Military of the Mongol Empire



During the Mongol invasions and conquests, which began under Genghis Khan in 1206–1207, the Mongol army conquered nearly all of continental Asia, including parts of the Middle East, and parts of Eastern Europe. The efforts of Mongol troops and their allies enabled the Mongol Empire to become the contemporarily largest polity in human history. Today, the former Mongol Empire remains the world's largest polity to have ever existed in terms of contiguous land area and the second-largest polity overall, behind only the British Empire.

Cavalry


Each Mongol soldier typically maintained 3 or 4 horses. Changing horses often allowed them to travel at high speed for days without stopping or wearing out the animals. When one horse became tired, the rider would dismount and rotate to another. The Mongols protected their horses in the same way as did they themselves, covering them with lamellar armor. Horse armor was divided into five parts and designed to protect every part of the horse, including the forehead, which had a specially crafted plate which was tied on each side of the neck.

Armor
Lamellar armor was worn over thick coats. The armor was composed of small scales of iron, chain mail, or hard leather sewn together with leather tongs and could weigh 10 kg if made of leather alone and more if the cuirass was made of metal scales. The leather was first softened by boiling and then coated in a crude lacquer made from pitch, which rendered it waterproof. Sometimes the soldier's heavy coat was simply reinforced with metal plates.

Helmets were cone shaped and composed of iron or steel plates of different sizes and included iron-plated neck guards. The Mongol cap was conical in shape and made of quilted material with a large turned-up brim, reversible in winter, and earmuffs. Whether a soldier's helmet was leather or metal depended on his rank and wealth.

Weapons


Mounted archers were a major part of the armies of the Mongol Empire, for instance at the 13th-century Battle of Liegnitz, where an army including 20,000 horse archers defeated a force of 30,000 troops led by Henry II, Duke of Silesia, via demoralization and continued harassment.

Mongol bow
The primary weapon of the Mongol forces was their composite bows made from laminated horn, wood, and sinew. The layer of horn is on the inner face as it resists compression, while the layer of sinew is on the outer face as it resists tension. Such bows, with minor variations, had been the main weapon of steppe herdsmen and steppe warriors for over two millennia; Mongols (and many of their subject peoples) were skillful archers. Composite construction allows a powerful and relatively efficient bow to be made small enough that it can be used easily from horseback.

Quivers containing 60 arrows were strapped to the backs of their cavalrymen and to their horses. Mongol archers typically carried 2 to 3 bows (one heavier and intended for dismounted use, the other lighter and used from horseback) that were accompanied by multiple quivers and files for sharpening their arrowheads. These arrowheads were hardened by plunging them in brine after first heating them red hot.

The Mongols could shoot an arrow over 200 m. Targeted shots were possible at a range of 150 or, which determined the tactical approach distance for light cavalry units. Ballistic shots could hit enemy units (without targeting individual soldiers) at distances of up to 400 m, useful for surprising and scaring troops and horses before beginning the actual attack. Shooting from the back of a moving horse may be more accurate if the arrow is loosed in the phase of the gallop when all four of the horse's feet are off the ground.

The Mongols may have also used crossbows (possibly acquired from the Chinese), also both for infantry and cavalry, but these were scarcely ever seen or used in battle. The Manchus forbade archery by their Mongol subjects, and the Mongolian bowmaking tradition was lost during the Qing dynasty. The present bowmaking tradition emerged after independence in 1921 and is based on Manchu types of bow, somewhat different from the bows known to have been used by the Mongol Empire. Mounted archery had fallen into disuse and has been revived only in the 21st century.

Jin dynasty
The Mongols encountered and used gunpowder weapons during their wars against the dynasties of China. In 1232 the Mongols laid siege to the Jin capital of Kaifeng and deployed gunpowder weapons along with other more conventional siege techniques. The Jin defenders also deployed gunpowder weapons such as fire arrows launched using a type of solid-propellant rocket. Another interpretation of the passage suggests they were fire lances that shot off flames. Jin scholar Liu Qi (劉祈) mentions the defenders using a type of bomb known as the heaven-shaking-thunder bomb (震天雷) that caused “many casualties, and when not wounded by the explosions were burnt to death by the fires they caused.” A description of the bomb in the History of Jin describes it as an iron container filled with gunpowder that could be heard from an extreme distance when it landed and caused fires that could penetrate iron armour. The Ming dynasty official He Mengchuan encountered a cache of these bombs three centuries later in the Xi'an area and described their appearance: they were made of cast iron and looked like two bowls that came together to form a ball that had a small hole at the top about the width of a finger. He wrote that that iron shrapnel came out when the bombs exploded and that was how they killed.

