The forces of the expanding Mongol Empire swept across the steppes of western Eurasia from 1236 to 1240, folding in many nomadic populations as they went. Along the way the Mongols also sacked and came to rule the cities of the Rus principalities, ultimately establishing what would become known as the “Golden Horde.” For the 1241 campaign season, Batu Khan, the Mongol commander who was directing the westward advance, set his sights on the Kingdom of Hungary. The kingdom was centered in the Great Hungarian Plain, a thumb-shaped extension of the Eurasian steppe, encircled by the Carpathian Mountains to the east and assorted other mountain ranges to the west, north, and south. King Béla IV of Hungary, aware of the wave of Mongol conquests just beyond the Carpathians, remained hopeful that the ring of mountains would prove defensible, especially after he had welcomed as nominal allies the Cuman Turks (also known as the Kipchaks or Pechenegs), who were fleeing the Mongols. The Hungarians, however, failed to reckon with their enemy’s enormously flexible and long-range operational capabilities. The Mongols didn’t campaign as a single force along predictable paths—they arrived everywhere at once.
One of the best accounts of the Mongol invasion of 1241 comes from Roger of Torre Maggiore, an Italian prelate known as “Master Roger” who was on assignment in the Hungarian city of Várad when it was captured by the Mongols. He described how the Mongol wave had first crested against the Carpathians the previous year, pushing the Cumans over the mountains into Hungary, and then, in a crucial hint of how the Mongols operated, how “they retreated to the distance of four to five days, leaving untouched the borderlands adjacent to Hungary, so that when they returned they would be able to find food and fodder for themselves and their horses and so that no news might reach the Hungarians about them.”
The Mongols’ logistics and operational technique went hand in hand. As the Mongol armies moved over fresh grasslands outside Hungary during their approach, the green pastures fed the horses in a way that sustained the soldiers for days afterward—a kind of logistical “running start”—as the fattened horses provided milk for the soldiers. Then, as the Mongol forces concentrated on the business of fighting, they were able to move almost entirely unencumbered by logistical considerations—at least for a week or so. Their blinding speed deprived their victims of any kind of advance warning.
The primary Mongol army under Batu, according to Master Roger, pressed through the “Russian Gate” (most likely the Verecke Pass in the Carpathians) and directly engaged the main Hungarian defenses. Meanwhile, a second Mongol force removed a potential Hungarian ally from action, blazing through Poland in three columns and uniting at Liegnitz (Legnica), in the southwestern part of the country, where on April 9, 1241, it defeated the Poles and Teutonic Knights. That army then turned south to enter Hungary from the north. Two further Mongol armies skirted the Carpathians to the south, entered the Hungarian basin by crossing the mountains through two other passes, and then turned north to ravage the plain and unite with the other Mongol columns. These coordinated movements took place within days of each other, and they swept all before them, ultimately pursuing the Hungarian king to an island in the Adriatic. Master Roger’s account is a veritable succession of “meanwhiles”—the Mongols were seemingly in simultaneous motion everywhere.
It is now widely accepted, even assumed, that military activity has three levels: tactical (how troops act in combat); operational (how forces are moved in space and time to gain an advantage at the moment of contact); and strategic (how leaders allocate resources and determine a target or targets that will lead to the submission or destruction of an enemy). For much of history, armies marched along relatively linear and predictable paths from their own usually urban point of mobilization to some point within enemy territory where they could apply pressure, either by destroying crops and villages or by laying siege to a major urban center. The concentration of wealth, population, and political authority in cities—authority both real and symbolic—made them frequent targets, but cities were usually also fortified, if not literally then by the natural density of the defending population. In many ways, therefore, the real function of an attacking army was often to “deliver the siege”—protecting its troops and the matériel that would accomplish that critical work. The defender’s army of course sought to interrupt the attack.
