The Conquest of Shu by Wei was a military campaign launched by the dynastic state of Cao Wei against its rival Shu Han in late 263 during the Three Kingdoms period of China. The campaign culminated in the fall of Shu Han and the tripartite equilibrium maintained in China for 43 years since the end of the Eastern Han dynasty in 220. The conquest laid the foundation for an eventual reunified China under the Western Jin dynasty in 280, 17 years after the fall of Shu.
Background
Following the end of the Eastern Han dynasty in 220, three contending states emerged in China and fought for control over the territories of the former Han Empire. Among the three, Wei was the most powerful one in terms of military prowess, economic resources, manpower and geographical size. The other two, Shu and Wu, re-established their alliance against Wei in 223.
Between 228 and 234, the Shu regent Zhuge Liang, who advocated an aggressive foreign policy towards Wei, launched a series of five military campaigns (known as the "Northern Expeditions") to attack Wei territories in Yong and Liang provinces (covering parts of present-day Gansu and Shaanxi). The ultimate goal of the campaigns was to clear the path for Shu forces to capture the Wei capital, Luoyang, and restore the Han dynasty. All the campaigns turned out unsuccessful. After Zhuge Liang died in 234, his successors Jiang Wan and Fei Yi adopted a more defensive stance against Wei and focused on policies promoting internal development and stability in Shu. However, between 240 and 262, the Shu general Jiang Wei followed up on Zhuge Liang's legacy by launching another 11 military campaigns against Wei. However, each campaign was ultimately aborted due to inadequate food supplies, heavy losses on the battlefield, or other reasons. The campaigns not only severely depleted Shu's already limited resources and took a heavy toll on Shu's population, but also resulted in much public resentment against Jiang Wei.
In the meantime, the Wei general Sima Yi came to power after staging a successful coup d'état in 249. After his death in 251, his eldest son Sima Shi succeeded him as regent and consolidated power and control over the Wei government. In 254, Sima Shi deposed the Wei emperor Cao Fang, who tried to seize back power from him, and installed Cao Mao on the throne. Following Sima Shi's death in 255, his younger brother Sima Zhao became the new regent and continued to monopolise power in Wei. In 260, Cao Mao attempted to launch a coup d'état to overthrow Sima Zhao but failed and lost his life. Cao Huan, who succeeded Cao Mao as the Wei emperor, remained a puppet ruler under Sima Zhao's influence and control.
Wei strategic planning
Wei decision to attack Shu
In 262, Sima Zhao noted that Shu was growing weak and lacking in resources after constantly waging war against Wei, so he wanted to launch a large-scale invasion of Shu to eliminate the threat of Shu. Among those he consulted, only Zhong Hui agreed that Wei was capable of conquering Shu. Zhong Hui then assisted Sima Zhao in formulating a strategy for the conquest of Shu.
Sima Zhao made an announcement to the Wei imperial court as follows:
"Since the Shouchun rebellions, we have not launched a military expedition for six years; we have trained our soldiers and repaired their armor, such that we may eliminate the two barbaric states. If we plan to conquer Wu, I estimate that the process of constructing ships and opening up waterways will take up more than 1,000 units of ten-thousand-manpower. In other words, we will need 100,000 labourers to work over a period of more than 100 days. Besides, the southern lands are humid, and our troops will surely fall victim to plague and disease. Therefore, I think we should conquer Shu first. Three years after that, we can make use of Shu's geographical advantage by sending our navy downstream along the river to attack Wu, while concurrently sending our army to invade Wu by land. It would be as easy as Jin conquering Yu and Guo, and Qin eliminating Han and Wei. According to our calculations, Shu has a 90,000-strong army, of which more than 40,000 troops guard Chengdu and the interior commanderies. This means they have fewer than 50,000 troops elsewhere. Presently, we can distract Jiang Wei at Tazhong and make him unable to deal with the situation to his east. We can then send our army through the Luo Valley where they are least defended, to seize control of Hanzhong. If the Shu forces remain in their forts and passes, they will be isolated from each other. We can send the bulk of our forces to conquer their cities and smaller detachments to seize their towns and villages. By then, they will have neither sufficient time nor manpower to guard Jiange and Yang'an Pass. At that point, with Liu Shan's ineptness as a ruler, with Shu's border defenses shattered, and with its people quivering with fear, the fall of Shu is inevitable."
