THE AMERICAN All-Volunteer Force is not yet fifty years old. Though created in the late stages of the Cold War, it truly came of age during the post-Cold War period. It now faces its second great shift in strategic priorities, from the “small” wars of the post-Cold War international order towards renewed focus on near-peer competition—a focus which shows no sign of abating during the Biden administration. At the same time, with rising partisan polarization at home creating new concerns about the stability of civil-military relations, now seems a good time to take stock of both the benefits and drawbacks of the All-Volunteer Force.

Anticipating how well the All-Volunteer Force can cope with shifting strategic and domestic conditions is rendered difficult by its relatively short, in historical terms, existence. While it was created in the context of the Cold War, the All-Volunteer Force fortunately never had to rise to a direct near-peer conflict. Perhaps a historical analysis of past professional volunteer armies can serve to fill this gap, offering insight into the benefits and pitfalls of this kind of military recruitment system. Indeed, the professionalization and “volunterization” of the Roman army—often referred to, somewhat misleadingly, as the Marian Reforms—offer some particularly instructive lessons. Arising out of many of the same concerns that motivated the formation of the All-Volunteer Force, the professional Roman army was, like the current United States military, extremely effective and enjoyed a significant qualitative edge on the battlefield on account of its professionalism and discipline. At the same time, the process of professionalization also imposed new and sharp limits on Roman strategic options and eventually destabilized the Roman civil-military relationship, resulting in the army serving as the source of repeated upheavals which both destroyed the Roman Republic and repeatedly plagued the Roman Empire.

Could it happen here? Despite the often-optimistic assessments of the American All-Volunteer Force’s performance, many of these same drawbacks are becoming evident in the U.S. military. Much like modern defenders of the All-Volunteer Force, the Romans seem to have thought that their professional army could be scaled up in an emergency and that the threat to the civilian control could be managed; that neither turned out to be true suggests that in spite of the sometimes-blithe assertions to the contrary, these limitations represent real tradeoffs which are unavoidable with a professional, all-volunteer force. Indeed, the original Gates Commission largely maintained that there were no real tradeoffs to an all-volunteer force, a position that seems optimistic at best given current trends. Consequently, given the mounting evidence for many of the same limitations in the current All-Volunteer Force as in the past Roman one, it is past time for a debate about whether the current recruitment system still fits America’s best domestic and strategic interests.

BOTH ROME and the United States were impelled by similar concerns to shift from conscription to a volunteer force. The first concern, of course, was domestic: the increasingly politically intolerable burden of service for the citizenry had made finding alternatives to continued conscription imperative for politicians. In the United States, the crucial context for the Gates Commission and the subsequent shift to the All-Volunteer Force was draft resistance as a result of the Vietnam War.

The Roman All-Volunteer Force also emerged in the context of increasing popular resistance to the burden of military service in increasingly remote campaigns. Scipio Aemilianus took the first volunteer Roman army with him to Spain in 134 BC as reinforcements for the Numantine War. He had enrolled a force of volunteers apparently because of political resistance to the dilectus (the Roman draft) which had arisen out of the protracted nature of Roman military operations in Spain. The practice of enrolling volunteers, often from among the poorer citizens, rather than drafting farmers, would become permanent in 107 BC when Gaius Marius, in part facing a shortage of eligible draftees—likely from draft-resistance rather than an actual manpower shortage as the Roman conscription system had few mechanisms for true compulsion—enlisted volunteers for the war against Jugurtha, a Numidian prince in North Africa.

There was a broader economic dimension to political resistance to the draft in both cases. While the Gates Commission report avoids dwelling on the anti-war movement (though for all involved this was the well-understood background to the report), it does give considerable prominence to the economic cost of service. Noting that “conscription is a tax” because the low wages of compelled service meant that “draftees and draft-induced enlistees [were] bearing a tax burden over three times that of comparable citizens,” the Gates Commission recommended that the All-Volunteer Force, while costing more to the federal budget, would represent an overall reduction on the economic burden of service on the citizenry.

