The Jin Dynasty’s Precarious Position

By the early 13th century, the Jin Dynasty (1115–1234) ruled northern China but faced existential threats from the rising Mongol Empire under Genghis Khan. The Jin had once been a formidable power, having overthrown the Liao Dynasty and pushed the Song Dynasty south. However, internal decay, military overextension, and the relentless Mongol campaigns weakened its foundations.

In 1214, the Jin capital, Zhongdu (modern Beijing), was already under severe pressure. Emperor Xuanzong, recognizing the vulnerability of the city, made a fateful decision: he would relocate the court south to Nanjing (modern Kaifeng), abandoning Zhongdu to its fate. This move, intended as a strategic retreat, instead signaled desperation—a moment that would accelerate the Jin’s downfall.

The Flight South and Mongol Retaliation

In July 1214, the Jin court completed its hurried migration to Nanjing, leaving Zhongdu exposed. Genghis Khan, interpreting the relocation as a betrayal of earlier peace negotiations, was furious. He saw it not as a retreat but as a deceptive maneuver, declaring: “They made peace and then fled—this shows their distrust and lingering resentment!”

Mongol forces, led by the general Samuqa Ba’atur and the defected Khitan commander Shimo Ming’an, swiftly advanced through the strategic Gubeikou Pass, a narrow mountain corridor described as “so tight that only a single cart could pass.” Once through, the flat plains of Hebei lay open before them. Mongol troops captured key cities—Jingzhou, Jizhou, Tanzhou, and Shunzhou—encircling Zhongdu.

The Betrayal of the Juyin Army

Compounding Zhongdu’s crisis was Emperor Xuanzong’s disastrous mistrust of the Juyin army, a multi-ethnic auxiliary force. Fearing rebellion, he ordered their weapons and horses confiscated during the southward march. The enraged Juyin troops mutinied, killing their Jin commanders and aligning with the Mongols. Now, Zhongdu faced a dual siege: Mongol forces from the north and the rebellious Juyin from within.

The poet Hao Jing later captured the despair in his “Ode to the Ten Loyalists of the Jin,” writing:

“A thousand Mongol riders encircle Yanjing (Zhongdu),
The emperor flees in haste from his throne.
A lone city, a pebble before the storm,
Fights desperately, drenched in blood.”

The Last Stand of Wanyan Chenghui

Left to defend Zhongdu was Wanyan Chenghui, a seasoned Jin official who had lost his family in earlier Mongol raids. Promoted to chancellor and military commander, he was effectively abandoned—his pleas for reinforcements met with hollow promises. Emperor Xuanzong, paralyzed by indecision, sent half-hearted relief efforts. A critical supply convoy led by Li Ying was ambushed and destroyed, sealing Zhongdu’s fate.

By spring 1215, starvation gripped the city. Desperate defenders melted down metal objects—even gold and silver—to make projectiles. Chenghui, realizing the end was near, sent a final plea via “alum letter” (invisible ink), warning that losing Zhongdu would mean losing all northern territories. The emperor’s reply was empty reassurance.

The Fall and Its Aftermath

On May 2, 1215, Chenghui confronted his deputy, Mo Nian Jinzhong, who had secretly planned to flee. After executing Jinzhong’s treacherous aide, Chenghui composed a final memorial condemning the corrupt chancellor Hushahu Gaogi, distributed his wealth to servants, and drank poison. His last words: “I have lived by the teachings of the sages—I die without regret.”

Jinzhong fled that night, callously abandoning imperial consorts at the city gates. Shortly after, Zhongdu surrendered. Though some records suggest a peaceful transition, others describe horrific scenes: palaces burned for weeks, streets littered with corpses, and mass suicides by women fearing Mongol enslavement.

Legacy: The End of an Era

The fall of Zhongdu marked the irreversible decline of the Jin Dynasty. By 1234, the Mongols would extinguish it entirely. Yet the siege’s drama—Chenghui’s loyalty, Jinzhong’s betrayal, and the civilian suffering—became a poignant symbol of dynastic collapse. For the Mongols, capturing Zhongdu was a stepping stone to conquering all China under Kublai Khan.

Centuries later, the siege remains a case study in leadership failure, military strategy, and the human cost of empire. As Hao Jing lamented: “A lone city, a pebble before the storm.” Zhongdu’s fall was not just the loss of a capital—it was the unraveling of a world.