While reading Charles Oman's "A History of the Art of War in the Middle Ages" it occurred to me that horses and a kind of knight were always available to the Roman Empire, and nevertheless the legions were mostly composed of infantry. He even says that the highest ratio that horseback soldiers had compared to infantry at any given time was 1/6, and that normally it didn't surpass 1/12. After this, the author proceeds to highlight that cavalry was a major advance in the art of war after the Roman Empire, and that mounted knights always won battles against infantry. This created my doubt: if horsemen were so superior in battle why were the legions composed mostly of infantry?

Something that Oman says is that after the Roman Empire there were mounted archers instead of mounted infantry. Was that the 'major advancement' in military technique?

As the book was written in 1885 maybe some of the information may be outdated and today we may have a different vision. If so, what did we discover in this matter since 1885?

  • You might find this helpful: history.stackexchange.com/questions/838/… Aug 19, 2016 at 14:36
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    Stirrup. Tactics. Supply. But mostly the stirrup.
    – MCW
    Aug 19, 2016 at 14:39
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    "If horsemen were so superior...." - the author asserts that Medieval horsemen were superior, and you're countering with "why didn't the Romans have Medieval horsemen...." - I think the answer may be found in the high cost of time machines.
    – MCW
    Aug 24, 2016 at 13:44

4 Answers 4


Two parts here:

1) Why didn't the Romans have cavalry?

They did, at least early on. However, after about 107 BC they reorganized their military, and appear to have decided that other societies produced better cavalry cheaper, so they'd just use theirs*.

The problem here, as I understand Oman's logic, was that as Cavalry became more and more dominant, this made the Romans more and more dependent on foreigners for their military. Given the tradition of generals installing themselves as Emperor, it was only a matter of time before foreign generals started running things.

2) Was Oman right back in the 19th century? Was this really that big of a deal?

This is actually a matter of some debate. There are some who say yes, and further it was really the stirrup that caused it all. There are others who say it wasn't, and the real problem was a demographic crash in the western Roman Empire, which could have been caused by economics, or plagues, or climate change, or all kinds of other things.

* - I believe the theory is that it is far easier for a pastoral society (eg: Berbers, Goths, Huns) to produce trained cavalry, as their children grow up on horseback and they are tending and keeping lots of horses as it is. A farming culture is much better at producing infantry.

  • Just as a personal note, I'm kind of a fan of Oman's theory for how nicely it ties everything up (from the fall of the Roman Empire, to the European Feudal System, to the repeated conquests of China...). However, it doesn't seem to be popular today. There are probably good reasons for that.
    – T.E.D.
    Aug 19, 2016 at 16:07
  • Romans had an "Equestrian Order" so horses were highly valued and prized for them unlike say for their Greek "ancestors." The difference lay in the use of Horses for logistics...which was absolutely critical for supplying the masssed heavy infantry of the Roman Legions. And of course this excluded carrying the Roman Legionaire who was expected and indeed did march on foot...plus his gear. That made the Horse's job a LOT easier. Carthage of course used their Navy which if Rome and Carthage had ever gotten along would have been a truly formidable combination. Instead... Aug 19, 2016 at 17:52
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    @user14394 - I believe my first link was specifically addressing the Equites, and what happened to them after 107 BC.
    – T.E.D.
    Aug 19, 2016 at 17:57
  • @T.E.D.: A slightly better statement might be that "the Romans always had cavalry (at least when it mattered) - but that after 107 BC it was universally auxiliary". For instance Caesar had German Auxiliary cavalry in Gaul; which once mounted on the larger Gaulish horses terrified the Gallic cavalry. Aug 20, 2016 at 18:52
  • @T.E.D.: I believe that the falling popularity of Oman's thesis is due to political correctness. People don't want to believe that one knight on a horse and with "real" armor was worth 5-10 "peasant" infantrymen. On level ground and in good weather of course. (It rained shortly before the battles of Crecy, Poitiers, and Agincourt, putting the cavalry at a disadvantage.)
    – Tom Au
    Aug 21, 2016 at 2:12

Soldiers mounted on horses were an advantage when horse and rider could fight as a unit. This occurred after the invention of the stirrup, up to the time of rifles.

