Cao's army, leaving only Xiahou Yuan, Zhang Gao and others stationed in Hanzhong. Coupled with Zhang Fei's subsequent defeat of Zhang Gao at Gongqu, the Wei army's threat to Yizhou was temporarily contained, and the situation in Yizhou gradually calmed down.
However, Hanzhong was extremely important to Yizhou, and Liu Bei was always a little uneasy in the hands of others. Therefore, after consolidating the rule of Yizhou, Liu Bei launched an attack on Hanzhong in the twenty-second year of Jian'an (217 AD).
Liu Bei first ordered Zhang Fei, Ma Chao, Wu Lan, and others to march to xiadi, and Cao Cao ordered Cao Hong to attack. The following year, Cao Hong attacked while the Shu army had not yet been assembled, Wu Lan was defeated, Lei Tong and Ren Fu were killed in battle, and after fleeing to Yinping, they were killed by qiangduan, the leader of the Hu clan. Zhang Fei and Ma Chao saw that Cao Hong had already occupied a favorable position, so they led their army back to Hanzhong.
In the twenty-second year, Liu Bei sent Zhang Fei, Ma Chao, Wu Lan, and others to argue; Cao Hong refused. Twenty-three years later, Cao Hong broke Wu Lan and beheaded his general Ren Fu and so on. In March, Zhang Fei and Ma Chao walked to Hanzhong, and Yin Pingqiang beheaded Wu Lan and passed on his head.
Liu Bei was not willing to accept defeat, so he personally led his troops to Hanzhong and ordered Chen Shi to lead more than a dozen battalions of Shu troops into Mamingge Road, hoping to cut off the way for the Cao army in Guanzhong to reinforce Hanzhong. As a result, Xu Huang led his army to launch a fierce attack, defeating Chen Shi, and the Shu army suffered heavy casualties, many of which fell into the valley and died, opening up the traffic between Hanzhong and Guanzhong.
Prepare Chen Shi and more than ten other battalions to stop Ma Mingge Road, shake off the conquest, thieves throw themselves into the valley, and many dead.
It can be said that in the first half of the Battle of Hanzhong, Liu Bei was repeatedly defeated. However, Liu Bei was determined to win against Hanzhong, so after successive defeats, he still refused to retreat, but instead continued to increase his troops, and entered Yangping Pass to confront Xiahou Yuan. In the spring of the twenty-fourth year of Jian'an (219 AD), Liu Bei, at the suggestion of Fazheng, led the Shu army across the river and stationed at Dingjun Mountain, forcing Xiahou Yuan and Zhang Gao to also leave the camp under Dingjun Mountain.
Liu Bei immediately concentrated more than 10,000 elite troops, divided into ten parts, and stormed the eastern wei where Zhang Gao was stationed overnight, and burned the antlers outside the camp. Zhang Gao could not hold on and sent someone to Xiahou Yuan for help. Xiahou Yuan divided half of his troops to rescue Zhang Guo, and Liu Bei took the opportunity to order Huang Zhong to raid the southern wei where Xiahou Yuan was stationed. Huang Zhong led his army forward bravely and launched a fierce attack, but Xiahou Yuan could not resist and died in the rebellion along with Yizhou's assassin Shi Zhao. Zhang Gao was also unable to support himself, and fled with the remnants of his soldiers into Yangping Pass.
In the first month of the twenty-fourth year, prepare to burn the antlers of the deer at night. Yuan sent Zhang Hao to protect the eastern encirclement, and he sent his light troops to protect the southern encirclement. Prepared to provoke a battle, the Gao army is unfavorable. The general of the Yuan Branch was half-assisted, and in order to prepare for the attack, Yuan Sui was killed in battle, and Guo returned yangping.
At this point, Liu Bei grasped the initiative in the Battle of Hanzhong. After that, although Cao Cao personally led an army to reinforce Hanzhong, Liu Bei held the pass and insisted on not fighting, and Huang Zhong and Zhao Yun surprised Cao's army to succeed. Cao Cao was unable to advance, and the grain and grass were increasingly strained, and he could only abandon Hanzhong after several months of confrontation.
It is not difficult for us to see that although Liu Bei won the Battle of Hanzhong, his early losses were not small. Even Zhuge Liang, who remained in Chengdu, felt that the battle of Hanzhong was extremely attritional, and once hesitated whether to continue to send troops to reinforce the front. It was only when Hanzhong was extremely important to Yizhou that Neither Liu Bei nor Zhuge Liang had a choice, so they had to continue fighting.
Liu Bei's clique was originally the weakest of the three families of Wei Shu and Wu, and the mobile troops he could mobilize were only 50,000 or 60,000 people. After the Battle of Hanzhong, even fewer troops could be used.
Although Cao Cao lost the general Xiahou Yuan, he did not fight much with Liu Bei after he arrived in Hanzhong, but mainly faced off, and the main force of the Cao army under his command suffered little loss. Moreover, after Cao Cao withdrew from Hanzhong, he stayed in Chang'an for a long time. It was not until Guan Yu's northern expedition to Xiangfan, flooded the Seventh Army, defeated Cao Ren and Yu Ban, and was shocked by the great power, and Luoyang was in a hurry, that he left Chang'an.
Therefore, Liu Bei's own losses in the Battle of Hanzhong were not small, and it was a tragic victory. The main force of the Cao army was not attacked, and Guanzhong was heavily guarded. At this time, the strength of the two sides may still be inferior to Liu Bei. Even Guan Yu's Northern Expedition to Xiangfan, Liu Bei could not mobilize his strength, let alone directly attack Guanzhong.