What is Guanzhong? How Difficult to Conquer it ？(Three Kingdoms 65)
The Battle of Guanzhong I
Previous Chapter ：The Southern Gambit: Wu's Conquest of Jiaozhou
From early 209 AD, after his defeat at Red Cliffs, until the end of 210 AD, Cao Cao retreated northward. For two full years, his once-unstoppable campaigns of conquest seemed to come to a halt.
During this time:
While Sun and Liu aggressively expanded their territories, Cao Cao adopted a defensive stance—even passive observation. Though he occasionally drilled his navy and inspected Hefei, his focus was primarily on recuperation:
Restoring weary morale.
Healing the wounds of defeat.
Dispelling the shadow of plague.
Reviving exhausted livelihoods.
Cao Cao understood that against the solid Sun-Liu alliance, he stood no chance of advancing south. Thus, he turned his gaze westward—to Liangzhou.
Liangzhou in Late Han period comprised two regions: Guanzhong关中 (within the passes) and Longxi 陇西(west of Mount Long陇山), separated by the Mount Long .
This vast, remote frontier, home to diverse ethnic groups, was fertile ground for warlords. Three centuries later, a powerful force would emerge here, blending cultures to forge another great empire.
The Guanzhong Plain, in particular, was a natural fortress—"within the passes"—guarded by four strategic strongholds:
Xiao Pass萧关 (North): Blocked Xiongnu and Xianbei cavalry from entering via the Jing River.
San Pass散关 (West): The throat of the Chencang陈仓 Path from Hanzhong汉中.
Han Xin’s legendary "repairing the plank roads while sneaking through Chencang" passed here.
Later, Cao Cao’s campaign against Zhang Lu张鲁 and Zhuge Liang’s second northern expedition both used this route.
The poet Lu You陆游 immortalized it: "Snow-clad ships at Guazhou by night, Iron steeds at San Pass in autumn wind."（楼船夜雪瓜洲渡，铁马秋风大散关）
Wu Pass武关 (South): The gateway from Nanyang南阳 Basin into Guanzhong.
Liu Bang刘邦（founder of Han,reigned 202-195BC） used it to overthrow Qin秦（770-207BC）.
Later rebels like Huang Chao黄巢 (Tang618-907AD) and Li Zicheng李自成 (Ming1366-1644AD) also marched through it.
Tong Pass潼关 (East): The most critical pass.
The Yellow River flows southward from Yumenkou禹门口, its channel suddenly widening into a majestic torrent.
However, upon reaching the vicinity of Fengling Ford风陵渡, it is blocked by the Qinling秦岭 Mountains to the south and Zhongtiao Mountain中条山 to the north, forcing it to turn eastward between the two mountain ranges.
Over centuries of erosion, both banks of the river have become riddled with crisscrossing gullies, rendering passage impossible for travelers.
Only along the southern bank lies a relatively flat, narrow corridor—the Xiaohan Ancient Road崤函古道—wide enough for carts and horses. This route, the shortest path connecting Chang’an (Xi’an) and Luoyang while linking the Central Plains to the Guanzhong Plain, has been a strategic military focal point since antiquity.
Hangu Pass函谷关, the eastern gateway of the Qin state during the Warring States period (475–221 BC), was strategically positioned along this treacherous Xiaohan Ancient Road.
Originally serving as the eastern guardian of Guanzhong ("Within the Passes"), Hangu Pass faced the Yellow River to its north—a stretch with steep elevation drops and rapids that made upstream navigation nearly impossible—and the towering Qinling Mountains to its south.
To enter Guanzhong from the Central Plains, armies had to traverse a 10-kilometer-long valley leading to the pass. The valley’s narrowest points were so cramped that two chariots could not pass each other, nor could several people walk abreast. The formidable Hangu Pass stood at the valley’s mouth.
Attacking the pass required first crossing the Hongnong River弘农河 under fire, while the limited space between the riverbank and the pass made it impossible to deploy large forces.
During the Warring States era, coalitions of six states repeatedly besieged Qin at Hangu Pass, only to retreat in despair. The Qin defenders, leveraging the Guanzhong Plain’s agricultural abundance (which produced over half of China’s grain at that time), easily outlasted their adversaries.
Later commentators even claimed that “a single bowl of mud blocking the valley mouth could have stopped the Central Plains’ armies from entering Guanzhong.”
When Liu Bang invaded Guanzhong to overthrow the Qin dynasty (207 BC), he avoided Hangu Pass entirely on Zhang Liang’s advice, detouring south through Wu Pass.
By the late Han period, however, falling Yellow River levels exposed vast stretches of its riverbed, allowing armies to bypass Hangu Pass via the dry banks.
Thus, the pass lost its strategic significance and was replaced by Tong Pass to its west.
Though similarly positioned along the Xiaohan Ancient Road, Tong Pass lacked Hangu Pass’s natural impregnability:
Armies could circumvent it by crossing the Yellow River at Fengling Ford, marching north, then re-crossing westward at Puban Ford蒲坂渡 to enter Guanzhong.
By the Tang dynasty, further riverbed exposure enabled forces to bypass Tong Pass entirely along the banks. Empress Wu Zetian武则天（the only female Emperor in China , reigned 690-705AD） abandoned the old pass and built a new one closer to the river, yet it remained vulnerable.
During the late Tang rebellion, Huang Chao’s forces found a hidden path to flank Tong Pass, breaching it through a pincer attack.
Once Tong Pass fell, the Guanzhong Plain lay defenseless, allowing the rebels to seize Chang’an and proclaim their leader emperor.
Thus, while Tong Pass remained formidable, it lost the “one man vs. ten thousand” advantage of Hangu Pass. Its defense now depended heavily on the skill of its garrison.
Since its construction in the late Han era, Tong Pass endured dozens of sieges, cementing its legendary status.
The Battle of Tong Pass in 211 AD—its first major conflict—catapulted the pass to fame.
Cao Cao’s victory over Ma Chao马超 and Han Sui韩遂 expelled these warlords from the region.
For Cao Cao, this triumph marked his transformation from a vassal of the Han dynasty to a de facto king, completing his ascent to unrivaled power!
To be Continued.
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