Before the stirrup, a cavalryman had to manage his horse and weapon separately. That gave the advantage to "infantry," at least the Roman kind. The stirrup was not introduced into European warfare until at least the fifth century CE (at the very end of the Roman empire), possibly later. Basically, the Roman empire did not live to see the benefits.

The addition of a stirrup basically fused horse and rider. A horseman could charge infantry at 4-5 times the speed of the footmen, and the horse also weighed 5-10 times as much as a man. It's no exaggeration to say that on level ground in good weather, a horse and rider working as a "team" had 5-10 times the value of an infantryman, when both were armed with spears, lances, and swords. This gave cavalry the advantage from 400 or 500 CE to at least 1500 CE.

The advent of the musket reduced the horeseman's advantage (in much the same was as the long bow), but it wasn't until the introduction of long-ranged rifles in the 19th century that the advantage of the horseman was fully overcome. It was much harder for a horseman to manage a rifle and reins simultaneously, than a blade weapon and reins, so horse and rider effectively became "two" (different) units again during the rifle era.

On the other hand, horsemen could use blade weapons during the era of the musket (1500-1800), for which "killing distance" was only 50 yards, at which range the musketeer could fire only one shot. It was the longer-ranged, faster-loading rifle that made it impossible for a horseman to compete on equal terms with infantry.

  • In the 19th Century, the rifle's range was less a factor than the repeating rifle's higher rate of fire. The potential for each infantryman to bring down two or three cavalrymen during a charge definitely shifted the balance of power.
    – Steve Bird
    Aug 19, 2016 at 18:31
  • @SteveBird:Basically, between "range" and "repeating," a rifleman could get off "several" shots during a cavalry charge, not just one, as in the case of muskets. And I did say "faster-loading."
    – Tom Au
    Aug 19, 2016 at 20:13
  • If the infantryman was armed with a spear, I don't think the horseman would still be worth 5-10 times more... Aug 19, 2016 at 21:49
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    @user14394: Your talking about 19th century cavalry when the fighters had to use firearms to compete effectively with infantry. I was talking about medieval cavalry when a spearman advancing at 10-12 miles an hour, and carrying a lance at an elevation had a massive advantage over a spear-carrying foot soldier advancing at 2-3 miles per hour. And after firearms arrived, :"elevation" was a disadvantage, before that, an advantage.
    – Tom Au
    Aug 20, 2016 at 1:09
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    @user14394: Your take on medieval (sp!) cavalry being "mostly ceremonial" is completely off track. Cavalry featured prominently in just about every major encounter, and dominated battlefield tactics from antique times well into the 19th century.
    – DevSolar
    Aug 30, 2016 at 14:01

Mounted soldiers date back at least to the Neo-Assyrian Empire, and were a significant part of Persian armies, who emphasized heavily armored horsemen (including armor for the horse); the general term that gets used for these pre-medieval heavy cavalry is cataphract.

It's true that the Romans didn't emphasize cavalry much, but they did end up deploying some heavy cavalry units in the east, against the Parthian and (later) Sassanid Persians; the Byzantines continued this practice in their wars against the Sassanids.

The idea of stirrups (which showed up long after armored, lance-using cavalry appeared in the Levant) as a critical invention is generally now seen as an exaggeration. (Stirrups are better, certainly, but mounted warriors were able to brace themselves and deliver powerful attacks using well-designed saddles prior to the appearance of stirrups.) See here for a list of references on the stirrups issue.

As for mounted archery: it certainly was a significant advance -- groups like the Mongols and Turks used it very effectively, and tended to defeat European knights when they fought against them -- but again it's something pre-dating the Romans, as Luis Henrique noted in his answer. There are clear records of it from the Neo-Assyrian Empire.

