The Collapse of Tong Pass and Imperial Panic

When news of Tong Pass’s fall reached Chang’an on the same day, it triggered a chain reaction that would unravel the Tang Dynasty’s golden age. Within twenty-four hours, Chancellor Yang Guozhong proposed fleeing westward to Sichuan. By the third day, Emperor Xuanzong summoned his officials for counsel, only to find them paralyzed with fear, offering no solutions. The imperial court’s disintegration accelerated rapidly – by nightfall of the third day, officials began deserting in droves, leaving fewer than one in ten remaining for the fourth day’s court session. As dusk fell on that fourth catastrophic day, the emperor himself prepared for flight.

This frantic evacuation marked the beginning of the Tang Dynasty’s most humiliating chapter. On the fifth morning, Emperor Xuanzong fled with his royal family, concubines, and closest advisors, abandoning the glorious capital that had symbolized China’s cultural zenith. The imperial procession moved westward toward Mawei Slope, where history would deliver another brutal blow to the shattered dynasty.

The Mawei Slope Incident: Imperial Humiliation

At Mawei Slope, just west of Chang’an, the emperor’s own guards mutinied in one of Chinese history’s most dramatic political murders. The soldiers executed Chancellor Yang Guozhong, then forced the emperor to strangle his beloved Consort Yang Yuhuan – the legendary Yang Guifang whose beauty had inspired countless poems. This violent purge reflected the troops’ strategic concerns as much as their rage against corrupt leadership.

The military insisted the emperor avoid Sichuan, understanding its geographic trap. While offering temporary refuge, Sichuan’s mountainous isolation would permanently sever connections to northern China’s political heartland. Retreating there would reduce the mighty Tang Empire to a regional rump state, abandoning claims to imperial legitimacy. The soldiers’ intervention demonstrated how military leaders now dictated imperial policy amid collapsing central authority.

Strategic Crossroads: The Road Not Taken

Remarkably, all was not yet lost militarily when Xuanzong fled. Beyond Tong Pass, Tang forces still held most natural fortifications surrounding the Guanzhong Plain. In the north, Lingwu and Taiyuan remained formidable bases under commanders like Guo Ziyi, poised to strike rebel flanks. Lingwu particularly, as territory of the formidable Shuofang governor Guo Ziyi, represented the Tang’s most reliable stronghold.

The crown prince Li Heng recognized this strategic reality when he broke from his father’s retreat to Sichuan, instead heading north to Lingwu where he declared himself Emperor Suzong. This political-military schism created competing centers of Tang authority just as the rebellion reached its climax. Suzong’s faction understood that holding northern bases could preserve Tang military capacity, while Xuanzong’s Sichuan retreat signaled abandonment of northern territories.

The An Lushan Rebellion’s New Phase

Suzong’s accession opened the Tang’s most perilous chapter. Tong Pass’s fall had reversed what should have been a decisive victory over An Lushan’s rebels. Military stalwarts Guo Ziyi and Li Guangbi now withdrew from Hebei to Taiyuan and Shuofang, abandoning loyalists like Yan Zhenqing. With An Lushan occupying both Chang’an and Luoyang, the Tang controlled only fragmented territories while rebels dominated north China’s heartland.

The Tang’s remaining strongholds faced dire logistical challenges. Shuofang and Taiyuan in the northwest lacked agricultural capacity, requiring precarious grain shipments through rebel-held territory. While southern regions like Jiangnan and Sichuan had food surpluses, rebel destruction of canal networks severed supply routes to northern armies. This logistical nightmare birthed an ingenious but tortuous new supply line:

Grain from Jiangnan and Jianghan regions first concentrated at Xiangyang, then traveled the Han River to Hanzhong. From there, porters carried supplies north across the Qin Mountains, bypassing rebel-held Chang’an to reach Baoji, then onward to Guyuan and northern fronts. This 2,000-li detour, though inefficient, sustained Tang resistance forces.

The Li Bi Strategy: A Lost Opportunity

Amid this crisis, a remarkable strategist named Li Bi emerged in Suzong’s court. Refusing official titles, this brilliant recluse proposed an unconventional plan to crush the rebellion without directly assaulting the rebel-held capitals:

1. Have Li Guangbi harass rebel bases in Hebei from Taiyuan
2. Order Guo Ziyi to threaten Hedong from Fengyi, creating a northern pincer
3. Dispatch Prince Li Tan on an audacious flanking maneuver through Inner Mongolia to attack the rebel base at Youzhou (Beijing)

This brilliant three-pronged strategy aimed to exhaust rebel forces through constant harassment while preparing a decisive strike at their headquarters. Li Bi argued that directly recapturing Chang’an and Luoyang would merely scatter rebels to regroup, while destroying their power base could end the rebellion permanently.

Had Suzong fully implemented Li Bi’s plan, the Tang might have avoided the subsequent century of warlord dominance. Instead, the emperor opted for conventional attacks on the capitals with Uighur assistance. While this temporarily recaptured Chang’an and Luoyang, it allowed rebel remnants under Shi Siming to continue resistance from Hebei – prolonging the conflict for years and fatally weakening central authority.

The Birth of Regional Warlordism

The rebellion’s chaotic conclusion planted seeds for Tang decline. To quickly end hostilities, general Pugu Huai’en allowed rebel commanders like Tian Chengsi and Li Baochen to retain military governorships (jiedushi) over Hebei provinces. These former rebels became autonomous warlords, establishing hereditary control that the weakened court couldn’t challenge.

By rebellion’s end, thirty-six military governors divided Tang territory, controlling local armies, taxes, and administration. The central government’s authority eroded as these regional strongmen operated independently. Some even openly defied imperial orders, establishing dynastic succession within their fiefdoms. The Tang Empire had survived, but as a hollow shell of its former centralized glory.

The Long Shadow of An Lushan

The An Lushan Rebellion’s aftermath fundamentally reshaped Chinese governance. Military governors became permanent features of Tang politics, their regional power bases challenging central authority for over a century. The court’s desperate measures during crisis – creating new governorships, granting autonomy to secure loyalty – became institutionalized weaknesses.

This new balance of power created a paradoxical stability. No single warlord could dominate the system, yet all resisted centralization. The Tang court persisted as nominal sovereign while real power diffused among regional commanders. This uneasy equilibrium lasted until the dynasty’s final collapse in 907, demonstrating how emergency measures taken during the flight from Tong Pass reshaped Chinese governance for generations.

The rebellion’s legacy extended beyond politics. Culturally, it marked the end of the Tang’s cosmopolitan golden age. The trauma of imperial flight, massacres, and economic collapse produced more introspective literature and arts. Socially, aristocratic dominance waned as military men rose to power. Economically, the prosperous north never fully recovered, accelerating China’s gradual southward shift in demographic and economic gravity.

Ultimately, those five desperate days following Tong Pass’s fall marked more than a military defeat – they represented the unraveling of an era and the painful birth of a new political order whose consequences would echo through Chinese history for centuries.