Instead of being followed by mobs of refugees as was typical for the armies of the time, the Mongols were preceded by them, and the Mongols also used the displaced peasants in a more direct way as shields and as living battering rams against the city gates. The Mongols showed little concern for the loss of enemy life so long as it preserved Mongol life. As the captives fell in battle, their bodies helped to fill in the moats and form pathways over defensive holes and structures made by the enemies. Trapped inside their cities, the Jurched and their subjects starved; and in one city after another, they resorted to cannibalism. Discontent grew, and urban mutinies and peasant rebellions broke out against the Jurched officials, who proved unable to protect, feed, or manage the massive numbers of refugees. In the worst such rebellion, the Jurched army ended up killing some thirty thousand of their own peasants.
In contrast to the massive infantry armies that moved slowly and fought along a particular front or on a specific battlefield, the Mongols practiced warfare across the entire territory, and the ensuing turmoil and confusion allowed the Mongols to employ clever trickery of all sorts. In one episode, the Mongols captured a convoy with a high-ranking official en route to relieve the besieged city of Dading. One of the Mongols dressed in the envoy’s clothes, took his official papers, and proceeded to the enemy city in disguise. As he arrived, by prearrangement, the Mongol army lifted its siege and departed. Once inside the city, the Mongol pretender fooled the local officials into believing that they had just defeated the Mongols. The pretender then oversaw the painstaking dismantling of the city’s defenses and the withdrawal of troops. After several weeks of disarmament, he sent word to the Mongols, who returned like lightning and easily took the city.
The Mongols not only took advantage of such trickery, but in their relentless use of propaganda, they spread stories to foment anxiety and fear among the enemy. In one apocryphal account circulated to create anxiety among the enemy, the Mongols supposedly promised to retreat from a besieged city if the Jurched defenders would give them a large number of cats and birds as booty. According to the story, the starving residents eagerly gathered the animals and gave them to the Mongols. After receiving all the birds and animals, the Mongols attached burning torches and banners to their tails and released them, whereupon the frightened animals raced back into the city and set it on fire. The story supplied a dramatic dose of war propaganda.
After all the reconnaissance, organization, and propaganda, when the attack finally came, the Mongol army sought to create as much confusion and havoc for the enemy as possible. One of the most common forms of attack, similar to the Bush Formation, was the Crow Swarm or Falling Stars attack. At the signal of a drum, or by fire at night, the horsemen came galloping from all directions at once. In the words of a Chinese observer of the time, “they come as though the sky were falling, and they disappear like the flash of lightning.” The enemy was shaken and unnerved by the sudden assault and equally sudden disappearance, the roaring wave of noise followed by a greater silence. Before they could respond properly to the attack, the Mongols were gone and left the enemy bleeding and confused.
Beginning with the Tangut campaigns, Genghis Khan had discovered that Chinese engineers knew how to build siege machines that could batter city walls with massive stones from far away. The Chinese had already developed a number of those devices: the catapult hurled stones, flaming liquids, and other harmful substances at or across city walls; and the trebuchet, a catapult powered by the drop of a heavy counterweight, threw objects even faster than the torsion catapult. The ballista was a mechanical device that shot large arrows that could damage buildings and structures and kill any person or animal in its path. Although quite old in the military history of siege warfare, the weapons were new to the Mongols, but they soon became a permanent part of the arsenal of Genghis Khan, who appreciated the efficiency and ingenuity behind them. More than merely using the weapons, Genghis Khan acquired the engineering intelligence needed to create them. The Mongols eagerly rewarded engineers who defected to them and, after each battle, carefully selected engineers from among the captives and impressed them into Mongol service. Genghis Khan made engineering units a permanent part of the Mongol army, and with each new battle and each conquest, his war machinery grew in complexity and efficiency.
The siege engines exercised a particular fascination for the Mongols because they allowed the attackers to stay well outside of the city and away from the danger of the person-to-person combat that they so abhorred. At some point, the Mongols encountered the Jurched use of the firelance, a bamboo tube stuffed with gunpowder, which when lit produced a slow burn that spewed sparks, flames, and smoke out of the end of the tube like a flamethrower. Developed from firecrackers, this weapon was used to ignite fires and as a device to disorient the enemy and their horses; in later refinements, the Mongols would adapt it for many more military purposes.
When he could not overtake their fortifications, Genghis Khan tried to draw the enemy out from their stronghold through strategems such as pretending to retreat, as illustrated in Jebe’s siege of Liaoyang during the Jurched campaign. In a movement known as the Dog Fight tactic, he feigned a withdrawal, ordering his troops to leave behind a lot of their equipment and stores as though they had fled in great fearful haste. The city officials sent soldiers out to gather up the booty, and they quickly clogged the open gates with carts and animals transporting all the goods. With the soldiers on the open field, and the city gates opened, the Mongols fell upon them and raced through the open doors to capture the city.
As lifelong nomads, the Mongols learned early to fight on the move. For the soldier farmer, to flee meant to lose; to chase meant to win. The sedentary soldier sought to drive the attacker away from the place. The nomad sought to kill the enemy, and it mattered not at all whether he killed the enemy while attacking toward him or fleeing from him. For the Mongol, both directions represented fighting; a fleeing conquest was just as good as a stationary one. Once Mongols lured their opponents out of their walled cities, they applied the techniques they had learned for managing the movement of large groups of animals. Most commonly, they either strung their pursuers out in a long line that became increasingly defenseless and was easily attacked as soon as the Mongols had lured them into a trap, or the fleeing Mongols divided into their small squads and led their pursuers off in small groups that could be more easily overcome.
Even when routed or pursued by a determined enemy, the Mongols employed still more tricks with which to save themselves. If they were surprised and overtaken while on patrol, they usually carried some valuable items with them to strew on the ground as they escaped. The enemy invariably broke ranks to retrieve the goods, often fighting among themselves to do so, and thereby allowed the Mongols to escape. At other times, the Mongols threw sand in the wind or tied tree branches to their horses’ tails to whip up the dust in order to obscure their movements or to make the pursuers think that the Mongols were in much greater numbers than they actually were.
After the first year of the Jurched campaigns, it became clear that the worst danger for the Mongols derived not from battle but from the unpleasant climate. The lower altitude and closeness to great rivers and the ocean made the air hold its moisture, and in the summer, the heat and humidity became nearly unbearable for the Mongols and their shaggy horses. Repeatedly, they reported falling ill with a horrible variety of maladies when in the agricultural and urban areas. Campaigning nearly halted in the summer, when large numbers of the Mongols and their horse herds withdrew the relatively short distance to the higher and cooler grasslands of Inner Mongolia.