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 Timeline of the Conquest of Shu by WeiSanguozhi vols. 28, 33 and 44, Jin Shu vol. 2, and Zizhi Tongjian vol. 78. Approximate date range Location Event(s) Winter 262 Luoyang, Henan Sima Zhao announces his plan for the conquest of Shu to the Wei imperial court. He puts Zhong Hui in charge of military affairs in the Guanzhong region. Wei mobilises about 180,000 troops from its various provinces in preparation for the invasion of Shu. Early 263 Zhugqu County, Gansu Jiang Wei sends a warning to Chengdu that Wei appears to be preparing for an invasion of Shu. Huang Hao advises Liu Shan to ignore the warning. Autumn 263 Luoyang, Henan The Wei imperial court issues an edict outlining a three-pronged invasion of Shu: Zhong Hui, Deng Ai and Zhuge Xu would each lead an army to attack Shu from the eastern, western and central flanks respectively. 20 September – 19 October 263 Luoyang, Henan The Wei armies set out from Luoyang. Shaanxi Zhong Hui executes Xu Yi for failing his mission to oversee the construction of a road leading into Shu. Chenggu County and Mian County, Shaanxi Zhong Hui orders Li Fu and Xun Kai to attack Lecheng and Hancheng counties respectively. Wang Han and Jiang Bin manage to hold their positions at Lecheng and Hancheng respectively. Ningqiang County, Shaanxi Zhong Hui sends Hu Lie to attack Yang'an Pass. Jiang Shu surrenders to Hu Lie and assists him in conquering Yang'an Pass. Fu Qian is killed in action while defending the pass. 20 October – 17 November 263 Tianshui, Longxi County and Yuzhong County, Gansu, and Ankang, Shaanxi Wei Commandery administrators Wang Qi, Qian Hong, Yang Xin and Liu Qin lead troops from their respective commanderies to join the invasion of Shu. Longnan and Wen County, Gansu Liu Shan sends Liao Hua, and Zhang Yi and Dong Jue, to lead reinforcements to Tazhong and Yang'an Pass respectively. The Shu reinforcements stop at Yinping when they learn that Zhuge Xu's army is attacking Jianwei. Zhugqu County, Gansu Deng Ai defeats Jiang Wei at Tazhong. Intersection of the Bailong and Jialing rivers Jiang Wei attempts to retreat to Baishui but Yang Xin intercepts him at Qiangchuankou and defeats him. Wen County, Gansu Jiang Wei heads north to Konghan Valley to bypass Zhuge Xu, who is blocking Wujie Bridge near Yinping. When Zhuge Xu lifts the blockade, Jiang Wei quickly turns back, crosses the bridge and moves on to Jiange. Zhuge Xu arrives too late to stop Jiang Wei. Jiange County, Sichuan Jiang Wei, Liao Hua, Zhang Yi and Dong Jue retreat to Jiange. Zhong Hui attacks Jiange several times but fails to breach the Shu defences. Wen County, Gansu and Jiange County, Sichuan Deng Ai comes up with the idea of taking a shortcut from Yinping to Mianzhu to bypass Jiange's defences and go straight for Chengdu. He asks Zhuge Xu to join him but the latter refuses. Zhong Hui frames Zhuge Xu for cowardice and seizes command of his army. 18 November – 17 December 263 Wen County, Gansu Deng Ai leads an elite strike force through a shortcut bypassing Jiange and leading from Yinping to Chengdu. Jiangyou, Sichuan Ma Miao, the Shu administrator of Jiangyou, surrenders to Deng Ai. Mianzhu, Sichuan Deng Ai defeats Zhuge Zhan at Mianzhu. Zhuge Zhan, Zhuge Shang, Huang Chong, Li Qiu and Zhang Zun are killed in battle. Mianyang, Sichuan Jiang Wei abandons Jiange and heads towards Ba Commandery. Zhong Hui moves to Fu County and orders Hu Lie, Tian Xu and Pang Hui to pursue Jiang Wei. Chengdu and Guanghan, Sichuan Liu Shan sends Zhang Shao, Qiao Zhou and Deng Liang to bring his surrender document and imperial seal to Deng Ai at Luo County. He also instructs Zhang Jun and Jiang Xian to relay his orders for the rest of Shu to surrender to Wei. He sends Li Hu to order Jiang Wei to surrender to Zhong Hui at Fu County. Chengdu, Sichuan Deng Ai and his forces occupy Chengdu. Mianyang, Sichuan Jiang Wei surrenders to Zhong Hui at Fu County.
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.(文王以蜀大將姜維屢擾邊陲，料蜀國小民疲，資力單竭，欲大舉圖蜀。惟會亦以為蜀可取，豫共籌度地形，考論事勢。) Sanguozhi vol. 28.
Sima Zhao made an announcement to the Wei imperial court as follows:
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.(征西將軍鄧艾以為未有釁，屢陳異議。帝患之，使主簿師纂為艾司馬以喻之，艾乃奉命。) Jin Shu vol. 2.
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.(景元三年冬，以會為鎮西將軍、假節都督關中諸軍事。文王勑青、徐、兖、豫、荊、揚諸州，並使作船，又令唐咨作浮海大船，外為將伐吳者。) Sanguozhi vol. 28. The 10th to 12th months of that year correspond to 29 Nov 262 to 26 Jan 263 in the Julian calendar.(於是征四方之兵十八萬，使鄧艾自狄道攻姜維於遝中，雍州刺史諸葛緒自祁山軍於武街，絕維歸路，鎮西將軍鐘會帥前將軍李輔、征蜀護軍胡烈等自駱穀襲漢中。) Jin Shu vol. 2.
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).([景元]四年秋，乃下詔使鄧艾、諸葛緒各統諸軍三萬餘人，艾趣甘松、沓中連綴維，緒趣武街、橋頭絕維歸路。會統十餘萬衆，分從斜谷、駱谷入。) Sanguozhi vol. 28. 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.(鄧艾、鐘會之伐蜀也，瓘以本官持節監艾、會軍事，行鎮西軍司，給兵千人。) Jin Shu vol. 36.
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.(初，先主留魏延鎮漢中，皆實兵諸圍以禦外敵，敵若來攻，使不得入。) Sanguozhi vol. 44. 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.(及興勢之役，王平捍拒曹爽，皆承此制。) Sanguozhi vol. 44.
Jiang Wei pointed out that Wei Yan's idea of the interlocking camps was useful for only defence and would not provide additional advantages.(維建議，以為錯守諸圍，雖合周易「重門」之義，然適可禦敵，不獲大利。) Sanguozhi vol. 44. 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.(不若使聞敵至，諸圍皆歛兵聚穀，退就漢、樂二城，使敵不得入平，且重關鎮守以捍之。有事之日，令游軍並進以伺其虛。敵攻關不克，野無散穀，千里縣糧，自然疲乏。引退之日，然後諸城並出，與游軍并力搏之，此殄敵之術也。) Sanguozhi vol. 44.
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).(於是令督漢中胡濟却住漢壽，監軍王含守樂城，護軍蔣斌守漢城，又於西安、建威、武衞、石門、武城、建昌、臨遠皆立圍守。) Sanguozhi vol. 44.
Jiang Wei's early warning In early 263, Jiang Wei wrote a memorial to the Shu emperor Liu Shan as follows:
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.(皓徵信鬼巫，謂敵終不自致，啟後主寢其事，而羣臣不知。) Sanguozhi vol. 44.
Prelude