The Wei general Deng Ai, who had been leading Wei forces to resist multiple Shu incursions along the Wei–Shu border since 255, voiced strong objections to the campaign against Shu. Sima Zhao worried that Deng Ai would embolden others to oppose the campaign as well, so he commissioned his registrar Shi Zuan (師纂) as a major under Deng Ai and ordered him to "persuade" Deng Ai. Deng Ai then changed his mind and supported the campaign.
Wei's three-pronged invasion of Shu
In the winter of 262, Sima Zhao appointed Zhong Hui as General Who Guards the West (鎮西將軍) and granted him imperial authority to oversee military affairs in the Guanzhong region. The Wei government also mobilised about 180,000 troops from the various provinces throughout Wei in preparation for the invasion of Shu. At the same time, the Wei government also put Tang Zi in charge of overseeing the construction of warships in preparation for a future invasion of Wei's other rival state, Wu.
In the autumn of 263, the Wei imperial court issued an edict outlining a three-pronged invasion of Shu:
- Deng Ai would lead 30,000 troops through Gansong (甘松; southeast of present-day Têwo County, Gansu) to attack Jiang Wei's position at Tazhong (沓中; northwest of present-day Zhugqu County, Gansu);
- Zhuge Xu would lead 30,000 troops to Wujie Bridge (武街橋; northwest of present-day Wen County, Gansu) to block Jiang Wei's retreat route;
- Zhong Hui would lead more than 100,000 troops to attack Shu via the Xie Valley (斜谷; southwest of present-day Mei County, Shaanxi);
- Zhong Hui's subordinates, Li Fu (李輔) and Hu Lie, would lead a detachment through the Luo Valley (駱谷; southwest of present-day Zhouzhi County, Shaanxi).
- The Wei imperial court authorised Wei Guan to supervise Zhong Hui and Deng Ai's military operations. Wei Guan also held the appointment of an acting military judge under Zhong Hui, and had command of 1,000 troops.
Shu strategic planning
Changes in the Shu defences at Hanzhong
Previously, when the Shu general Wei Yan first took charge of guarding Hanzhong Commandery in 219, he borrowed the concept of "double gates" from the Yijing and deployed heavily armed troops at interlocking camps on the outskirts and exits of trails leading into Hanzhong. These camps were meant to obstruct and hold off any invading forces. During the Battle of Xingshi in 244, the Shu general Wang Ping used the same strategy to defend Hanzhong from a Wei invasion led by Cao Shuang.
Jiang Wei pointed out that Wei Yan's idea of the interlocking camps was useful for only defence and would not provide additional advantages. He proposed vacating the camps and moving all their troops and resources to the two fortresses of Hancheng (漢城; east of present-day Mian County, Shaanxi) and Lecheng (樂城; east of present-day Chenggu County, Shaanxi), which provided access the Hanzhong Plain. The idea was to lure the invaders to attack the fortresses, overstretch their supply lines, and wear them down through guerrilla-style attacks. Once the invaders decided to retreat, the defenders would seize the opportunity to launch an all-out counterattack and defeat them.
In 258, Jiang Wei ordered Hu Ji, Jiang Bin and Wang Han (王含), who oversaw Hanzhong's defences, to dismantle the interlocking camps and move their troops and resources to Hanshou (漢壽; northeast of present-day Jiange County, Sichuan), Hancheng and Lecheng respectively. He also ordered the defence infrastructure to be strengthened at a number of locations around Hanzhong: Xi'an (西安), Jianwei (建威), Wuwei (武衛), Shimen (石門), Wucheng (武城), Jianchang (建昌) and Linyuan (臨遠).
