The Roman Army at War

Despite the prominence of the subject in the public imagination, the general reader has limited access to substantive information on the Roman army. The volumes available in bookstores are usually illustrated uniform and equipment guides, which are full of neat pictures and look great on a coffee table, but are otherwise worthless. Those seeking real information are forced to shell out the money for academic monographs.

Adrian Goldsworthy might be familiar to most people as a serial commentator on those ubiquitous cable “documentaries” about ancient Rome, but his credentials are solid as today’s foremost scholar of Roman military history. I recently finished what is probably his most important work, The Roman Army at War: 100 BC – 200 AD. Goldsworthy’s objective was to write a study of the Roman army as an actual fighting force in the context of its own time; not an anachronistic search for timeless “principles” of strategy and tactics or a social history focused on the daily routine of the soldiers. Thus, he consciously imitates the technique in John Keegan’s The Face of Battle.

The general fascination with the Roman army and the wealth of literature devoted to it makes it all the more surprising that no comprehensive study of its military performance has been attempted this century. Many books have devoted sections to the army’s tactics, organization, and weaponry, but have failed to discuss how the army actually fought. There has been a tendency to shy away from the waging of war. This is the ultimate function of all armies, including the Roman, a statement that is true even for a force only rarely engaged in actual fighting. (2)

Summarizing all the contents of the book would be futile, but here are some of the general points:

(1) The Roman army was much more flexible than it is given credit for. The formal organization of the legions allowed them to adapt to local circumstances, which was all the more important when conquering became garrisoning. For example, the cohort-based structure of the imperial legions permitted them to divide into smaller detachments (vexillations) which was often required to perform the missions of imperial policing and counterinsurgency, tasks that the legions were surprisingly adept at.

(2) Despite their marked disadvantage in military resources, most of Rome’s barbarian enemies opted for decisive battle instead of guerrilla warfare. One possible reason for this was that they recognized that defeating the legions in battle was the only way to slow the Roman juggernaut. However, a more important reason was that their unsophisticated societies could not long sustain an army in the field. Barbarian armies were clumsy, unwieldy things that could only gather for a single, stand-up fight in open terrain. Of course, there were some notable exceptions to this general trend.

And for all the Eastern mystique that surrounded the Parthians, they were almost completely incapable of defeating a well-balanced Roman army. Crassus’ expedition was annihilated only because he neglected to bring sufficient cavalry auxiliaries and foot archers, and his army finally panicked after hours of incessant arrow bombardment.

(3) Roman campaign strategy emphasized the offensive above all else. Even when rebellions broke out unexpectedly, the Romans would aggressively respond with whatever forces were available in the region, even if they were understrength. Sometimes this resulted in disaster, but more often than not, it allowed the Romans to quell uprisings before they burned out of control.

In all types of warfare Roman tactical doctrine was based upon the offensive. The Roman army sought always to bring the conflict to a decisive conclusion as soon as possible by seizing the initiative and dictating the course of the fighting. A decision was reached when the enemy’s will to fight was broken … The Roman emphasis on the offensive in all forms of warfare was another aspect of this attempt to dominate the enemy’s collective willpower and suggested the inevitability of Roman victory. As on the battlefield, the appearance of force was more important than its reality. The appearance of confidence in an army, shown for instance in its willingness to confront overwhelming odds, lowered the enemy’s morale and contributed to to final victory. (114)

(4) Our understanding of the nature of battle in Roman times is distorted by the anachronistic efforts to divine strategic and tactical “principles” from the literary and archaeological record of ancient battles, and by [of course] Hollywood. Many modern scholars are quick to dismiss the skill of most Roman generals on account of the absence of tactical subtlety in their engagements. These criticisms are misplaced, because very few of Rome’s many victories can be attributed to maneuver or stratagem. In fact, the entire Roman military system seemed designed to minimize the role of risky battlefield maneuvers in the pursuit of victory, instead using disciplined heavy infantry to leverage the attritional process.  But this does not mean that Roman generals lacked for talent; rather, Roman generalship manifested itself in ways unique to the times:

