The Strategic Collapse of Shu Han

In the year 263 CE, during the Xingyuan era of Shu Han and Jingyuan era of Cao Wei, a pivotal military campaign unfolded that would dramatically alter the balance of power in the Three Kingdoms period. While Deng Ai advanced against Tazhong and Zhuge Xu attempted to intercept Jiang Wei on the roads, the main Wei forces under Zhong Hui launched a five-pronged invasion of Hanzhong.

Zhong Hui, hailing from an aristocratic family and a favorite of the Sima clan, had distinguished himself during the suppression of rebellions by Guanqiu Jian and Zhuge Dan. Unlike Deng Ai who opposed the invasion of Shu, Zhong Hui became its most vocal proponent. With most Wei officials opposing the campaign except for Sima Zhao and Zhong Hui, the latter gained his ruler’s complete trust and was appointed as the principal commander.

The invasion routes followed all major access points to Hanzhong:
– Chencang Road
– Baoye Road
– Tangluo Road
– Ziwu Road
– The Han River route from Nanyang through Ankang

This comprehensive approach would have been swiftly countered during Zhuge Liang’s era, when Shu’s defense strategy involved holding key passes and repelling invaders at the borders. However, post-Zhuge Liang, Shu’s defensive posture had significantly weakened, with troops concentrated in Han and Le cities while abandoning control of vital mountain passes. This allowed Wei forces to enter the Hanzhong basin virtually unopposed.

The Critical Defensive Points

Shu’s defensive strategy revolved around three key locations:
1. Han and Le cities in Hanzhong
2. Yang’an Pass at the entrance to Jinniu Road (the passage from Hanzhong to Sichuan)

The plan appeared sound in theory but required flawless execution. Yang’an Pass served as the linchpin – its fall would open the path to Sichuan regardless of other positions. Similarly, losing Han and Le cities would make Hanzhong unrecoverable, eventually dooming Yang’an Pass.

Tragically for Shu, their military discipline had deteriorated. When Zhong Hui’s forces reached Yang’an Pass, commander Jiang Shu surrendered without resistance, collapsing the entire defensive scheme within two days. With Yang’an Pass lost, Han and Le cities became isolated outposts, and Hanzhong’s fall became inevitable.

Jiang Wei’s Last Stand at Jianmen Pass

Following Yang’an Pass’s collapse, the strategic focus shifted to Jianmen Pass (modern Guangyuan, Sichuan), the final defensive line before the Sichuan basin. Shu reinforcements from Chengdu arrived too late and retreated to Jianmen, where Jiang Wei’s forces also withdrew after abandoning Qiaotou.

Jiang Wei’s strengthened defenses at Jianmen neutralized Wei’s initial advantages. Zhong Hui’s army began facing severe supply shortages, and the invasion appeared destined for limited success – holding Yang’an Pass and gradually taking Han and Le cities, but unable to advance further into Sichuan.

Deng Ai’s Audacious Gamble

History often turns on unexpected actors and events. Deng Ai, previously a peripheral figure in the campaign, suddenly altered the strategic balance through an unprecedented maneuver.

After failing to intercept Jiang Wei, Deng Ai discovered an alternative route through the Mian Mountains that bypassed Jianmen Pass entirely. Leading his troops through 700 li of treacherous, uninhabited terrain, they:
– Carved paths through mountains where none existed
– Built bridges across impassable gaps
– Descended steep slopes using blankets as makeshift sleds

Emerging suddenly at Jiangyou in the Sichuan basin, Deng Ai’s exhausted forces shocked the local defenders into immediate surrender. This foothold allowed him to advance toward Chengdu, defeating Zhuge Zhan (Zhuge Liang’s son) at Mianzhu after a desperate battle where Deng Ai reportedly threatened to execute his own son to maintain discipline.

The news of Zhuge Zhan’s death shattered Shu’s morale. Emperor Liu Shan, despite protests, surrendered Chengdu. Upon learning of this, Jiang Wei famously sighed to heaven before surrendering to Zhong Hui, marking the formal end of Shu Han in 263 CE.

