As Islam was embroiled with its counter-crusade against the Christian infidel in the Holy Land, a new, more ominous threat was emerging from the east. Mongol and Turkish tribesmen, under the charismatic leadership of the Mongol warlord Temuchin (1167–1227), were massing for the greatest conquests in human history. Genghis Khan (the title Temuchin took in 1206) and his powerful nomadic confederation swept out of Mongolia and conquered northern China and Korea by 1216, then spread westward across central Asia to invade Persia. By the end of 1221 Genghis Khan had crushed the Islamic Khwarizmian Empire in Transoxiana and invaded the Ukrainian steppes. There, in 1223, a combined army of Kievan and allied Asian nomads turned back the Mongol invaders at the battle of Kalka River. Genghis Khan died in 1227 before he could avenge this defeat, but he had already created the largest contiguous land empire yet seen in human history.
The secret of the Mongols’ military success was a combination of strategic mobility, effective tactics and the quality of the Mongol warrior and mount. Consisting entirely of light and heavy cavalry (with the exception of some auxiliary units), the Mongol army was organized on the decimal system. The largest manoeuvre unit was the tuman, consisting of 10,000 men. Three tumans (30,000 men) normally constituted a Mongol army. The tuman itself was composed of ten regiments or minghans of 1,000 men each. Each minghan contained ten jaguns or squadrons of 100 men. The jagun was further subdivided into ten troops of ten men called arbans. This novel tactical flexibility allowed the Mongol army to strike with the speed and force of a hurricane, confusing and then destroying its enemies, then disappearing back into the grasslands like its Scythian, Magyar and Seljuk forebears. Though often described as a ‘horde’ of warriors by their civilized adversaries, the Mongol army was usually much smaller than that of its opponents. In fact, the largest force Genghis Khan ever assembled was less than 240,000 men, sufficient for his conquest of Transoxiana and north-west India. The Mongol armies which later conquered Russia and eastern Europe never exceeded 150,000 men.
The typical Mongol army was a pure cavalry force consisting of about 60 per cent light cavalry and 40 per cent heavy cavalry. These two weapon systems co-operated in an unprecedented manner to bring to bear the strengths of missile and shock combat against the enemy. Mongol light cavalry were required to reconnoitre for the army, act as a screen for their heavier counterparts in battle, and provide missile fire support in attacks, and follow-up pursuit once a battle was won. These light horsemen were armed in characteristic Asiatic fashion with two composite bows (one for long distance and one for short), two quivers containing at least sixty arrows, two or three javelins and a lasso.
The Mongol composite bow was larger than most of its central Asian cousins, with a hefty pull of up to 165 pounds and an effective range of 350 yards. Quivers carried arrows for many purposes: light arrows with small, sharp points for use at long ranges, heavier shafts with large, broad heads for use at close quarters, armour-piercing arrows, arrows equipped with whistling heads for signalling and incendiary arrows for setting things on fire. The Mongol warriors were so adept at mounted archery that they could bend and string the bow in the saddle and then loose the arrow in any direction at full gallop.
The Mongol light trooper usually did not wear hard body armour, though he did often wear a padded gambeson and employ a wicker shield covered in thick leather. In combat, he replaced his thick woollen cap with a simple hardened leather or iron helmet if available. Mongol heavy cavalry were better protected, with warriors wearing leather, mail or lamellar cuirass and metal helmet, and their mounts wearing leather barding. The primary weapon of the heavy cavalryman was a 12 foot lance, though curved and straight sabres and small battleaxes and maces were also present among the elite. All warriors were required to wear a long, loose raw silk undershirt next to their skin for added warmth and protection. If an enemy arrow penetrated the steppe warrior’s body, it would usually fail to pierce the silk, instead carrying the resilient fibre with it into the wound. By simply pulling on the silk, a field surgeon could easily extract the arrow.
Military service was compulsory for all Mongol adult males under the age of sixty, and like all steppe societies, there was no such thing as a civilian. Nearly born in the saddle and raised to be effective mounted hunters and herders, these Mongol warriors were inured to the hardships of the Eurasian steppes, facing extremes in weather and lacking the luxuries, rich food and soft mattresses of sedentary living. This harsh lifestyle forged warriors with strong minds and bodies, capable of almost superhuman endurance in the saddle. On the march, each tuman had its own herd of remounts following behind, with each steppe warrior having at least three remounts. This allowed him to ride at speed for days, slowing only to tap a vein in the weakest horse for nourishment. Mongol troopers were responsible for their own food and equipment, cutting down the size of the supply train and virtually abolishing the need to maintain a base camp.
The horses themselves were also very highly trained, with Mongol warriors preferring mares over stallions as warhorses. The Mongols’ original mounts were what are known today as Przewalski’s horses, thick and strong beasts with broad foreheads, short, powerful legs, and a reputation throughout the steppes for their courage and stamina. Broken and ridden hard for their first two years, these horses were then put out to pasture for the next three years to develop a herd mentality. Afterwards, they were trained for warfare. After the fall of Khwarizm, these horses were crossbred with the larger, hot-blooded Arabian breeds, creating a larger mount of between 14 and 15 hands, with some as large as 16 hands. These warhorses were treated as comrades-in-arms. Horses ridden in battle were never killed for food, and when old or lame, were put out to pasture to live out their last days. When a warrior died, his mount was sacrificed and buried with him so that he would have a companion for the afterlife.
