Geography of War - The Battle of Yehuling
The Battle of Yehuling (Mongol-Jin War)
Northern China (NW of Beijing)
The Mongol Empire (led by Genghis Khan) vs. Jin China (led by Wanyan Chengyu)
In the year 1211, Genghis Khan was on a mission. After emerging victorious five years earlier from a bitter struggle to assume leadership of the Mongol confederation to the north and then defeating the rival Tatars to the east, he set his sights south towards the Chinese Jin empire. Although the majority of the Jin population were ethnically from the Han and Khitan people groups, the emperor and leadership came from the Jurchen people group, originally from Manchuria. Khan was unimpressed by the new Jin emperor who had ascended in 1208, named Xingshing, and publicly insulted him as an ineffective and cowardly ruler. Emperor Xingshing, on the other hand, focused his defenses against the southern Song dynasty did not consider the Mongols to be a legitimate threat even after Khan's armies had defeated both the Onggud tribe of Mongols and the Xi Xia dynasty, both of which were vassal groups to the Jin leadership and served as a buffer against invasion. A line of fortifications existed through the mountainous terrain, which would eventually be linked together to form the Great Wall, but it was an ineffective defense against the mounted armies that the Mongols used for their invasion.
The Jin greatly outnumbered the Mongol invaders and had the advantage of fighting a defensive war with fortified structures. But Genghis Khan used mobility, deceptive tactics, and the disloyalty of marginalized groups within the Jin empire to his advantage. Riding around the western extents of the Jin defensive wall in the spring of 1211, he took advantage of the mistake by Jin chancellor Duji Sizhong to attempt to spread his defenses along the wall instead of concentrating them into a unified force. Khan wiped out the chancellor's forces, killing him in the process, at Wusha Fortress and after resting his troops continued ahead to Yehuling, which translated to English means "Wild Fox Ridge", where the bulk of Jin forces were blocking the path through the mountains that guarded the capitol city of Zhongdu (on the site of modern Beijing). Stopping in the plain for several months in an effort to lure the defenders out into an open fight, Khan instead received help in the form of a defection. An official named Shimo Ming'an was sent to the Mongol army to negotiate, but instead he surrendered and submitted to Genghis Khan and gave him intelligence on the strength, placement, and makeup of Jin forces around the mountain pass. After a riveting speech to his men, the attack began at a point called Huan'erzui ("Badger Mouth") with a barrage of arrows into the Jin armies that were largely unprofessional and did not have strong loyalty to their emperor. Without effective communication to other segments of fighters throughout the nearby passes, there was no way to bring in sufficient reinforcements to counter the concentrated Mongol thrust. The cavalry charge which followed under the leadership of Khan's trusted commander, Muqali, caused a break in the defending lines within the mountain pass and started a disorganized rout. It was said that the extent of the massacre left corpses strewn for nearly 100 miles, and the bones were still piled high over 10 years later.
Scene of the battle from the perspective of the Mongol army approaching the mountain pass:
The mountains were the obvious barrier that Genghis Khan had to overcome to defeat the Jin armies, but ironically they also served to weaken the defensive efforts of the larger fighting force. The narrow passes limited the advantage of the renowned horsemanship of the Mongol cavalry, forcing them to dismount and fight on foot, but it also blunted the numerical advantage of the Jin. Additionally, it limited communication between smaller groups which allowed the attackers to sustain a concentrated attack for longer periods without worrying about reinforcements or flanking maneuvers. A secondary geographic factor in the Mongol invasion was the Gobi Desert that existed just north of the Jin dynasty's border. The large, arid region that provided a natural boundary between the two empires had to be crossed not just by Genghis Khan's men, but by their many horses as well. With a fighting force of over 100,000 men leaving Mongol lands with just 2,000 left behind, Khan had essentially bet the future existence of his people on their ability to conquer northern China.
The complete victory by Genghis Khan left the Jin capitol city exposed, but it was well-fortified and resisted the siege efforts by the Mongol army for a significant time. Khan eventually negotiated a peace with the Jin and exacted tribute, but not until after the emperor was assassinated by one of his generals and replaced. In an interesting twist, Xingshing was posthumously stripped of his title as emperor by his successor and is now instead remembered by history as Wanyan Yongji (Prince Shao of Wei). After his victory over the Jin dynasty, which was later entirely destroyed in 1234 by a coalition of Mongol and Song dynasty forces, Genghis Khan was able to continue the expansion of his empire which would eventually be the second largest to exist in recorded human history.