Strategic planning typically involved deciding first what the point of pressure would be: enemy territory, enemy cities, or perhaps the concentration of enemy forces in a defending army. At the moment of contact, generals would consider the appropriate tactics for the local terrain and the nature of the troops involved. But between the strategy and the tactics were simply marching and logistics. Because traveling in a single large unit was safer, most armies avoided splitting into smaller pieces. “Operations” as such were confined to movements from point A to point B, perhaps with a small, localized cloud of raiding and foraging forces that didn’t stray far from the main unit. The defender’s army, not knowing where the attacker would show up, was often forced to divide into smaller units to man frontier garrisons or observation posts. Fortunately for the defender in a conflict between adjoining states, most paths were relatively predictable. In short, for an attacking or invading force, the operational level of war under these conditions usually involved the movement of a single combat element, with some screening or obscuring forces occasionally changing direction and using a mountain or river to hide the intended route or ultimate target. None of these actions required the coordination of multiple independent combat elements moving separately across the campaign space.
There were some striking exceptions to this pattern before the late 18th century, especially in armies that could naturally divide into independent elements. The legions of Rome provide a notable example: Caesar regularly dispatched cohorts on independent operations within Gaul in the 50s bce. Many Chinese armies seem to have had this capability as well, although even the massive clashes of the Warring States era (475–221 bce) generally followed the same pattern of single armies fighting over specific urban objectives, often after one army followed a predictable route of attack. Even Sun Tzu’s legendary aphorisms mostly seem to apply to a state with a single army moving on a single axis of advance. Later armies in the internal wars of China may have been so big as to necessitate independent operations. But a study of the campaigns of Sparta against Athens, or Alexander in Persia, or Edward III in France, or even Frederick the Great’s almost desperate maneuvers in his 18th-century wars quickly reveals the limited extent to which major “detachments,” or separate forces within the same army, coordinated movements with a single strategic objective.
In Europe this pattern changed only under the pressure of ever-larger armies (as it likely had in China). Most famously, Napoleon mastered the art of moving many independent corps d’armée along separate but coordinated paths, devising ways to use the logistical limitations he encountered to his advantage. His operational goal was to achieve an advantage in a decisive battle of annihilation. That battle would destroy the enemy’s armed forces and render the defending state existentially vulnerable. In Napoleon’s wars, submission and a forced alliance quickly followed, with some states politically obliterated. Napoleon, like his 18th-century predecessors, was solving not so much a campaign geometry problem as a logistical one: Only so many thousands of troops could be sent down a single axis of advance and still move and eat. In the process of wrestling with this problem, he discovered operational art.
This notion of an operational art became ever more sophisticated as weapons systems and their associated logistical requirements proliferated in the 20th century. To some, World War I appeared to be a massive failure of operational technique. It was followed by a surge of interest in new possibilities for restoring operational maneuver suggested by tanks and the internal combustion engine. British, Soviet, and German theorists looked for new ways to move military assets that would allow multiple operations to be combined for maximum strategic effect. In the postwar United States, however, a kind of stagnation set in as the immense power of nuclear weapons seemed to render ground maneuver irrelevant.
Ultimately, in the wake of the failure in Vietnam, the U.S. Army, after a period of critical reflection, determined that its leaders had lost touch with operational art and vowed to relearn it and train for it.
Or at least this is the story as it’s usually told. Far too much military history is not only too Europe-centric but also too state-centric. And even analyses of nonstate warfare too often focus on tactical techniques rather than strategic acumen or operational skill. To be fair, this is in part a source problem. When Native Americans attacked European forces, for example, the witnesses who recorded the events were generally the Europeans, who focused on the fighting rather than on the strategic intent of their adversaries. Fortunately, some of the Eurasian nomads created territorial empires, established bureaucracies, and wrote histories that clarified their strategic goals, especially once they had become imperial powers. Nonetheless, historians have tended to focus on these nomads’ tactical skills as horsemen and archers rather than looking at their campaigns as a series of connected events designed to support a military strategy, which in turn supported a political goal. In many ways, however, as with Napoleon’s corps d’armée, the steppe nomads made a virtue of necessity, maneuvering large independent forces across long distances and wide spaces, and they did so while conforming to the iron laws governing the logistics of grass.
