Roman cavalry

• 1. Introduction

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  Roman cavalry began as three hundred men known as the Celeres, a personal bodyguard riding at the side of Romulus, the city's legendary founder. From that compact escort force, Rome's mounted arm would grow, shrink, transform, and eventually dissolve across more than a thousand years of war. What made these horsemen so central to Roman power? Why did citizen soldiers on horseback eventually vanish entirely from Roman armies? And what replaced them when they were gone? Those are the threads this documentary will follow.

• 2. The Regal Riders

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  Romulus drew his Celeres from the city's three tribes, each contributing a centuria of a hundred men to form the original three hundred. King Tarquinius Priscus, whose conventional dates run from 616 to 578 BC, doubled that number to six hundred. The ancient historian Livy records a further expansion under Servius Tullius that would have brought the total to one thousand eight hundred, but most modern historians consider that figure implausible: it would have created a cavalry force far too large relative to an infantry of eight thousand four hundred men. In peninsular Italy, cavalry typically made up about eight percent of a field army, and the early Republic's actual cavalry confirms this, fielding exactly six hundred men across two legions.

  Membership in this early cavalry was almost certainly a patrician privilege. The aristocracy of early Rome held a purely hereditary claim to rank, and the cavalry was almost certainly their preserve. Some historians, including Alfoldi, have gone so far as to suggest that the Celeres themselves carried out the coup that ended the monarchy. Whatever the truth of that, the patrician monopoly seems to have loosened around 400 BC. By then Rome's cavalry needs were growing faster than its aristocratic families could supply riders, and twelve new centuries of cavalry were formed on the basis of property rather than birth.

• 3. Republican Arms and Armour

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  Polybius, the Greek historian whose Histories were written around the 140s BC, records that early Roman cavalry rode without armour, wearing only a tunic and carrying a light spear alongside an ox-hide shield that deteriorated quickly in action. The picture changed steadily over the following centuries. Coins from the era of the Second Punic War, dated 218-201 BC, show a rider in a variant of a Corinthian helmet with greaves on his legs. A coin struck in 197 BC depicts a cavalryman in a Hellenistic composite cuirass.

  Mail armour entered the picture even earlier than those coins suggest. The Celts had been using mail since around 300 BC, and the Romans may have adopted it from them. By around 150 BC the adoption was complete: Polybius states that First Class cavalrymen were expected to supply themselves with mail cuirasses. The monument that Lucius Aemilius Paullus erected at Delphi to mark his victory at the Battle of Pydna in 168 BC shows Roman horsemen wearing exactly that.

  The question of shields is harder to resolve. Many Roman military tombstones show horsemen with oval shields on the left side of their mounts. But the Ahenobarbus monument of 122 BC and a coin of 136 BC both show cavalrymen riding without shields entirely. Philip Sidnell suggests the answer is simply that equites, who were required to buy their own equipment, chose what suited them. The Roman saddle itself was one of the earliest solid-treed saddles in the Western world, built in a four-horn design used by Rome as early as the first century BC, though it carried no stirrups.

• 4. Pay, Service, and Structure

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  Cavalrymen in the Republican army were paid a drachma per day, which was triple the rate of an infantryman. Their service commitment was also lighter: a maximum of ten campaigning seasons, compared to sixteen for those who fought on foot. Between the ages of seventeen and forty-six, equites were liable for up to a decade of mounted service.

  Each Polybian legion contained three hundred horsemen organised into ten turmae, or squadrons, of thirty men each. The squadron members themselves elected their three officers, called decuriones, meaning leaders of ten men. The first to be chosen led the squadron; the other two served as deputies. No overall commander is attested for a legion's entire cavalry contingent, which is a striking contrast to the highly structured chain of command that governed the legions' infantry. The cavalry of a Polybian legion was armoured and built for the shock charge rather than skirmishing.

• 5. Victories and Defeats

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  At Heraclea in 280 BC, Roman horsemen went toe to toe with the Thessalian cavalry of Pyrrhus, who commanded some of the finest mounted fighters in the Western world at that time. The Roman equites gained the upper hand in what the sources describe as a bitterly contested melee. Only when Pyrrhus deployed his war elephants, which panicked the Roman horses, were the cavalrymen driven back. That detail alone unsettles the common assumption that Roman cavalry was a weak supporting arm.