If you want a nice illustration of when these things were actually in use, there's the Battle of Carrhae (53 BC), where a Roman army was wiped out by the Parthians using a combination of cataphracts and horse archers. (But note that the Romans also won battles against the Parthians and their successors the Sassanids, so the "cavalry always defeats infantry" argument is clearly false.)


While reading Charles Oman's "A History of the Art of War in the Middle Ages" it occurred to me that horses and a kind of knight were always available to the Roman Empire,

Horses were, knights not so much, though the Romans had an "Equestrian Class", which were "knights", if not militarily, at least socially. As Tom Au says, the stirrup was the fundamental inovation that made heavy cavalry possible. Without a stirrup, riders can be unseated, not just by the efforts of enemy infantrymen, but by their own push when charging: if their weapon was a lance, the impact of it upon the enemy would backlash against them, with disasterous consequences. So, before the stirrup, cavalry was necessarily light cavalry, either armed with swords or bows. Cavalry with swords was useful for persecution, preventing the enemy from regrouping, and could also outflank the enemy, attack from behind, and disorganise their lines completely. Cavalry with bows, or mounted archers, were excellent skirmishers, that could harrass the enemy from distance, relying on speed and mobility. But neither could actually charge, in the sense we think of cavalry charges; the charging weapons in ancient times were chariots, which are far less manoeverable than mounted horses.

Medieval heavy cavalry could charge against infantry, because stirrups made unseating knights much more difficult. And its impact had high momentum: the total mass of horse and knight, multiplied by the speed of the horse. Being trampled by that was extremely lethal; only a very skilled infantry, heavily armoured, and armed with pikes could sustain a direct cavalry charge.

After this, the author proceeds to highlight that cavalry was a major advance in the art of war after the Roman Empire, and that mounted knights always won battles against infantry. This created my doubt: if horsemen were so superior in battle why were the legions composed mostly of infantry?

Oman is basically right about the power of knights; of course they didn't win "always"; Agincourt is an example of them being soundly defeated. But Agincourt is one exception; several different and unusual factors made the English victory there possible: the narrowness of the terrain, the muddy soil, poor command, the disorganised structure of the French force. Those, combined with correct tactics by the English (the ample use of longbows by bowmen protected by spikes), defeated the French cavalry). Also, heavy cavalry is not a good option in hilly terrain - which is the reason that plebeian Switzerland could secure its independence against foreign nobility. But, "normally", cavalry could break the lines of infantry, yes.

Tom Au brings up the interesting notion of rider and horse becoming a single unit, due to the stirrup. Similarly, infantry was not an actual unit at that time. Bowmen and pikemen were different weapons at war; the former could shoot, but only the later could engage directly with the enemy. And that intrinsic division was to be only healed much later, with the invention of the bayonet, that allowed footsoldiers to charge and shoot simultaneously (and, in this respect, Agincourt is also kind of a premonition: due to the disarray within the French army, bowmen could, at the end of the battle, take swords and finish the defeated Frenchmen; but such fusion between the two parts of infantry was, at that time, only possible in extraordinary circumstances).

Something that Oman says is that after the Roman Empire there were mounted archers instead of mounted infantry. Was that the 'major advancement' in military technique?

Mounted archers are much older; the Romans faced them when they fought the Partians. And Huns and other nomadic people also used this kind of military unit. The specificity of mediaeval cavalry was the use of brute force and lances, to turn knight-and-horse into an almost unstoppable impact weapon, that sought direct combact instead of diverting from it.

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    The cataphract -- heavily armored cavalry using lances -- predates the stirrup by a comfortable margin. While I agree with Tom Au that the stirrup allowed horse and rider to cooperate on a completely new level, I find the assertions made in your first paragraph to be rather excessive.
    – DevSolar
    Aug 30, 2016 at 14:12

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