The Evolving Strategic Geography of Sichuan

Shu’s collapse demonstrated Sichuan’s declining strategic importance. During the Warring States period, only two routes (Jinniu Road to Chengdu and Micang Road to Chongqing) connected Sichuan to central China, both requiring control of Hanzhong. By the Eastern Han, the Yangtze route from Hubei had emerged as another invasion path.

The Three Kingdoms period revealed even more access routes through Longyou, with Deng Ai’s campaign representing a pivotal moment in this geographical discovery. As more pathways were identified:
– Attacking Sichuan became a matter of choosing unexpected routes
– Defending Sichuan grew increasingly difficult
– The region lost its viability as a base for unifying China

However, Sichuan retained significance for northern regimes, providing an advantageous position to threaten the Middle Yangtze and Jiangdong regions. During north-south confrontations, southern control of Sichuan created balance, while its loss jeopardized defense of the entire Yangtze basin – a lesson soon demonstrated by Wu’s subsequent fall.

The Jin Conquest of Wu: A Masterclass in Coordinated Warfare

In 280 CE, the Western Jin launched one of history’s most impressive coordinated campaigns against Wu, spanning three thousand li and perfectly executing multi-front synchronization – a remarkable feat for pre-industrial warfare.

This operation represented the culmination of Three Kingdoms military evolution, applying lessons from decades of southern warfare to comprehensively exploit Wu’s geographical vulnerabilities. The conquest followed Jin’s usurpation of Wei in 265 CE and nearly two decades of preparation after suppressing the Tufa Shujineng rebellion.

### Strategic Planning and Challenges

Jin commanders like Yang Hu, Du Yu, and Wang Jun developed sophisticated plans addressing Cao Cao’s disastrous 208 CE defeat at Red Cliffs. They recognized that:
– Cao Cao’s single-axis attack amplified northern weaknesses in naval warfare
– Multiple coordinated fronts could leverage numerical superiority
– Southern geography required simultaneous pressure across regions

Five land routes and one naval route were identified for converging on Jianye (Nanjing):
1. Sima Zhou from Tuzhong threatening Jianye’s north
2. Wang Hun from Jiangxi (Anhui) toward Caishiji
3. Wang Rong from Wuchang
4. Hu Fen from Xiakou
5. Du Yu from Jiangling (Xiangyang to Jingzhou)
6. Wang Jun’s naval force from Ba-Shu down the Yangtze

### The Campaign Unfolds

Launched in November 279 CE, the six armies (totaling 200,000 troops) advanced with remarkable coordination under Grand Commander Jia Chong. Key moments included:
– Du Yu’s flexible command allowing Wang Jun to bypass rigid orders
– Zhang Ti’s doomed counterattack across the Yangtze against Wang Hun
– Wang Jun’s rapid naval descent covering 50 li daily
– The dramatic final approach where Wang Jun ignored Wang Hun’s order to halt, citing favorable winds

Wu’s Sun Hao, recognizing inevitable defeat, submitted surrender documents to both Wang Jun and Wang Hun simultaneously. Wang Jun’s fleet reached Jianye first, accepting the surrender on March 15, 280 CE.

Lasting Strategic Implications

The conquest revealed fundamental southern vulnerabilities:
1. Despite economic development, population and strategic depth remained insufficient against the north
2. Southern geographical units (Sichuan, Middle Yangtze, Gan River Valley, Jiangdong) proved too dispersed for effective coordination
3. Northern conquest required exploiting this dispersion through multi-front attacks

This template would dominate southern conquests for over a millennium, adapted by subsequent northern regimes including the Mongols. Conversely, southern defense strategies evolved around holding the Huai River line rather than the Yangtze – a lesson demonstrated by Eastern Jin’s victory at Fei River in 383 CE against Former Qin.

The fall of Shu and Wu marked not just the end of an era, but established enduring patterns in China’s military geography that would shape conflicts for centuries to come.