Mongol commanders understood the importance of the principles of surprise, offence and manoeuvre in military operations, of seizing and maintaining the initiative in battle, even if the strategic mission was defensive. When a Mongol army was on campaign, each tuman usually advanced quickly on a broad front, maintaining only courier contact in between the 10,000-horse divisions. To facilitate good communication between field armies and headquarters, permanent staging posts or yams were established behind advancing armies at approximately 25 mile increments. These yam stations acted as a kind of pony express for the Mongols, giving commanders the ability to send messages back and forth at the rate of 120 miles per day. When the enemy was located, information concerning his strength, complement, position and direction of movement was relayed back to headquarters, and in turn disseminated back to local commanders. Once intelligence had been gathered and the plan co-ordinated, the main force converged and surrounded the adversary, while other elements continued to advance and occupy the country behind the enemy’s flank and rear, threatening their lines of communication. If the enemy force was small, it was simply destroyed, but if it proved formidable, then Mongol generals used manoeuvre, terrain and their enemy’s predilections to best advantage.
If the enemy army was stationary, the Mongol general might command his main force to strike it in the rear, or turn its flank, or engage and then feign a retreat, only to pull the enemy into a pre-planned ambush using an elite light cavalry corps called the mangudai or ‘suicide troops’ (an honourable title more than a job description). The function of the mangudai was to charge the enemy position alone, and then break ranks and flee in the hope that the enemy would give chase. If the enemy pursued, the Mongols would lead them into terrain suitable for ambush.
If the enemy’s position was not precisely known, the main Mongol army advanced along a broad front in several roughly parallel columns behind a screen of light cavalry. The main force galloped along in five ranks, the first two of which were heavy cavalry and the last three light cavalry. Riding way out in front and on either flank were three separate light cavalry detachments. When the enemy was encountered, the Mongol army reacted quickly. The contacted outriders automatically shifted to protect the main force as it wheeled to meet the threat. Once the vanguard was engaged, the light cavalry in the main force galloped through the ranks of the heavy cavalry and joined the other horse archers. What took place next was a classical employment of missile and shock combat reminiscent of the battles of Carrhae and Dorylaeum centuries earlier.
Co-ordinating the attack in an unnerving silence without battle cries or trumpets (signals were given by flags), the Mongols began their assault with light cavalry riding up and down the enemy’s front lines, showering his ranks with well-aimed javelins and arrows. Once light cavalry missile-fire had thinned the enemy’s ranks, the horse archers broke away to either flank, leaving the heavy cavalry to drive in the final blow. Mongol lancers usually advanced at a trot and in silence. It was only at the last possible moment that the charge was ordered by striking the great naccara, a large kettledrum carried by a camel. With a single blood-curling scream, the Mongol heavy horse attacked.
In combat, the Mongols would close in from many directions if possible, taking advantage of any disorder or confusion their swarming tactics created. The famous thirteenth-century Italian merchant and Eurasian traveller Marco Polo gives us a description of Mongol tactics, though he called the Mongols by the generic name of Tartars:
When these Tartars come to engage in battle, they never mix with the enemy, but keep hovering about him, discharging their arrows first from one side and then from the other, occasionally pretending to fly, and during their flight shooting arrows backwards at their pursuers, killing men and horses, as if they were combating face to face. In this sort of warfare the adversary imagines he has gained a victory, when in fact he has lost the battle; for the Tartars, observing the mischief they have done him, wheel about, and make them prisoners in spite of their utmost exertions. Their horses are so well broken-in to quick changes of movement, that upon the signal given they instantly turn in every direction; and by these rapid maneuvers many victories have been obtained.
Sometimes, Mongols would even send out small detachments to start large prairie fires or set fire to settlements to deceive the enemy or mask movements.
Another area of success for the Mongol war machine was its ability to reduce walled cities, thereby leaving no enemy strongholds in the wake of their conquests. After initially developing a train using Chinese siege weapons, equipment, techniques and operators, the Mongols soon made their own improvements and developed their own techniques. The Mongols were also quick to include in their siege train weapons encountered in their conquests. From the Chinese, the Mongols adopted the torsion-operated light and heavy catapult, and from the Khwarizm, they adopted the tension-operated ballista and a central Asian version of the trebuchet, a powerful engine operated by counterpoise.
Like all cavalry-based armies, the Mongols preferred an open field engagement over siege warfare. But if an enemy city refused to open its gates, Mongol generals had numerous ways to gain access. Siege weapons, towers and battering rams were brought to bear, but if these techniques proved ineffective, the Mongols would often attempt to set the city on fire, compelling the inhabitants either be burned alive, or to open their gates. If the wall was breached, a favourite but ruthless Mongol tactic was to herd captives in front of their own dismounted troopers, forcing the defenders to kill their own countrymen in order to bring fire on the attackers.
Once the Mongols took the city, it was pillaged and its garrison and inhabitants were often put to the sword. Genghis Khan routinely eradicated entire populations in his campaigns against the Khwarizmian Empire, depopulating and destroying Balkh, Merv and Nishapur along the way. Men, women and children were separated, distributed like cattle among the tumans, and decapitated. Their heads were then stacked in pyramids to serve as monuments to Mongol cruelty and warnings to the steppe warriors’ enemies. Even the dogs and cats were killed. The Mongols spared prisoners, artisans, engineers and men of military age so that they could assist in the next siege, digging trenches, building ramparts or acting as fodder for the assault.
The Mongols used their catapults, ballistae and trebuchets not only against city walls, but also against enemy field positions. These artillery pieces shot containers filled with burning tar to create smoke screens, or firebombs and grenades to create tears in the enemy’s lines. The Mongols also perfected a medieval version of a ‘rolling barrage’, with cavalry units advancing under catapult and ballista fire. The Mongols even made use of rudimentary rockets made from bamboo wrapped in leather, though these weapons were very inaccurate and unreliable.