Nomads on the Eurasian steppe moved because they had to. Moving served the vast pasture needs of their herds of sheep, goats, yaks, and horses. Though seemingly an endless grassland, the steppe was relatively arid. Its grasses grew slowly, and seasonal temperature variations were severe. The animals periodically had to be moved to new pastures, at least seasonally, and under normal conditions it was not feasible for too many people to live too close together: A few people required many animals, and many animals required vast quantities of grass, and that grass could quickly disappear. The herds provided meat, skins, and dairy, the first two of which (along with horses) could be traded for goods and grains from sedentary peoples. The usual mode of life was the small familial camp of eight to 50 people, surrounded by their herds and migrating seasonally either from north to south or from low elevation to high. They did not “wander,” however. Families or groups of families (clans) had customary pastures, and human or nature-induced threats to those customary claims could lead to war.
Napoleon found ways to use the logistical limitations he encountered to his advantage.
Under the pressures of war, strong leaders could assemble a confederation of clans, some merely turning to predatory raiding of fellow nomads or nearby farmers, but the most successful could convert local success into regional ambition, and then beyond; some ultimately pursued the conquest of more distant parts of the steppe or even the sedentary world. These conquest migrations have sometimes been attributed to climatic pressure, but they were also often a political requirement of success itself: A nomadic chief who had gathered the reins of numerous clans under his leadership needed to reward them to retain them. Success did not just breed success, it demanded it. There are many examples of steppe confederations, some of which became imperial rulers over sedentary lands. There is some evidence of this nomadic style of warfare even among the ancient Scythians—nomads on the western steppes bounding the classical Greek and Persian worlds. But the best evidence comes from the Mongol expansion, and the following examples derive from the period of imperial expansion after the rise of Temujin to rule the united Mongol tribes, who elected him to be Chinggis Khan in 1206, and continuing through the first generation of expansion after his death in 1227.
The nomad story always begins with grass. While large conglomerations of nomads could not remain together in a single location for long, war required the concentration of men and horses. The challenges of that scenario mostly had to do with the calories in a steppe warrior’s ration and the acres of grass required for a large herd of horses. Unlike state-based armies, nomadic forces had no notion of a daily “official” ration, but one can start with the rough calorie count associated with European state armies: about a pound of meat and a pound of bread per day. According to modern calorie calculators, and assuming the meat is fresh, such a ration would provide just under 2,000 calories a day. This diet would have been fleshed out by alcohol rations and small portions of cheese, butter, peas, and so on.
Eurasian steppe nomads on the move generally subsisted on horse and sheep dairy products. They fermented the mare’s milk into a beverage called airag in Mongolian, qumis in Turkish, and they churned the sheep’s milk into yogurt or a cheese paste or curd. To this foundation they added mutton and other meat from whatever animals they could hunt.
Eurasian steppe nomads on the move generally subsisted on dairy products.
The mix of dairy and meat, which varied over the course of the year, provided a substantial amount of calories. Beginning with the mutton, we can use a generous figure of 60 pounds of meat per sheep, at 1,340 calories per pound. Mare’s milk is also highly caloric, but the mares produced it in varying amounts depending on the season. Foaling season lasts from mid-June to early October. One modern estimate suggests that a mare will produce approximately 2.3 quarts per day above what the foal needs, and at 280 calories per cup that’s 2,688 calories per day.
These calculations are supported by a near contemporary Chinese source that suggested that one mare could produce enough milk per day for three men. The amount of meat or milk a Mongol warrior ate per day would depend on the season—more milk in foaling season; more meat after the sheep fattened and as winter approached. Even so, we can combine them into a kind of average and suggest that a half pound of mutton per day and two quarts of the highly caloric airag per day, varying slightly with the seasons, would provide at least 3,300 calories—well above contemporary Western ration standards.
That warriors were drinking at least that much airagper day was suggested by John of Plano Carpini, a medieval monk who traveled deep into the Mongol Empire as an emissary to the khan in the late 1240s, and who pointedly observed that the Mongols drank “great amounts” of airag every day during the foaling season. William of Rubruck, another European traveler in the Mongol Empire, agreed that during late spring, summer, and fall mares’ milk was the primary food. Rubruck suggested that a single sheep could feed 100 men, a figure that matches our calculations here quite neatly, as a sheep could indeed provide 120 half-pound portions.