This line of thinking, that conscription meant that the economic burden of service fell unfairly, would have been perfectly at home in the Roman Republic of the second century BC as the foundations of the later Roman professional army were beginning to form. In 133 BC, just one year after Scipio Aemilianus’ successful experiment with enlisting an all-volunteer army, Tiberius Gracchus, a tribune of the plebs, proposed a sweeping land reform package. Tiberius’ reforms were motivated by an apparent manpower shortage. This shortage was caused, the Romans thought, by the fact that the Italian peasantry had been crushed by the burden of repeated military service. Long campaigns had led them to lose their farms which, because there was a wealth requirement to serve as Roman soldiers needed to supply their own equipment, led in turn to them being both poor and ineligible for the draft. Modern scholars still debate the degree to which this manpower shortage was real, as the Roman census was self-reported such that draft resistance might show up as demographic or economic decline. Nevertheless, it was clearly a hot-button issue at the time: Tiberius’ reform package was passed even over the near-united opposition of the Senate, whereupon the senators murdered him for his troubles, inaugurating a spiral of violence which would eventually culminate in the collapse of the Republic itself.

The second part of this concern over the burden of military service and resistance to it was the need to adapt to a changing security situation more focused on holding on to what had been gained, what we may call “frontier maintenance,” and less focused on expansion or wars with peer competitors. In the Roman case, the Roman Republic’s system of conscription in the third and second centuries served it extraordinarily well, enabling Rome to out-mobilize its competitors at a relatively low cost to the limited Roman treasury (though with a somewhat greater cost to Roman citizens, as many costs were devolved down to private individuals). But, as the resistance to the dilectus for both Spain in 133 BC and North Africa in 107 BC showed, the Romans were reluctant to support continued conscription for increasingly long, distant, and unprofitable wars. Earlier wars against Pyrrhus of Epirus (280–275 BC) and Carthage (264–241 BC, 218–201 BC) had demanded tremendous sacrifice, but they had been local wars with peer competitors that posed a clear potential danger to the Roman state. Later wars against Macedon (200–196 BC, 172–168 BC, 150–148 BC) and the Seleucid Empire (192–188 BC) had been less clearly tethered to immediate Roman security concerns, but had at least been profitable, giving soldiers and senators alike the opportunity to loot the vast wealth of the eastern Mediterranean.

But the long wars in Spain and North Africa, waged merely to hold on to and consolidate earlier territorial gains outside of Italy, were both only loosely tethered to Roman security concerns and offered fewer (though by no means none) opportunities for soldiers to enrich themselves. At the same time, the Romans were unwilling to give up the vast empire they had acquired, the tribute of which was by that time already sufficient for most taxes in Italy to have been discontinued. Given that set of incentives, which would only intensify as Rome turned almost fully from conquest to holding the frontier under Augustus (who was, in turn, responsible for the true professionalization of the legions, turning them into standing units of long-service professionals), the shift to an all-volunteer professional force seems almost overdetermined.

Interestingly, the Romans were not the only empire at this time which, when faced with a security profile that had shifted from the conquest of peer competitors to the consolidation and maintenance of gains, moved from a mass conscript army to a more permanent, long-service force. As the Han Dynasty (202 BC to 221 AD) emerged as the final winner of the Warring States period (and the brief rule of the Qin Dynasty, 221–206 BC), it steadily moved away from universal conscription in order to more effectively guard its frontiers, particularly on the steppe. While the Han initially had a military system requiring all males between the ages of twenty-three and fifty-six to perform two years of military service (one in their home province, one abroad), early in the first century AD, this system was discontinued in favor of a fully professional military deployed primarily to the frontiers.

The final transformation of Rome’s armies into a professional all-volunteer force came during a period of shifting Roman security demands as well. With the Battle of Actium (31 BC), Octavian, soon to be Augustus, had removed both the last near-peer state on the Mediterranean (Cleopatra’s Ptolemaic kingdom in Egypt) and the threat of other Roman peer competitors (in the form of rival Roman commanders) for the foreseeable future. Consequently, when Augustus regularized the army’s terms of service, he also reoriented by the end of his reign the Roman army’s mission from one of expansion to border protection. The legions were redeployed along the whole frontier, rather than concentrated for offensive operations, and Augustus himself left instructions to his successors that they should focus on holding the empire rather than expanding it. Further major campaigns of imperial expansion under Augustus would be infrequent and generally of smaller scale than those that came before.