Heaven-shaking-thunder bombs, also known as thunder crash bombs, were used in 1231 by a Jin general named Wanyan Eke. He had lost the defense of Hezhong to the Mongols and fled on ships with 3,000 of his men. The Mongols pursued them with their ships until the Jin broke through by using thunder crash bombs that caused flashes and flames. During the siege of 1232, the Mongols protected themselves with elaborate screens of thick cowhide while they attacked the city walls but the Jin defenders lowered the bombs using iron cords until they reached the place where the miners worked. The protective leather screens were destroyed along with the excavators. Another weapon the Jin employed was a version of the fire lance called the flying fire lance or “flying-fire spears”. The History of Jin describes the gunpowder weapon as a tube made of sixteen layers of “chi-huang paper” around two feet in length. It was stuffed with gunpowder and iron shrapnel attached to a fuse. When lit, it shot out flames over more than ten paces. The tube was re-usable. It was recorded that Mongol greatly feared the flying fire lance and heaven-shaking-thunder bomb. In 1233, a group of 450 Jin fire lancers led by Pucha Guannu snuck up on a Mongol encampment and surrounded them by river, drowning 3,500 of the Mongol forces as they fled. After the death of the Jin emperor in 1234, a Jin loyalist gathered all the metal he could find in the city he was defending, including gold and silver, and made explosives to lob at the Mongols.

Song dynasty
In 1237, the Mongols attacked the Song city of Anfeng (modern Shouxian, Anhui Province) with bombs so large they required several hundred men to hurl. Towers that were hit by the bomb were immediately destroyed. The Song defenders, led by Du Gao, also used a type of bomb called the "Elipao," a type of local pear probably in reference to the shape of the weapon. The Anfeng defenders were also equipped with a type of small arrow to shoot through eye slits of Mongol armour, as normal arrows were too thick to penetrate. In 1257 the Song official Li Zengbo remarked during a frontier arsenal assessment of Jinjiang that they were not well equipped. Li considered an ideal city arsenal to include several hundred thousand iron bombs and also its own production facility to produce at least a couple of thousand a month. In one arsenal he found "no more than 85 iron bomb-shells, large and small, 95 fire-arrows, and 105 fire-lances. This is not sufficient for a mere hundred men, let alone a thousand, to use against an attack by the ... barbarians."

Blocking the Mongols' passage south of the Yangtze were the twin fortress cities of Xiangyang and Fancheng. What resulted was a siege that lasted from 1268 to 1273. For the first three years the Song defenders had been able to receive supplies and reinforcements by water, but in 1271 the Mongols set up a full blockade with their navy, isolating the two cities. A relief convoy led by Zhang Shun and Zhang Gui ran the blockade. They commanded a hundred paddle wheel boats. Despite travelling by night, they were discovered early on by the Mongols. When the Song fleet arrived near the cities, they found the Mongol fleet to have spread themselves out along the entire width of the Yangtze without any gaps. A chain was stretched out across the water. The two fleets engaged in combat, and the Song opened fire with fire-lances, fire-bombs, and crossbows. The Song forces suffered heavy casualties trying to cut through the chains using axes, pulling up stakes, and hurling bombs. They ultimately succeeded in reaching the city walls but in 1273, the Mongols enlisted the expertise of two Muslim engineers, one from Persia and one from Syria, who helped in the construction of counterweight trebuchets. These new siege weapons resulted in the surrender of Xiangyang in 1273.

During the siege of Shaoyang in 1274, the Mongol general Bayan waited for the wind to change to a northerly course before ordering his artillerists to bombard the city with molten metal bombs, which caused such a fire that "the buildings were burned up and the smoke and flames rose up to heaven." Shaoyang was captured and its inhabitants massacred. Bayan used bombs again in 1275 during the siege of Changzhou before storming the walls and massacring the inhabitants due to their refusal to surrender. In 1277, 250 Song defenders under Lou Qianxia conducted a suicide bombing and set off a huge iron bomb when it became clear defeat was imminent. Lou asked the Mongols for food in return for their surrender because they were starving. However after receiving the food and having a meal, the soldiers made noise with horn and drum as if to do battle, and set up off a large bomb that split the wall and killed many Mongol soldiers. In 1280, a large store of gunpowder at Weiyang in Yangzhou accidentally caught fire, producing such a massive explosion that a team of inspectors at the site a week later deduced that some 100 guards had been killed instantly, with wooden beams and pillars blown upward and landing at a distance of over 10 li (~2 mi. or ~3 km) away from the explosion, creating a crater more than ten feet deep. One resident described the noise of the explosion as if it "was like a volcano erupting, a tsunami crashing. The entire population was terrified." According to surviving reports, the incident was caused by inexperienced gunpowder makers hired to replace the previous ones, and they had been careless while grinding sulfur. A spark caused by the grinding process came into contact with some fire lances which immediately started spewing flames and jetting around "like frightened snakes." The gunpowder makers did nothing as they found the sight highly amusing, that is until one fire lance burst into a cache of bombs, causing the entire complex to explode.