Historian David Morgan found evidence that a full campaign season might demand 30 sheep per soldier, though another source suggests that the entire Kwharazm campaign (roughly encompassing modern Afghanistan, Iran, Turkmenistan, Uzbekistan, and more, lasting from 1219 to 1221) required only three dried sheep per 10 men. Furthermore, none of these calculations include the yogurt that could be produced from the sheep’s milk or the additional meat supplied by hunting.
This very modest amount of food provided a lot of calories. But how many animals would be needed to meet even this fairly minimal requirement? And ultimately, how many acres of grass would those animals need?
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The documentary record for the Mongols on campaign varies, suggesting that each warrior brought along as few as two and as many as 18 horses. That’s an enormous variation, but most historians have settled on five or six, mostly mares, with some geldings. In addition, at least during the Mongol imperial campaigns, there is solid evidence for sheep being brought along with the army, even on its more rapid movements.
The more limited evidence from other steppe peoples, who had similar subsistence and logistical systems, supports this use of sheep even when on the move. The ancient Greek historian Herodotus, for example, hints at the ready availability of flocks of sheep kept near the army in his account of the nomadic Scythians’ defense against Persia. The historian John Masson-Smith Jr. suggests that Mongol armies used essentially two kinds of logistical arrangements. One was for the relatively fast operational columns, primarily sustained by its horses and possibly some sheep (what we might call pure “horse-string logistics”). The other was the army accompanied by its a’urughs—the host of women, flocks, and ox-drawn carts, some of which would bring siege equipment.
Campaign operations, including the Hungarian invasion already described, were conducted at the leading edge of larger movements and were therefore primarily horse-string logistics. The Mongol army wintering in the western steppe in 1240, for example, was probably sustained by the full a’urughs, but when they then moved toward Hungary in 1241, first across those four or five days of carefully husbanded grass and then across the Carpathians, they probably did so almost purely based on horse-string logistics. In terms of food production, five horses and one sheep per soldier would produce approximately 120 days of meat (at a half pound per day—obviously sharing the sheep among a group of men and then killing another messmate’s sheep and so on) and 280 days of airag. The normal maximum load for a steppe horse is about 100 pounds (the rider rotated mounts to rest the horses). Taking into account that some milk would accumulate during the period when the horses produced more milk each day than could be drunk, this calculation dovetails well with the documentary record of a five-horse string per warrior: one to be ridden, two to carry loads (accumulating airag, drying meat, armor, and so on), and two resting without loads.
These numbers answer the first question: Five horses and one or two sheep could sustain a steppe warrior for a campaign season extending for as much as two-thirds of a year. But how much grass did even that minimal amount require? Steppe horses are unique in that they require only grass for sustenance, and sheep are similarly hardy and adaptable. And if you ask modern-day Mongolian nomads how much grass their herds need, they tend to answer, “It depends.” And indeed it did depend—especially on campaign—as the terrain changed or the weather shifted and, given the scope of Mongol campaigns, as lines of latitude were crossed.
But even if we avoid the complex and uncertain math needed to determine how many acres of grass per horse were necessary in a given year, we can turn to some key documentary evidence to show how royal nomadic households not involved in military actions had to move and spread out. Christopher Atwood has reconstructed an itinerary for Ong Qa’an, a 12th-century ruler of the Kereids, a Turco-Mongol tribe that was later defeated by Chinggis Khan and incorporated into the Mongol confederation.
As Ong Qa’an moved his army along a seasonal migration route, he divided it into three forces: the chiefly entourage itself and the “left” and “right” wings. This was not a campaign, although Ong Qa’an was on alert, so the division was likely a simple necessity of pasture.