The American shift to an all-volunteer force in the last decades of the Cold War is thus hardly a sui generis event. Rather, the United States joins the company of a number of great powers which, having acquired a position of dominance through mass conscript armies, then sought to maintain that position with a professional army. In that context, the experience of Rome is quite informative, given that it at least started the process as a republic. And it turns out, there are already quite a few signs that the processes which began to work upon the Roman army once it started to professionalize are now already working upon the American All-Volunteer Force, with potentially perilous results.

ONE OF the assurances of the Gates Commission was that the adoption of the All-Volunteer Force would not necessarily restrict the ability of the United States to reengage conscription in the event that some future conflict required it. Consequently, the ability of the United States to respond to the need to raise very large armies in the event of renewed large-scale conventional war with a peer competitor would not be reduced. The Romans seem to have thought the same thing. Roman commanders were certainly able to raise large armies relatively quickly in Italy during the Roman civil wars of the first century BC, with the ethic of universal citizen military service still a quite recent memory. As late as 6 AD, the Romans were able to rapidly raise fresh forces in response to a revolt in Illyria, supplementing the ten regular legions brought into the province with 10,000 Italian veterans (the equivalent of two more legions) and a “large number of volunteers.”

But that strategic flexibility does not seem to have lasted for very long. It is striking that only a small portion of the total force that responded to the Illyrian crisis was made of new units. Despite the war in Illyria continuing for three years, the fighting was done primarily by legions redirected from the Rhine and Danube frontiers. That meant calling off Tiberius’ planned campaign against the Marcomanni (a Germanic people) because those legions had to be redirected to Illyria, a move which in turn left the Roman presence in Germany thin on the ground, contributing to the isolation and destruction of the three Roman legions left behind at the Battle of Teutoberg Forest in 9 AD. The three lost legions were not replaced with fresh formations either, with existing legions instead being shifted from Spain and Pannonia to cover the gap, and Augustus responding by halting Roman expansion and, as noted above, advising his successors to do the same. The strain on the remaining legions is evident when in 14 AD the legions on the Rhine mutinied, citing among other injuries that their tours of duty had been extended well beyond the regulation twenty years, in an apparent ancient version of stop-loss.

In the decades that followed, the Roman army increasingly calcified as a professional force. Emperors sometimes added a legion or failed to replace a lost legion, but the overall strength of the army generally stayed just below thirty legions with a matching number of non-citizen auxiliaries. Not only did the size of the Roman army become resistant to change, so did its fighting style. While the Roman conscript legions of the Middle and Late Republic had been quick to innovate or adapt foreign weapons, the legions on the Column of Trajan (110 AD) and the Column of Marcus Aurelius (193 AD) had substantively the same organization, equipment, and tactics as Augustus’ legions fully two centuries earlier (although some degree of tactical flexibility was kept through the use of non-Roman auxiliaries using their own fighting styles).

It is not too hard to find the sources for this calcification. When it came to force structure, the vast cost of keeping a professional army in the field continuously was a perpetual burden to the Roman treasury, probably consuming around half of all Roman state revenues. Such a crushing burden left little room for organizational innovation. Where the Roman Republic, with its conscription-based system, had often been able to do more with less compared to its rivals, the Roman Empire using a long-service professional model was forced to outlay tremendous sums to maintain dominance. At the same time, the permanence of the legions themselves may have served to encourage the relative stagnation in both tactics and equipment.

The emergence of a permanent, standing Roman All-Volunteer Force had significant strategic impacts too. While the Romans had never been very averse to war and Roman popular resistance to further military activity during the Republic was generally limited, emperors possessed of a “paid for” standing military had few incentives not to use it. The strategic value of Claudius’ invasion of Britain, launched to provide the emperor the political fig-leaf of military success, was questioned even in antiquity. Similarly, Dacia, invaded by Trajan in a war of choice in 101 AD and finally absorbed as a Roman province in 106 AD, was the first province to be relinquished by the Romans (practically in 253 AD, formally by 275 AD) because its exposed position rendered it untenable.