  Philip Sidnell assembles a longer list of victories. At Telamon the equites beat Gallic horsemen. At Sentinum and Vercellae they defeated Germanic cavalry of the Teutons and Cimbri. At Magnesia they overcame Seleucid cavalry that included fully armoured cataphracts. At Clastidium, Roman cavalry won unaided against superior numbers of both Gallic foot soldiers and horsemen.

  The defeats at Trebia and Cannae, during Hannibal's invasion of Italy from 218 to 216 BC, cut deep and coloured how later historians judged the Roman cavalry. Sidnell's counter-argument is precise: Hannibal held a consistent numerical superiority in horse. A second disadvantage was tactical. Roman equites were trained for the shock melee against enemy cavalry and the flanking attack against infantry; they were not built for the hit-and-run skirmishing that Hannibal's Numidian light cavalry used to exhaust them. When conditions favoured Roman cavalry, as at the Great Plains and at Zama, it performed well even against Carthaginian opponents. At Dertosa it held its own against Carthaginian cavalry despite being outnumbered.

  The losses during those Italian campaigns were staggering. After Cannae, Livy records that the gold rings collected from dead Roman knights filled a pile one modius large, roughly nine litres of rings. In the years 214-203 BC, Rome kept at least twenty-one legions in the field at once, and twenty-five in its peak year, placing enormous pressure on the First Class that supplied the cavalry's officer cadre.

• 6. The Collapse of Citizen Cavalry

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  By the end of the first century BC, citizen cavalry had vanished from the Roman army entirely. The Jugurthine War, Jugurtha's rebellion running from 112 to 105 BC, is the last recorded conflict in which Roman and Italian confederate cavalry played a significant part. Even there, the Romans were heavily dependent on their Numidian allies because Jugurtha's own Numidian horsemen neutralised the advantage that Roman heavy cavalry would normally carry.

  A structural crisis drove this collapse. The Social War of 91-87 BC granted Roman citizenship to Rome's Italian confederates, which abolished the old confederate alae. When the alae disappeared, legionary cavalry shrank to a fraction of a consular army's mounted strength: a two-legion force now fielded about four thousand horsemen in total, but only six hundred of those were Romans, and the citizen contingent may have dropped as low as two hundred and forty.

  By the time of Julius Caesar's Gallic Wars, which ran from 58 to 50 BC, legionary cavalry appears to have vanished altogether. In 58 BC, Caesar needed a cavalry escort for a meeting with the German king Ariovistus. Distrusting his allied Gallic riders, he had them loan their horses to members of his Tenth Legion, which then acquired the nickname equestris, the mounted legion. The episode captures the paradox precisely: Rome's finest infantry could improvise as cavalry, yet Rome no longer maintained a dependable citizen mounted force of its own. The fundamental reason, Sidnell and others suggest, was economics: the native cavalry of Gaul, Spain, Thrace, and Numidia could be hired at lower pay than Roman citizens, and subject territories supplied them in abundance.

• 7. The Imperial Transformation

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  Augustus, when he reorganised the army after the Republic's end, restored a small citizen cavalry force of one hundred and twenty men to each legion, recruited directly from the legionaries. Alongside that token citizen contingent, he built a regular Auxilia corps of non-citizen soldiers drawn from provinces with strong native cavalry traditions. Unlike the foederati allies of the Republic, these Auxilia cavalrymen were paid and trained by the Roman state. A typical cavalryman of the ala earned twenty percent more than a citizen legionary. Arrian describes them as well-equipped and performing well-executed manoeuvres.

  Auxilia cavalry were typically armoured in mail and carried a short lance, javelins, the long spatha sword, and sometimes a bow for specialist horse-archer roles. Their barracks housed horses and riders together in the same building, unlike later cavalry arrangements that stabled animals separately.

  By the third century, Gallienus in 260 created a mobile reserve cavalry corps intended to respond quickly to threats across the empire. Persian cavalry known as the Grivpanvar drove Rome to field growing numbers of heavily armoured cataphractarii and clibinarii by the fourth century, units armed with a large spear, a sword, and a bow. Marcus Aurelius had earlier recruited Sarmatian allied cavalry for service in Britain. By the fourth century Rome leaned heavily on irregular allies drawn from migrating Germanic tribes and the Huns. One constant throughout all these changes: no Roman cavalryman ever rode with stirrups. The device reached Europe only after the fall of the Western Roman Empire, carried by invading tribes whose precise identity remains unknown.