In a similar way, Batu’s royal camp (ordo) in the western steppes after the conquest of Hungary—which it must
be emphasized was a vast conglomeration of people—received its daily ration of mares’ milk from 30 satellite encampments, each a day’s journey away and each shepherding 100 mares. In an illuminating contrast, the ruling successors to Chinggis Khan used a different kind of imperial itinerancy. Their movements were designed to project political power over territory they had already conquered. It was neither the necessary mobility of pastoral subsistence nor the planned mobility of the army on campaign. As a deliberate political move of a large population (the royal court and bodyguard), it did not necessarily follow the seasons, and therefore the khans had to build a logistical infrastructure to import the food that each encampment needed.
Their movements were designed to project power over already conquered territory.
For smaller steppe forces in intertribal wars, the pasture limits would have been relatively easy to manage, provided that the forces kept moving. With confederation and conquest, however, steppe armies grew to the point that they had to be divided while they moved. Although debate remains on the exact size of Mongol campaign armies, the math of pasture requirements makes clear that their conquest armies of at least tens of thousands simply had to spread out on the steppe to sustain themselves, and they had to be kept moving. Fortunately for the Mongols, there was already a long steppe tradition of subdividing troops into units of 10, 100, 1,000, and 10,000—in Mongolian, these units were called arban, jaghun, minquan, and tümen (pl. tümet), respectively. Although, as in much of military history, such unit sizes were an unrealized ideal, they established a relatively uniform mechanism for distributing forces across the landscape, one tümen here, one there, and so on, unlike the ad hoc units in contemporary medieval armies whose sizes simply corresponded to the political clout and personal retinue of their leading nobles. Tümen commanders were major figures in the imperial army, and when our sources indicate the arrival or departure of an important name, it generally indicates the movement of that person’s tümen as well.
Another aspect of the nomadic lifestyle lent itself to distributed military operations. The communal nomadic hunt—a central political and cultural institution on the steppe—proceeded as a vast line of horsemen, moving across the plains, driving animals before them, with the far ends of the line advancing more quickly, and curving in toward each other, slowly converting the line into a circle. The horsemen would drive the animals into an ever-decreasing space until a royal order was given to begin the killing. This form of hunting drive, known as the nerge, proved adaptable to both tactical and operational level wartime applications. A royal hunt might have a line whose two ends were invisible to each other over the horizon, so nomads regularly practiced moving in a coordinated manner, even when out of sight of each other. The Mongols, and presumably other nomadic armies, seem to have scaled up the nerge to its operational equivalent, imagining their distributed tümet moving long distances to dislodge, disrupt, and ultimately surround their slower-moving, often unitary enemy.
The Mongols adapted a hunting drive known as the nerge into a military tactic.
Accounts of other nomadic peoples’ campaigns suggest how the logistics of grass and consequently of distributed operations were common, at least when army sizes rose to high enough levels. Herodotus’s account of the Scythians defending their homeland against a Persian invasion, for example, seems to show how the nomads could use their ability to easily separate and reunite in defensive operations on the steppe as well, particularly since it seems clear from his account that the Persian army advanced in the usual manner of sedentary states—as a single unitary army. Once on the steppe the Persians found themselves chasing a divided Scythian army that devastated the landscape in front of them while retreating deeper into the steppe. At one point when the Persians pursued a Scythian force and could not catch it, they found themselves drawn into a futile chase, incidentally incurring the wrath of other, previously neutral tribes. Herodotus repeatedly tells us how the Scythians changed directions, divided and reunited, and at one point operated in at least three separate divisions that could concentrate to hit the demoralized Persian army or make a surprise move toward the bridge guards the Persians had left behind.
Returning once more to the Mongols, we can see a full season of offensive campaigning, including the launch from a distributed winter camp into distributed divisional (tümet) operations in Hülegü Khan’s (Chinggis’s grandson) march on Baghdad in 1257 and 1258. The broader campaign began much earlier, in 1255, as Hülegü and the army departed Mongolia, with a broad array of scouts and imperial officials preceding them to secure pasturage on the long march across the steppe to the jumping-off point on the south shores of the Caspian Sea. Mongol occupation forces in between were literally moved aside to leave their normal pastures available for the passage of the royal army. During this long slow march, the army was accompanied by its full “baggage,” the a’urughs, although in some stages of the campaign the army surged ahead for a month or more in short offensive campaigns, primarily against the strongholds of the Assassins, an Islamic religious military order based in Persia.
