Why Liu Bei and Cao Cao Fought for Hanzhong

Yi Province gave Liu Bei a base.

Hanzhong would decide whether that base was secure.

Zhang Lu Held Hanzhong

Hanzhong had long been held by Zhang Lu.

Zhang Lu's grandfather, Zhang Ling, later honored as the Celestial Master, founded the Way of the Five Pecks of Rice. By Zhang Lu's time, this was not only a religious movement. It had become a local governing structure in Hanzhong.

Zhang Lu set up charity lodges where travelers and poor people could take rice and meat. Religious leaders also helped administer local affairs. Hanzhong became a kind of combined religious and political community.

His power also came from Yi Province politics. Liu Yan had once hoped to use Zhang Lu's followers and appointed him to attack Hanzhong. Zhang Lu took the region, killed Zhang Xiu, who had gone with him, and held it himself.

After Liu Yan died, Liu Zhang became more hostile to Zhang Lu. The two sides fought for years.

Someone once urged Zhang Lu to declare himself king, but Yan Pu warned him not to. Hanzhong had strong terrain and enough people. If Zhang Lu formally honored the court, he could preserve wealth and rank. Claiming kingship too early would make him a target.

Zhang Lu listened.

For years, he kept Hanzhong under a court-facing cover, not rushing to become king or expand too far.

But Hanzhong was too important. After Cao Cao pacified the north, he could not tolerate it forever.

Cao Cao Took Yangping Pass

In 215, Cao Cao personally campaigned west against Zhang Lu.

When Cao's army reached Yangping Pass, it discovered the position was harder than expected. The mountains were steep, the defenses strong, and Zhang Lu's brother Zhang Wei guarded it with tens of thousands of elite troops. Pang De was also there.

Cao Cao could not break through by force. His soldiers suffered losses and food grew tight. He even considered withdrawing.

Then, just before the retreat, Cao's troops lost their way at night while coming down the mountains and wandered into Zhang Wei's camp. Zhang Wei's men had held the pass for days and relaxed their night guard. The lost Cao troops suddenly broke into the camp and threw it into disorder.

The victory came almost by accident.

Xiahou Yuan and Xu Chu followed up, and Cao Cao pushed forward. Zhang Wei fled in the night. Yangping Pass fell.

Pang De surrendered to Cao Cao after this battle.

When Zhang Lu heard that Yangping Pass had fallen, he knew Hanzhong had lost its shield and withdrew toward Bazhong. His followers wanted to burn the treasuries. Zhang Lu refused. He said he had always intended to submit to the court, and the stored goods belonged to the state.

Cao Cao entered Nanzheng and saw the stores sealed. He admired Zhang Lu. In the eleventh month, Zhang Lu surrendered with his family. Cao Cao came out to receive him, made him General Who Guards the South, and granted him a marquis title.

Hanzhong was now Cao Cao's.

For Liu Bei, who had only just taken Yi Province, this was worse than before. Zhang Lu had been a regional buffer. Cao Cao's generals now held the northern gate of Shu.

Hanzhong Pressed Down on Yi Province

Hanzhong guarded the north of Yi Province.

Huang Quan had already warned Liu Bei that if Hanzhong was lost, Ba, Baxi, and Badong would be hard to hold. It would be like cutting away Shu's gate.

Liu Bei sent Huang Quan to receive Zhang Lu, but Zhang Lu had already surrendered to Cao Cao before he arrived.

Cao Cao left Xiahou Yuan and Zhang He to guard Hanzhong, then returned north. Zhang He soon attacked Baxi, trying to move its population into Hanzhong.

Zhang Fei led more than ten thousand elite troops against him. The two sides faced each other for more than fifty days. The mountain roads were narrow, and Zhang He's front and rear could not support each other. Zhang Fei defeated him.

Baxi was saved for the moment, but Hanzhong remained in Cao Cao's hands. As long as Cao's army could descend from there, Yi Province was under pressure.

Liu Bei could not simply sit in Chengdu with the northern door held by someone else.

Fa Zheng then urged him to attack Hanzhong.

Fa Zheng judged that Cao Cao had taken Hanzhong but had not immediately attacked Ba-Shu. Instead, he left Xiahou Yuan and Zhang He behind and returned north. That meant Cao Cao had constraints elsewhere and could not put all strength into the western front.

