The Military Transformation Of Medieval Europe: Stirrups vs Social Cohesion

The historical consensus holds that the invention of the stirrup was a major development in military history. By permitting the horseman to keep his seat, the simplified story goes, the stirrup changed the dominant strategy from the infantry-based armies of antiquity to the shock cavalry-based armies that came to dominate in the middle ages.

This story seems to make sense. The change in the composition of European armies is real and needs to be explained. (Infantry remained the numerical majority of most armies, but heavy cavalry became more important in determining the outcome of battles.) Horsemen without stirrups used different equipment in different ways than the stirrup-using knights we’re familiar with. The cavalry charge against massed infantry is almost unheard of in antiquity but becomes an extremely important tactic from the early middle ages until well after the ubiquity of firearms.

However, there is no historical consensus on when the stirrup became important in Europe. I’ve seen serious claims ranging from the late 300s to the late 700s. There’s sharp disagreement over very basic claims, like “Was the Battle of Adrianople a triumph of cavalry over infantry?” or “Did the Carolingian military use stirrups?” The history of the stirrup before it reached Europe, e.g. in India or central Asia, is no clearer.

This is super weird. If the stirrup was such a huge deal, shouldn’t we be able to see its effects? If a historian in the year 3000 were trying to date the advent of the machine gun, and only had fragments of secondary sources and doubtful archeological scraps, it would still be possible because the machine gun so greatly transformed strategy, tactics, and the experience of individual soldiers. (The American Civil War is the only case I can think of where a smart scholar might get the wrong answer.) This is what we see for other massive shifts in historical weapons, such as chariots, castles, and artillery. If the stirrup were anywhere near this important, its effects should be similarly visible.

I’ve read all these historians arguing about the minutiae of manuscripts and archeological finds to set dates on when the stirrup was used where, but if their basic claim about the importance of the stirrup is true, then there should be much simpler avenues to answering the question. This shows that the stirrup was not as overpowering as is commonly asserted. Important, yes, but important on the scale of chainmail or the rifled barrel, not on the level of the phalanx or the nuclear bomb. Not important enough to explain the transition from armies dominated by infantry to armies dominated by cavalry. If it were, its history would be more apparent. There are any number of important military technologies which can win battles and enable new tactics, but not transform the larger military system that they’re part of, such as the helicopter or the corvus, and the records we have—and don’t have—suggest that the stirrup fits into this category.

This raises two questions. The first, why so many historians have overstated its importance, is relatively simple to answer. For one thing, contemporary prejudices favor explaining large-scale trends as the natural consequence of technological development. More importantly, historians are like anyone else in that they are biased towards simple and compelling explanations for things. The story of the stirrup transforming combat has enough truth to it to lay the foundation for such a narrative. It fits very well from a purely local perspective. In contrast, broad sociological outside-view checks like the one I’m running here seem, if not rare, then at least uncommon.

The more complex question is why Europe transitioned from infantry-based armies to cavalry-based armies, if not for stirrups. The transition came not because Europe’s cavalry was strong, but because its infantry was weak. Infantry can often stand up to cavalry if spearmen stand fast in well-ordered ranks, but if the formation breaks or comes apart then cavalry will win decisively, and maintaining formation while 1500-pound beasts charge at you is not easy. Trained, well-organized soldiers can do this. Mobs of conscript farmers cannot. Nor can hordes of undisciplined warriors, like the barbarian migrants who carved up the Western Roman Empire or who fought for Rome as foederati. The surviving accounts of these battles do not specify whether they used stirrups, but they do make it clear that the armies usually had more in common with Somali militants riding converted pickup trucks than with a U.S. Army battalion. For example Procopius’s telling of the battle of Ad Decimum shows a ridiculous comedy of errors on all sides, where the victorious commander lost control of his vanguard and never managed to deploy his infantry, but won because his opponents were even more disorganized.

After the decline of the Roman legion, the core of Europe had no infantry force that could withstand a cavalry charge for almost a thousand years.¹ When the rising medieval kingdoms eventually managed to organize an effective military system, it was famously based on the mounted knight. Infantry was numerically a greater part of most armies but was far less important to determining the outcome of a battle. This was not a matter of physical technology—the only technology necessary for infantry to stand against cavalry is the long spear, whether that be Alexander’s sarissa or Wellington’s bayoneted musket. Instead it was a consequence of the low social development of the Dark Ages and Early Middle Ages. Between the weak states, the complete dearth of logistical infrastructure, the low urbanization, and the sharp class divisions which precluded high morale from commoners and made any organized peasant force an intolerable threat to the ruling class, no effective infantry force could be raised on feudal soil. It was not until the Late Middle Ages that the rise of mercantile urban power in the Holy Roman Empire and Italy, and royal despotism in France and England, prepared the ground for infantry to grow beyond the limits imposed by feudal society.

This essay is based on my 2019 No One Can Explain The Dominance Of Cavalry, updated after Stephen Morillo explained the dominance of cavalry, and some additional reading on my part.

Follow Ben Landau-Taylor on Twitter: https://twitter.com/benlandautaylor

1. There is arguably a limited exception in the shieldwall’s use in the far north. For example at the Battle of Hastings, the Norman cavalry gave up its usual mobility advantage to charge uphill directly into the English position, whose relatively disciplined shieldwall withstood the attacks at first. Eventually the shieldwall routed after the death of their king.