The Battle of Mobei (漠北之戰, "Battle of the Desert's North") was a military campaign fought at the northern part of the Gobi Desert. It was part of a major strategic offensive launched by the Han Dynasty on January, 119 BC, into the heartland of the nomadic Xiongnu. The battle was a success for the Han, whose forces were led by Wei Qing and Huo Qubing.
Military tension between ancient China and the northern "barbarians" had been long-lasting, mainly because the fertile lands of the prosperous agricultural civilization presented an attractive targets for the militaristic nomadic tribes. Throughout ancient Chinese history, protecting northern borders from nomadic raids had been a military priority. During Zhou Dynasty, the northern vassal states such as Yan, Zhao and Qin resorted to defensive strategies, constructing elongated fortresses that served as the precursors of the famous Great Wall. During the Qin Dynasty, the First Emperor mobilized thousands of civilian labourers to perfect the Great Wall in order to reinforce military campaigns in the northern border.
Han Dynasty China and the nomadic Xiongnu Empire had had a very bitter relationship. Xiongnu was initially a group of small tribes suppressed by Qin Empire's military offensives under General Meng Tian. With the collapse of the Qin Dynasty and the subsequent Chinese civil war, Xiongnu gained the opportunity to become unified under Modu Shanyu, quickly expanded to a powerful tribal confederacy, invaded and occupied the fertile Hetao grassland (河套). When the Chu-Han contention concluded, Emperor Gao recognized the threat posed by the hostile northern neighbour, and launched a massive campaign in 200 BC. The Han army was lured into an ambush and encircled by 300,000 elite Xiongnu cavalry for seven days, and the siege was relieved only after messengers were sent to bribe the Shanyu's wife. After the failure, the Han empiror realized that the nation, just recovered from a massive civil war, was not strong enough yet to confront the Xiongnu, therefore resorting to the so-called "marriage alliance", or heqin, in order to ease hostility and buy time for the nation's strengthening. Despite the humiliating periodic heqin and gifting, the Han borders were still frequently raided by Xiongnu forces for the next seven decades.
During the reign of the ambitious Emperor Wu, he decided that the nation was finally strong enough to solve the Xiongnu problem once and for all. The "peaceful" atmosphere was broken in 133 BC, after a large ambush operation was staged at Mayi but aborted after the Xiongnu discovered the trap and retreated. In 129 BC, the Han forces had their first proper victory against the Xiongnu under the command of a young Wei Qing with a long-distance raid on the Xiongnu holy site of Longcheng (蘢城). In the next 10 years, Emperor Wu repeatedly deployed Wei and his vigorous nephew Huo Qubing against Xiongnu forces, recapturing large area of land and dealing devastating blows.
Evicted by the defeats, Yizhixie Chanyu (伊稚邪) took Zhao Xin's advices, and the Xiongnu tribes retreat to the north of the Gobi Desert, hoping that the barren land would serve as the natural barrier against Han offensives. In 119 BC, Emperor Wu planned a massive expeditionary campaign. Chinese forces were deployed in two columns, each consisting 50,000 cavalry and over 100,000 infantry. Wei Qing and Huo Qubing served as the supreme commanders, and set off from Dai Prefecture (代郡) and Dingxiang (定襄).
Initially it was planned to have Huo Qubing attacking from Dingxiang, however information from a Xiongnu prisoner of war suggested that the Chanyu's main forces was deployed to the east at Dai Prefecture (that information was actually false). Emperor Wu, who had been distancing Wei Qing and giving the younger Huo more attention and favour, ordered the two columns to switch routes in the hope of letting Huo (who was preferentially assigned the most elite troopers) engaging the Chanyu
The Eastern (Dai Prefecture) Theatre
The eastern theatre was quite straight forward, as the Han forces deployed was far more superior than the opposing Xiongnu forces.
Huo Qubing's forces set off from Dai Prefecture, marched over 1,000 miles and directly engaged the forces of Xiongnu's Worthy Prince of the East (左賢王, "Wise King of the Left"). The battle was swift and decisive, as the Worthy Prince's forces were no match for Huo's elite cavalry. The Huo's army quickly encircled and overran their enemy, killing 70,443 men and capturing 3 Xiongnu lords and 83 nobles. Huo Qubing's forces suffered a 20% casualty, but were quickly resupplied locally from their capture. He then went on to conduct a series of rituals upon arrival at Khentii Mountains (狼居胥山, and the more northern 姑衍山) in order to symbolize the historic Han victory, then continue pursue to as far as the Lake Baikal (瀚海), effectively annihilating the Xiongnu clan.
A separate division led by Lu Bode (路博德), set off for a strategically flanking route from Right Beiping (右北平), joined forces with Huo after arriving in time with 2,800 enemy kills. The combined forces then returned in triumph.