Jiang Wei's early warning
In early 263, Jiang Wei wrote a memorial to the Shu emperor Liu Shan as follows:
"I heard that Zhong Hui has been mobilising troops in Guanzhong and appears to be preparing to launch an invasion. As a precautionary measure, I think we should send Zhang Yi and Liao Hua to lead our forces to guard Yang'an Pass and the bridge at Yinping."
One of Liu Shan's trusted eunuchs, Huang Hao, who believed in sorcery, believed a fortune-tellers' prediction that Wei would not invade Shu, so he advised the emperor to ignore Jiang Wei's memorial and not put it up for discussion in the imperial court.
Prelude
Between 20 September and 19 October 263, the Wei troops mobilised for the campaign had gathered in the Wei capital Luoyang and were ready to depart. Before they left, the Wei government gave out promotions and rewards, and staged a drill to boost their morale. During this time, when a Wei officer Deng Dun (鄧敦) said that Shu could not be conquered, Sima Zhao executed him as a warning to others to not speak ill of the campaign.
Zhong Hui had ordered Xu Yi, a son of the veteran Wei general Xu Chu, to oversee the construction of a road leading into Shu. However, when the road turned out to be poorly built, Zhong Hui disregarded Xu Yi's background and executed him for failing his mission. The Wei army was shocked at Zhong Hui's audacity.
Wei reinforcements
Between 20 October and 17 November 263, Sima Zhao ordered three commandery administrators to lead their garrison forces to join the campaign: Wang Qi (grandfather of Wang Mi) to lead troops from Tianshui Commandery to attack Jiang Wei's camp; Qian Hong to lead troops from Longxi Commandery and launch a frontal assault on Jiang Wei's position; and Yang Xin (楊欣) to lead troops from Jincheng Commandery (金城郡; around present-day Yuzhong County, Gansu) to attack Gansong.
Liu Qin (劉欽) also led troops from Weixing Commandery (魏興郡; around present-day Ankang, Shaanxi) to attack Hanzhong Commandery via the Ziwu Valley (子午谷; east of present-day Yang County, Shaanxi).
Shu response to the Wei invasion
Upon receiving news of the Wei invasion, the Shu government ordered Liao Hua to lead reinforcements to support Jiang Wei at Tazhong. At the same time, they also sent Zhang Yi, Dong Jue and others to lead troops to Yang'an Pass (陽安關; a.k.a. Yangping Pass 陽平關; in present-day Ningqiang County, Shaanxi) and assist the Shu forces defending the external perimeter.
When the Shu reinforcements reached Yinping (陰平; present-day Wen County, Gansu), they heard that the Wei army led by Zhuge Xu was attacking Jianwei (建威; northeast of present-day Wudu District, Longnan, Gansu), so they stopped in their tracks at Yinping.
Eastern flank
Lecheng and Hancheng
Around September or October 263, after his army passed through the Xie and Luo valleys as planned, Zhong Hui ordered his subordinates Li Fu and Xun Kai (荀愷) to each lead a detachment of 10,000 troops to attack Lecheng and Hancheng respectively. At the time, Lecheng and Hancheng were respectively guarded by the Shu officers Wang Han (王含) and Jiang Bin, who each commanded 5,000 troops.
During this time, Zhong Hui wrote to Jiang Bin to ask him for the location of the tomb of his father Jiang Wan. Jiang Bin politely obliged and told Zhong Hui that his father's tomb was in Fu County (涪縣; present-day Mianyang, Sichuan). Zhong Hui sent his men to pay respects on his behalf at Zhuge Liang's tomb at Mount Dingjun, and later visited Jiang Wan's tomb when he reached Fu County.
Wang Han and Jiang Bin managed to hold their positions at Lecheng and Hancheng respectively. After failing to capture either of the two fortresses, Zhong Hui led his army to bypass the two fortresses and move on towards Yang'an Pass. While Wang Han's eventual fate is unknown, it is recorded that after the fall of Shu, Jiang Bin surrendered to Zhong Hui at Fu County and befriended him.