The universally harsh judgment of scholars regarding the ability of Roman commanders rests on the fundamentally anachronistic assumption that grand tactics were the general’s most important skill. Few battles involving the Roman army were decided by subtle tactical moves … The technical skill of the Roman general lay not in the sweeping moves of grand tactics, but in paying close attention to the detail of small unit tactics, directing his units, especially the reserves, in response to the changing situation on the battlefield. This role could best be performed by a commander who kept close to the fighting, without becoming personally involved in it. (168-9)

The actual clash of arms bore little resemblance to the extrapolations that Hollywood has produced. At one extreme, the 1960 film Spartacus depicts Roman soldiers as dehumanized automatons, advancing slowly in methodical precision in an inexorable advance that crushes all before it. At the other extreme, the opening battle sequence in Ridley Scott’s Gladiator begins with the cohorts advancing in good order, but then devolves into a chaotic free-for-all with the Romans and Germans intermixed with one another. The reality that Goldsworthy describes resembles neither. Many encounters between infantry were not decisive at all, with the opposing lines frequently separating a short distance from one another to recover from exhaustion before resuming the fight. Victory often came only when a breakthrough was exploited by reserves. The most one-sided battles occurred when the enemy fled as the cohorts approached, resulting in their massacre as the Romans pursued and cut them down.


The book is a dense academic work that presumes the reader already has a basic understanding of Roman society and the Roman army. But its substance is welcome, especially considering the poor quality of the more readily available material. Highly recommended for those interested in the subject.


14 thoughts on “The Roman Army at War

  1. These criticisms are misplaced, because very few of Rome’s many victories can be attributed to maneuver or stratagem. In fact, the entire Roman military system seemed designed to minimize the role of risky battlefield maneuvers in the pursuit of victory, instead using disciplined heavy infantry to leverage the attritional process. But this does not mean that Roman generals lacked for talent; rather, Roman generalship manifested itself in ways unique to the times.

    Fascinating, really. It touches upon a subject I have been thinking about quite a bit recently.

    I would claim that the government of the United States was originally conceived to be StupidProof (TM). The idea was to structure a government that, even if tyrants and idiots came to power, would be unable to destroy the liberty and prosperity of her people. One can debate how well this worked out, but it strikes me as one of the framers’ more pressing concerns.

    Could this approach be taken to military affairs? Is it possible to create a StupidProof military system, one that would continue to function and win battles despite the stupidity, rashness, or fallibility of its generals? It appears that the Romans tried to do just this.

  2. Thinking off the top of my head in Re: T. Greer’s point: a lot, if not most, of Rome’s generals were politicians first who became generals via politics to advance their political career. Based on that asssumption [which may, I agree, be in error], it would behoove the Romans to have a StupidProof military. The key to that, as pertaining to the Romans, would be the Centurians, who learned their skills from the ground up, so to speak. Interesting point Mr. Greer.

  3. The Founders took a great deal of inspiration from the Roman Republic when constructing the U.S. Constitution, particularly the separation of powers. The Senate took elaborate measures to ensure that too much power was not concentrated in a single person. For example, the one-year term of office for every post, and the election of two consuls every year. This extended to the military as well: when both consuls were with the same army, they were expected to reach major decisions through consultation with one another, and command would pass back and forth between them on alternating days. Each legion had more than one legate, and each century would have more than one centurion (though only one would command on the day of battle). Unity of command was not a principle that the Romans valued too highly.

    The Romans did suffer their fair share of idiots. The principle concern of most ambitious Roman officials was to pursue military glory, and as you might expect, this sometimes led to catastrophe. The traditional one-year term of office made policy continuity very difficult (a problem that was somewhat alleviated by the advent of promagistracies). But these drawbacks were balanced by the aggressive spirit that they added to Roman warfare; Rome simply refused to accept defeat. Period.

    I’ve made this point a couple times elsewhere, but what made the legions so effective was that they leveraged Rome’s principle strengths: a large agrarian population, and a warlike society. They were willing to sustain the losses of heavy infantry combat, and because of this, they had escalation dominance over every possible opponent. To this extent, the Roman military was indeed StupidProof, because as long as they could compel battle with the enemy, they were probably going to win. And that’s what counts.

    But I think the most valuable lesson from the Roman Republic is the fear of concentrated power. History proved this to be a valid concern, as the Republic became the Principate. Alas, I fear America might be treading the same path.