Europe and Japan


Gunpowder may have been used during the Mongol invasions of Europe. "Fire catapults", "pao", and "naphtha-shooters" are mentioned in some sources. However, according to Timothy May, "there is no concrete evidence that the Mongols used gunpowder weapons on a regular basis outside of China."

Shortly after the Mongol invasions of Japan in the late 13th century, the Japanese produced a scroll painting depicting a bomb. Called tetsuhau in Japanese, the bomb is speculated to have been the Chinese thunder crash bomb. Japanese descriptions of the invasions also talk of iron and bamboo pao causing "light and fire" and emitting 2–3,000 iron bullets.

Kharash
A commonly used Mongol tactic involved the use of the kharash. The Mongols would gather prisoners captured in previous battles and would drive them forward in sieges and battles. These "shields" would often take the brunt of enemy arrows and crossbow bolts, thus somewhat protecting the ethnically Mongol warriors. Commanders also used the kharash as assault units to breach walls.

As they were conquering new people, the Mongols integrated into their armies the conquered people's men if they had surrendered - willingly or otherwise. Therefore, as they expanded into other areas and conquered other people, their troop numbers increased. Exemplifying this is the Battle of Baghdad, during which many diverse people fought under Mongol lordship. Despite this integration, the Mongols were never able to gain long-term loyalty from the settled peoples that they conquered.

Military units


In all battlefield situations, the troops would be divided into separate formations of 10, 100, 1,000 or 10,000 depending on the requirements. If the number of troops split from the main force was significant, for instance 10,000 or more, these would be handed over to a significant or second-in-command leader, while the main leader concentrated on the front line. The leader of the Mongols would generally issue the tactics used to attack the enemy. For instance the leader might order, upon seeing a city or town, "500 to the left and 500 to the right" of the city; those instructions would then be relayed to the relevant 5 units of 100 soldiers, and these would attempt to flank or encircle the town to the left and right.

The main point of these maneuvers was to encircle the city to cut off escape and overwhelm their enemies from both sides. If the situation deteriorated on one of the fronts or flanks, the leader from the hill directed one part of the army to support the other. If it appeared that there was going to be significant loss, the Mongols would retreat to save their troops and would engage the next day, or the next month, after having studied the enemies' tactics and defenses in the first battle, or again send a demand to surrender after inflicting some form of damage. There was no fixture on when or where units should be deployed: it was dependent on battle circumstances, and the flanks and groups had full authority on what to do in the course of battle, so long as the battle unfolded according to the general directive and the opponents were defeated.

Psychological warfare and deception
The Mongols used deception and terror by tying tree branches or leaves behind their horses. They dragged the foliage behind them in a systematic fashion to create dust storms behind hills to appear to the enemy as a much larger attacking army, thereby forcing the enemy to surrender. Because each Mongol soldier had more than one horse, they would let prisoners and civilians ride their horses for a while before the conflict, also to exaggerate their manpower.

Feigned retreat
The Mongols very commonly practiced the feigned retreat, perhaps the most difficult battlefield tactic to execute. This is because a feigned rout amongst untrained troops can often turn into a real rout if an enemy presses into it. Pretending disarray and defeat in the heat of the battle, the Mongols would suddenly appear panicked and turn and run, only to pivot when the enemy was drawn out, destroying them. As this tactic became better known to the enemy, the Mongols would extend their feigned retreats for days or weeks, to falsely convince the chasers that they were defeated, only to charge back once the enemy again had its guard down or withdrew to join its main formation. This tactic was used during the Battle of Kalka River.

Communication
The Mongols established a system of postal-relay horse stations called Örtöö, for the fast transfer of written messages. The Mongol mail system was the first such empire-wide service since the Roman Empire. Additionally, Mongol battlefield communication utilized signal flags and horns and to a lesser extent, signal arrows to communicate movement orders during combat.