battle and be re-promoted. However, sending Generals of Front (前將軍, namely Li Guang) and Right (右將軍, namely Zhao Yiji) on flanking maneuvers was one of Wei Qing's typical tactical arrangements. This was evidenced by his previous deployment of Zhao Xin and Su Jian, who were Generals of Front and Right respectively, during the less successful 123 BC campaign. After crossing the desert, Wei Qing's army unexpectedly encountered Chanyu Yizhixie's main forces, who was waiting in anticipation of ambushing the Han army. Despite being significantly outnumbered as well as fatigued after the long journey, Wei Qing was able to counter Xiongnu's cavalry charge with archery defense created by heavy-armored chariots arranged in ring formations, which was reinforced with cavalry counteroffensives. (This defense would be evaluated as one of the most effective against cavalry by many later Chinese tacticians, including Yue Fei.) The Han forces successfully enforced a stalemate that lasted until dusk, when a sandstorm descended upon the battlefield. Seizing the moment of poor visibility provided by the dust, Wei Qing broke the stalemate and launched bilateral flanking attacks with his cavalries. Already exhausted after a day of unsuccessful attacks against Han positions, the sudden sight of incoming Han soldiers in the darkness further broke the Xiongnu's morale, routing them. This decisive pincer attack shattered the Chanyu's line, nearly capturing him and completely overrunning his forces, killing over 10,000 Xiongnu soldiers in the process. The Han army pursued all the way to the modern Ulan Bator region, destroying the Xiongnu stronghold Zhao Xin Castle (趙信城) before returning in triumph with a total of about 19,000 enemy kills. Chanyu Yizhixie was forced to escape with very few men, lost communication with his tribe for days, and did not return until his clan presumed his death and installed a new Chanyu. This was a narrow but critically significant victory for the Han empire. Xiongnu was greatly weakened to the point that they would huddle up into the barren northern Gobi desert (leading to decline of their population), and unable to raid south for the next decade. The next major Xiongnu invasion did not occur until after the Han dynasty collapsed, some 400 years later during the Jin Dynasty. Li Gan incident While Wei Qing's main force was engaging Yizhixie Chanyu, the flanking division led by Li Guang and Zhao Yiji got lost in the desert and failed to reach the battlefield in time,