  4. Good reply NerveAgent and I agree with you. The only thing I would add re: Legion escalation dominance was the legion trained hard, was better organized and had more discipline than those it fought. This enabled them to consistently defeat foes who outnumbered them. I think a weakness in the system was that many of the politicians seeking military glory were rich enough to raise and pay legions out of their own funds. The legion’s loyalty eventually fell on those who payed them, with the results we’ve seen in the history of Rome.

  5. “The Romans did suffer their fair share of idiots. The principle concern of most ambitious Roman officials was to pursue military glory, and as you might expect, this sometimes led to catastrophe”

    But a smaller catastrophe than an idiot rising to supreme power and finding his level of incompetence as consul. Surviving holding military command in desperate straits weeded out many a patrician idiot before they could stand for the higher offices.

  6. But doesn’t that set us at an impasse? Isn’t it a little contradictory to state that the Roman military system placed behavioral constraints on the strategies and campaigns of its generals and weeded out the good commanders from the bad for higher office? Or did the Romans manage both at the same time?

  7. I think you could say that they managed both at the same time: promotion was based on glory and achievement, which was gained primarily through victories. Keep in mind that the behavioral constraints were maintained primarily by the short term of office and the varied number of officials; any magistrate who held imperium was all-powerful, provided that he was outside Rome itself.

    Interestingly, however, Goldsworthy notes in the book that military defeat rarely resulted in a commander being reprimanded:

    “Rosenstein [a different scholar that Goldsworthy cites] could find no examples of defeated commanders being prosecuted for lack of technical military ability. A general’s career did not suffer as long as had displayed personal virtus. The general showed virtus by displaying physical courage in fighting the battle from close behind the front line, setting an example to and inspiring his men. Even when actually defeated, virtus did not allow the Roman commander to surrender or admit that Rome had lost the war. Rothenstein was surprised that the technical skills of a defeated commander were never questioned at Rome…” (p.165)

    What would truly screw up a career was surrendering or displaying cowardice. This is a reflection of Roman society, which was warlike in the extreme. Along with a disciplined and well-trained army and a large manpower reserve, this is what made Rome such a military superpower.

    I guess it boils down to this: Have the biggest, baddest army in the world, the will to use it, and the resources to replace it. If you have these three things, then any war you fight is StupidProof. I think that sums up Rome’s position pretty well.

  8. “I guess it boils down to this: Have the biggest, baddest army in the world, the will to use it, and the resources to replace it. If you have these three things, then any war you fight is StupidProof.

    But that is strategic StupidProof, an entirely different world from the tactical StupidProof that started this discussion. I am not sure this is a useful way to look at it — we already have a term for it already? What else is meant when we speak of “escalation dominance”?

    But maybe that is the secret in and of itself. The Romans attained tactical superiority over their enemies by making tactics more or less irrelevant. Eliminate grand tactics and there is no need to worry about your tactics failing to achieve the desired ends.

    I am unsure how far up the chain you can take this logic. If eliminating grand tactics makes you more or less StupidProof on the battlefield, does eliminating campaign strategy make you operationally StupidProof? Or, as before, is this just another way of saying “Escalation dominance”?

  9. Another thought, prompted by own ruminations on the subject before you folks could answer my question –

    It seems to me that having escalation dominance is exactly what StupidProof means. The Romans seemed to have this on all levels, IMO.

    A section of the front line is falling? The Roman general orders the reserves to take their spot. Escalation dominance, at the tactical level. A battle was lost? Send in another consul with the reserves. Operational escalation dominance. Our armies have been destroyed? The Senate will levy a new one. Strategic escalation dominance.

    Does that all make sense, or am I off my rocker here?

  10. I think your most recent comment summarizes the matter well, but if we want to distinguish what constitutes “StupidProof” at the tactical level, here’s some clarification of what I mean. This takes us back to the ideas in the initial exchange of comments.

    Roman armies had a great deal of resiliency because they could survive engagements of the highest possible intensity. Escalation dominance. An army of this caliber is wasted when it is used in elaborate maneuvers or stratagems. The best way to use it is by compelling the enemy – often by ravaging his territory – to face it in open battle, where the Romans will surely prove victorious. This is what I meant by “leverag[ing] the attritional process.” This is what made the Roman army StupidProof at the tactical level. It could survive any situation (within reason) that the commander thrust it into.