The Western (Dingxiang) Theatre
The western theatre, although not regarded with as much expectation from Emperor Wu, was by far more dramatic. Wei Qing's forces, setting off from Dingxiang, is comparatively weaker than its eastern counterpart, as it consisted mainly leftovers from Huo Qubing's preferential picks. Wei Qing also had other liabilities — he had five generals under his wing that needed assigning, including an old but enthusiastic Li Guang. Li Guang insisted that he wanted a vanguard position as promised by Emperor Wu, who also secretly messaged Wei not to do so as Li was well known to be jinxed with "bad fortune". Wei Qing then assigned Li Guang to combine forces with Zhao Shiqi (趙食其) on a barren eastern flanking route, an arrangement that Li protested and angrily stormed out of the main camp.
The Han army mobilized as planned, and after over 500 miles over journey, they encountered a 80,000-strong cavalry — the Chanyu's main forces. This was quite unexpected, as the original strategy was to let Huo Qubing's more elite troops deal with Chanyu's elite cavalry (the very reason that the two Han columns switched route). The Xiongnu forces, however, had been long waiting in anticipation to ambush their adversary. The Han forces, on the other hand, were tired and outnumbered, especially since the eastern division had not yet arrived in the battlefield. Without hesitation, the Xiongnu charged the Han forces with a 10,000-strong vanguard cavalry.
Wei Qing recognized the odds against him and quickly made defensive countermeasures. He ordered his troops to arrange heavy-armoured chariots (武剛車) in ring formations, creating mobile fortresses that provided archers, crossbowmen and infantry protection from Xiongnu's powerful cavalry charges, and allowing Han troops to utilize their ranged weapons' advantages in precision. A 5,000-strong cavalry was deployed to reinforce the array and eradicate any Xiongnu forces that managed to infiltrate in among the chariot rings. This tactic was proven extremely effective in countering the momentum of the nomadic cavalry, as the Xiongnu forces were unable to breach the Han army's lines. With the Xiongnu's initial energy neutralized, the battle solidified into a stalemate with neither side making significant gains or losses.
The stalemate lasted until dusk, when a sandstorm clouded the battlefield. Knowing that this was the chance, Wei Qing sent in his main forces. The Han cavalry used the low visibility as cover and encircled the Chanyu's army from both flanks. The Xiongnu's lines were overwhelmed, and their morale broken by the sight of Han soldiers attacking them amongst the dark wind. Seeing that his forces were overrun completely, the Chanyu escaped under the escort of only a few hundred men. The Han forces killed over 19,000 enemies, pursued another 100 miles to the Khangai Mountains, besieged and captured the Fortress of Zhao Xin, located in the Orkhon Valley. After they regrouped and resupplied there for one day, the Han forces burned the stronghold permanently to the ground, before returning in triumph.
The eastern division, commanded by Li Guang and Zhao Shiqi, got lost in the desert and missed the battle entirely, and only rejoined the main forces on Wei Qing's way home. As a result, Li and Zhao was summoned to court martial for failing to accomplish orders and putting the battle strategy at risk. Li Guang, frustrated and humiliated (that was his last chance to obtain enough battle distinction for a marquessate promotion), committed suicide to conserve his honour.
The battle in the western theatre was more strategically decisive. Chanyu's main forces was defeated so badly that they were unable to recover. The Chanyu went missing for over 10 days, resulting in that his tribe presumed his death and installed a new leader, who had to be removed after the Chanyu finally reappeared. The Xiongnu was forced to retreat further north, and their threat to the Han Dynasty's northern border had been largely obliterated.
The costs of the victorious campaigns over ten years over the Xiongnu from 129 to 119 BC were enormous: the Han army lost almost 80% of their horses to the expedition, due to combats as well as non-combative losses such as the harsh journey and plague by the Xiongnu contamination of water supply with dead cattle.
Economic pressure on the central Han government led to new taxes being introduced, increasing the burden on average peasants. The population of the Han Empire dropped significantly as a result of famine and excessive taxing to fund military mobilisations.
The Xiongnu, however, suffered a far more lethal blow, as their military losses would reflect directly onto their economy. Apart from loss of manpower due to wartime casualties and diseases, the nomadic Xiongnu lost millions of livestock (their vital food resource) to the Han army, and the war left large proportion of the remaining cattle suffering miscarriages during reproductive seasons.
Furthermore, the loss of control over the fertile southern grassland meant that Xiongnu had to hole up in the cold, barren land of northern Gobi Desert and Siberia, struggling to survive. As a result, there was a true ceasefire between the Han Dynasty and Xiongnu for seven years, which ended after a Xiongnu raid in 112 BC at Wuyuan. The Xiongnu, however, never recovered to the strength of their past glory days, and would break apart into smaller clans in the coming decades