If Liu Bei acted now, he could take Hanzhong, expand farming, store grain, advance toward Yong and Liang when conditions allowed, and withdraw behind strong terrain when needed.

Liu Bei accepted the plan.

Liu Bei Went North

Liu Bei attacked Hanzhong, sending Zhang Fei, Ma Chao, Wu Lan, and others into the campaign.

Cao Cao's side sent Cao Hong to resist.

When Cao Hong prepared to attack Wu Lan, Zhang Fei loudly claimed that he would cut the Cao army's rear. Cao's generals hesitated.

Cao Xiu saw through it. If Zhang Fei truly planned to cut the rear, he would hide the movement. The louder the threat, the less likely it was real.

Cao Hong accepted Cao Xiu's advice and quickly defeated Wu Lan. Zhang Fei and Ma Chao withdrew.

Liu Bei's first advance did not go smoothly. Cao Cao's western commanders were still dangerous, and Liu Bei had to find the weak point in their defense.

Then Liu Bei personally pressed toward the main Hanzhong battlefield.

Zhang He guarded Guangshi and came under heavy attack. He asked Xiahou Yuan for reinforcements. Xiahou Yuan divided his troops to help Zhang He while continuing to hold the southern line.

Fa Zheng saw the opening and advised Liu Bei to strike Xiahou Yuan.

Liu Bei ordered Huang Zhong to attack from high ground. Huang Zhong charged fiercely and killed Xiahou Yuan.

The Battle of Mount Dingjun became the turning point.

Later fiction, opera, and even early Chinese film made Huang Zhong's killing of Xiahou Yuan famous. In the historical sequence, the key was Fa Zheng recognizing the moment when Xiahou Yuan had divided his troops and exposed himself while repairing defenses.

Cao Cao Came in Person

Xiahou Yuan's death shook the Cao army.

For a moment there was no commander. The army eventually chose Zhang He to lead, and the line barely stabilized.

The next day, Liu Bei prepared to cross the Han River. Cao's generals wanted to deploy close to the water because they had fewer troops.

Guo Huai disagreed. Placing the army close to the river would look weak. Better to stand farther from the water and make Liu Bei think there was a chance. Then, when Liu Bei was half across, they could strike.

The Cao army followed this plan.

Liu Bei saw the formation away from the river and sensed a trap. He refused to cross. The armies faced each other along the Han, and Cao's side failed to lure him in.

Guo Huai had not fooled Liu Bei, but he helped stabilize the army after Xiahou Yuan's death.

Cao Cao heard the news and personally marched from Chang'an through Xie Valley to fight Liu Bei.

This was not the old Liu Bei running from place to place. He now held strong ground and refused battle. Cao Cao had marched far, and supply was difficult. For more than a month, he could not force Liu Bei to come out.

During this standoff, Huang Zhong went to seize Cao grain and failed to return on time. Zhao Yun worried and rode out with only several dozen cavalry to meet him. He ran into a large Cao force.

Zhao Yun fought while retreating. Back at camp, he opened the gates wide, lowered the banners, and silenced the drums. Cao's men suspected an ambush and did not attack. When they withdrew, Zhao Yun ordered drums beaten and crossbows fired. The Cao troops panicked, and many fell into the Han River.

The next day, Liu Bei came to Zhao Yun's camp, heard the story, and praised him as all courage.

Xiahou Yuan had died. Zhang He and Guo Huai had kept the line from immediate collapse. Zhao Yun had shaken Cao morale by the river. Even with Cao Cao personally present, the campaign would not open for him.

Hanzhong Went to Liu Bei

Cao Cao stayed in Hanzhong without result, and desertion increased.

In the fifth month of 219, he withdrew to Chang'an. Liu Bei took all of Hanzhong.

The central strategist for Liu Bei in this campaign was Fa Zheng. Zhuge Liang mainly stayed behind to secure supplies from Yi Province.

This differs from later storytelling, which often gives much of the battlefield planning to Zhuge Liang. In the Hanzhong campaign itself, Liu Bei leaned most heavily on Fa Zheng, who understood the Yi Province situation and saw the gap in Cao Cao's western deployment.

With Hanzhong in hand, Liu Bei finally secured Yi Province's northern gate.

Shu was no longer only newly seized territory. It had a forward barrier against Cao Cao.

The next episode follows the unresolved Jingzhou debt, where friendship between Shu and Wu begins to harden into conflict.