    And if we think about it for a second, the American armed forces are in a similar position. In my opinion, U.S. dominance at the tactical and operational levels of war is one of our few remaining great national assets. That’s why I’m so aghast when I read about half-baked schemes to convert the army into a constabulary, or equip it with 17-ton vehicles that will magically be able to survive a hit from a 125mm main gun. We lose our escalation dominance if these plans are taken too far.

    But the Roman military system could not function without the will to use it or the manpower to back it up. Sometimes it was defeated, and the losses had to be replaced. Even when victorious, the casualties of heavy infantry combat were often high. But the Romans could replace these losses; their enemies could not.

    Here America isn’t doing so well. We might have the political will to commit our armed forces (not necessarily the political will to pursue victory), but our heavy industry has packed up and moved to China, and our manpower comes from a small segment of the population that is willing to volunteer. The nuclear arsenals of the great powers might make this a moot point, but I doubt that this country could fight on the scale of World War II ever again. As our history for the last 60 years has demonstrated, we do not always have escalation dominance at the strategic level.

    This is a theme that Edward Luttwak touched on in his Grand Strategy of the Byzantine Empire. I’ll quote one of the relevant paragraphs in the book:

    For the Romans, who believed in destroying enemies not wise enough to recognize the advantages of submission, the cutting and thrusting and besieging heavy infantry was the most important arm, because it could best achieve decisive results. By contrast … the Byzantines believed in containing but not destroying their enemies – potentially tomorrow’s allies. Therefore for them the cavalry was the most important arm because its engagements did not have to be decisive, but could instead end with a quick withdrawal, or a cautious pursuit that would leave both sides not too badly damaged. (p. 272-3)

    Byzantium had disciplined heavy infantry, but they could not sustain losses. Thus, maneuver and stratagem were much more important for them than the united empire. The Byzantines did not have escalation dominance, and though they adapted to their circumstances, their military strategy was far less StupidProof than Rome’s. This might be where America is headed.

    Anyway…sorry to go off on a tangent, but I thought I would jot down some ideas related to your own.

    And though I’m sure it’s obvious, I want to say explicitly that I am not an accomplished Roman historian; it’s merely a topic that interests me and that I read about frequently. I would encourage everyone to read about it on their own and come to their own conclusions.

  11. “Keep in mind that the behavioral constraints were maintained primarily by the short term of office”

    Yes. And like the Greeks, the Romans might hold commanders accountable after the fact. Once a proconsul or consul handed over their imperium ( or a praetor command) they might face lawsuit prosecutions for misconduct while in office.

    Abuse of this check by political partisans to “get even” with their rivals by harrassing and humiliating them ( trials were held on public platforms) with nuisance lawsuits helped provoke the Civil War that that ended the Republic

  12. “Abuse of this check by political partisans to ‘get even’ with their rivals by harassing and humiliating thhem. . .” sounds a lot like Senatorial and Congressional Hearings this day and age.

  13. I wouldnt get too depressed by the current state of affairs in the US. Compare our society now to the US at almost any point in the past (note, the actual society, not the Hollywood fantasy portrayal we usually have in our minds) and by pretty much any measure you care to use, we are now more free, wealthy, and safe than any previous generation. We’re certainly a very long way away from seeing the dismembering of the Republic under the weight of rival American armies. On a side note, I would argue that it was actually the fragmentation of power within the Roman Republic, and the corresponding ability of almost any group to bring political change to a standstill, even necessary political reform, that acutally pushed so many politicians into violent/extra-constitutional solutions to the very real political dilemmas of their day. I think the US is in a somewhat better sitaution with a much more flexible, adaptible political system.

    Regarding Roman “Stupid Proofiness,” I think the most significant factor behind Roman expansion and military success was the ability of the State to enlist whole hearted support from the entirety of society (excluding slaves, of course). Pretty much every other state or tribe around the Mediterranean at the time was considerably more fragile, where a narrow elite used the power of the state to extract a majority of their society’s resources for personal consumption. Given this, they could not rely on their societies to support them in significant military efforts. Rome, on the other hand, managed to convince a broad subsection of the population that service of to the State was in their best interests. The most crucial demographics, the aristocrats whose competion was constantly tearing apart other states, competed in fiercely to prove their worth to Rome, not to appropriate a larger share of resources.

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