The Prelude to Invasion: Wei’s Multi-Pronged Offensive

In the autumn of 263 AD, the fate of the Shu Han kingdom hung in the balance as the rival state of Cao Wei launched a meticulously coordinated invasion. Under the command of Zhong Hui, over 100,000 Wei troops advanced through the Xie Valley and Luo Valley towards Hanzhong, the northern stronghold of Shu. Meanwhile, Deng Ai, the General Who Conquers the West, led 30,000 soldiers from Di Province to harass Jiang Wei, Shu’s most capable general, in the Tazhong region. To complete the encirclement, Zhuge Xu, Inspector of Yong Province, marched 30,000 troops from Qishan to cut off Jiang Wei’s retreat at Yinping Bridge, while Liu Qin, Governor of Weixing, brought 20,000 reinforcements via the Ziwu Route.

This was no ordinary campaign—Wei had committed forces to every major approach except Chencang Pass, demonstrating their determination to crush Shu once and for all. The strategic situation was dire for Shu, yet Jiang Wei, the architect of Shu’s northern defenses, remained inexplicably inactive in Tazhong as the crisis unfolded.

The Collapse of Hanzhong: A Chain of Strategic Failures

Shu’s emperor Liu Shan, recognizing the gravity of the situation, finally dispatched reinforcements—Liao Hua to rescue Jiang Wei in Tazhong, and Zhang Yi and Dong Jue to defend Yang’an Pass. But it was too little, too late.

Hanzhong’s 10,000 defenders, following Jiang Wei’s controversial “lure and ambush” strategy, abandoned their perimeter defenses and retreated to the fortified cities of Han and Le. Zhong Hui, displaying brilliant tactical flexibility, bypassed these strongholds entirely. He assigned 10,000 troops each to besiege Han and Le cities while personally leading the main force toward Yang’an Pass—the true key to Hanzhong.

The defense of Yang’an Pass, a natural fortress that had withstood both Cao Cao and Liu Bei in previous campaigns, collapsed due to internal betrayal. Deputy commander Jiang Shu, resentful after being demoted, tricked his superior Fu Qian into allowing a sortie, then promptly defected to Wei forces. The pass fell, marking the beginning of the end for Shu’s northern defenses.

Jiang Wei’s Strategic Blunders: A General’s Fatal Indecision

While Hanzhong crumbled, Jiang Wei faced his own crisis in Tazhong. Deng Ai had coordinated a three-pronged attack against him, yet Jiang Wei delayed his retreat until Yang’an Pass had already fallen. When he finally moved, Deng Ai’s forces pursued relentlessly, defeating him at Qiangchuankou.

Jiang Wei’s subsequent attempt to outmaneuver Zhuge Xu at Yinping Bridge—feigning a retreat only to double back—was tactically brilliant but strategically insignificant. More critically, upon learning of Yang’an Pass’s fall, Jiang Wei made perhaps his gravest error: abandoning the vital Bai Shui Pass, the gateway controlling all conventional routes into Sichuan.

This decision would have catastrophic consequences. As historian Rafe de Crespigny notes, “The loss of Bai Shui Pass removed the last geographical barrier that might have prevented Deng Ai’s later dramatic march through Yinping.”

Deng Ai’s Daring Gamble: The Impossible March

With Zhong Hui’s 150,000 troops bogged down at Jian’ge Pass, Deng Ai proposed an audacious plan: to bypass the impenetrable Jian’ge defenses by traversing the treacherous Yinping Trail—a 700-li (approximately 350 km) path through uninhabited mountains where soldiers would need to roll down slopes wrapped in felt blankets.

Zhuge Xu refused to participate, considering the march suicidal. But Deng Ai, motivated by personal ambition and recognizing that Shu’s collapse would cement Sima Zhao’s power (and his own position), took the gamble. His forces suffered horrific casualties—nearly half perished during the march—but emerged unexpectedly at Jiangyou in November 263.

The psychological impact was devastating. As the Zizhi Tongjian records, “When Deng Ai’s tattered forces appeared at Jiangyou, the defenders surrendered without resistance.” The rapid collapse that followed—including the defeat of Zhuge Zhan (Zhuge Liang’s son) at Mianzhu—demonstrated how thoroughly Shu’s will to resist had eroded.

The Final Collapse: Systemic Failure of the Shu State

As Deng Ai approached Chengdu, Shu’s court debated surrender. The scholar Qiao Zhou famously argued for capitulation, claiming resistance was futile—a stark contrast to Liu Zhang’s defenders who had resisted Liu Bei for over a year at Luocheng in 214.

The rapid collapse revealed deeper issues:
1. Strategic Overreach: Jiang Wei’s aggressive northern campaigns had exhausted Shu’s resources without securing lasting advantages.
2. Defensive Complacency: The “lure and ambush” strategy assumed perfect execution that never materialized.
3. Moral Collapse: Decades of Chou Guo Lun (“Discourse on Rival States”) rhetoric had undermined belief in Shu’s legitimacy.

When Liu Shan surrendered on Qiao Zhou’s advice, it merely formalized what had already occurred militarily and psychologically. The once-proud state founded by Liu Bei and nurtured by Zhuge Liang ended not with a bang, but a whimper.

Legacy and Historical Assessment

The fall of Shu offers enduring lessons about strategy and statecraft:
– Geography’s Limits: Even the most formidable natural defenses are useless without competent defenders.
– Strategic Patience: As the Art of War emphasizes, victories are built through preparation, not gambling.
– Moral Authority: A state’s survival depends not just on arms, but on its subjects’ belief in its legitimacy.

Jiang Wei’s seven critical failures—from his initial strategic dispersal to his final abandonment of Jian’ge—illustrate how individual decisions can accelerate systemic collapse. Yet the deeper tragedy lies in how thoroughly Shu Han, the last bastion of the Han ideal, had internally surrendered before the first Wei soldier reached Chengdu’s gates.

As the Records of the Three Kingdoms poignantly notes, “The mountains and rivers remained, but the spirit of resistance had fled.” The conquest of Shu stands as history’s most dramatic demonstration that even the most defensible terrain cannot compensate for lost purpose and fractured will.