Finally, in the winter of 1256–1257, Hülegü went into a winter camp near the southern shores of the Caspian, although we should assume that this was a distributed camp, with forces dispersed around the countryside. In John Masson-Smith’s reconstruction of the campaign, it becomes clear that although our main documentary sources followed the royal army as if it were a single body, in fact the full army had traveled in separate bodies. Additional tümet appear in the records, presumably having marched separately from the royal army, or even arriving from other parts of the empire, until ready to fall under Hülegü’s direct command for the approaches to the Assassins, and then ultimately to Baghdad. In addition to Hülegü’s semiconsolidated army on the Caspian, two additional tümet arrived from the west, presumably from Anatolia, and approached Baghdad from the north. For the final march on Baghdad, Hülegü divided his own army into three wings (left, right, and royal center), and each approached the city from a different direction, dislodging defenses and leaving the caliphate’s forces uncertain as to where the main threat came from. The end was nearly a foregone conclusion, awaiting only the outcome of the siege—a siege enabled by the slow movement of the a’urughs, which had brought the equipment and which was manned by the sedentary soldiers and “arrow fodder” troops of already conquered peoples.
The Mongol imperial armies, and very likely their steppe predecessors and successors, were thus natural practitioners of synchronized separate operations in pursuit of a single strategic objective. The logistics of grass encouraged the wide distribution of forces. The traditional tactics of the hunt lent their shape to widely spaced operations of encirclement. In combination, those operations produced decisive strategic results.
Some historians have suggested that these techniques and capabilities persisted among steppe peoples into the 19th century, influencing the Russian military and perhaps ultimately even affecting the later emergence of operational art in the Soviet Union after World War I. As the Russian Empire of the 19th century expanded across the steppe, it encountered and struggled with an array of nomadic steppe peoples—Uzbeks, Kazakhs, Mongols, and more, many of them still claiming direct political and lineal descent from the empire of Chinggis Khan and many of them still fighting in the steppe nomadic cavalry style. To cope with the mobility of these forces and with the distances involved, the Russian army had to adapt, and much of it grew to resemble steppe cavalry. Their experience with the nomads’ vast, self-sustained, sweeping movements designed to encircle and harass slower-moving sedentary armies, found its way into the Russian imperial military’s training program.
A Russian study of the nomadic way of war, first published in 1846 and revised in 1875, was used as a textbook at the Russian General Staff Academy (officially the Nicholas General Staff Academy). Through this study, the nomadic way of war likely influenced key figures in the early Red Army, especially Marshal Mikhail Tukhachevsky. “Over…three centuries the idea of using mobility and mass to hit deeply and decisively,” historian Bruce Menning
observes, “has remained a surprising constant in Russian military thought—if not always in practice.” Menning specifically points to a long history of Russian armies using large independent forces of cavalry to strike deep in the enemy’s rear and sow confusion.
Much of the rest of the story is more widely known. Tukhachevsky and his followers worked out a theory of “deep battle,” partly in response to the stalemate of World War I but heavily influenced by the challenge of operating over the long distances of the Eastern Front. The objectives of deep battle closely matched the Mongol methods: deep penetrating columns that would dislodge defenders, disrupt their ability to respond, and surround them, all while logistically self-sustaining during the deep penetration. These ideas in turn influenced the emergent armor theorists of the interwar German army that trained in the Soviet Union in the 1930s, at a time when the Treaty of Versailles banned the German army from having tanks. German bewegungskrieg (maneuver warfare), popularly known as blitzkrieg, followed its own doctrinal path and certainly became more famous. In reality, however, the fully developed Soviet doctrine was far more sophisticated and was more realistically attuned to the problems of logistics and successive combined operations. Ultimately, it was the Soviet formulation of “operational art” that would find its way slowly into the books and manuals and then the training of the American army of the 1980s. All because of the logistics of grass.