So long as Rome’s security threats remained relatively the same, facing non-state peoples over the Rhine and Danube (and after 43 AD, in Britain) along with a relatively decentralized and less aggressive peer competitor in the form of Parthia, the calcified Roman military system was able to cope reasonably well. But by the third century, that threat profile had changed substantially, with the peoples living over the Rhine and Danube organized into increasingly larger and more dangerous confederations and with the far more centralized and aggressive Sassanid Empire replacing the Parthians as Rome’s peer competitor to the east.

By that point, however, the Roman army had largely ossified as an institution. On the frontier, the legions were progressively broken up into ad hoc detachments called vexilationes, as the empire tried to meet a changing security situation with the calcified, professional military it had rather than raising fresh formations it could not afford in no small part due to the heavy cost of maintaining the legions themselves.

The notion that, in an emergency, the Romans might return to their old ways was exposed as an illusion in 238 AD when the Roman Senate attempted to hold a traditional dilectus in Italy in response to an outbreak of civil war. The formations raised that way were little more than a self-armed mob, unable to even contain the small detachment of praetorians in the city, much less handle a field engagement against a true army. Instead, the Senate was only rescued by the surprisingly stubborn civilian defense of Aquileia and the logistical incompetence of Maximinus in his effort to march on Rome. In stark contrast to the days of the republic, when the Romans could raise significant armies to recover from defeats even with enemy forces operating in Italy, by the third century AD the Romans were apparently simply incapable of rapidly raising new domestic forces in an emergency. Subsequent reorganization by Diocletian and Constantine would resolve some of the operational mobility issues of the old system, but not the crushing budgetary costs nor the inability of the system to be scaled up. These limitations left Roman commanders increasingly reliant on foederati, non-Roman troops serving under their own leaders, to make up the difference, especially in the Western Roman Empire, which in turn resulted in the long-term collapse of central authority.

It is not hard to see the warning signs that a similar process of degeneration is in its early stages with the American All-Volunteer Force. Despite the Gates Commission’s pollyannish insistence that an all-volunteer force could be expanded during periods of greater need, the opposite has proved to be true. Faced with conflicts connected to the Global War on Terror in Afghanistan and Iraq, the United States found itself stretching its limited forces thin, unable or unwilling to either expand the military or to curtail strategic objectives. Notably, these were conflicts, while long-running and large compared to American military activity in the decade prior, were quite small compared to what would be required in the event of a peer competitor conflict.

At the same time, the All-Volunteer Force has proved resistant to expansion in times of increased security need, it has also proved difficult to shrink its significant cost during periods of relative peace. As with the Roman All-Volunteer Force, the formation of a professional military has also created natural political interests opposed to measures that would have enabled even relatively ineffective spending to be cut down in peaceful years. Even in the relatively secure years of the 1990s, U.S. military spending never passed below 3 percent of GDP and declined only slightly in real dollar figures.

Yet despite the historically massive expenditure on a “peace time” military (inasmuch as the United States’ continuous global deployments may be considered “peace time”), and despite the fact that U.S. military spending remains substantially greater than any possible competitor, American policymakers increasingly face hard tradeoffs where even record budgets cannot stretch. In particular, American policymakers face severe tradeoffs between investing in present capabilities, or future capacity, where the large standing All-Volunteer Force essentially commits the United States to a focus on present capabilities even when the specter of rising competition with peer competitors like China might suggest for a capacity-focused approach.

The American All-Volunteer Force has not yet had two centuries for its doctrine to stagnate in the way that the Roman army did. Nevertheless, the all-too-eager reorientation towards large-scale combat operations (LSCO) suggests increasing inflexibility in how at least part of the United States military understands its mission. That the United States military has often had to relearn how to operate outside of LSCO is a point well-made by Nadia Schadlow in War and the Art of Governance. But a lack of institutional memory is rather a different thing from the determination that the military simply ought not to be asked to wage certain kinds of wars, documented by David Fitzgerald in Learning to Forget for example, and all but advocated by Daniel Bolger in Why We Lost. It is too early to tell if the shift back to LSCO and peer competition advocated in the 2017 National Security Strategy and seemingly also endorsed by the new Biden administration is a sign of a determination by the military establishment to become more flexible in confronting multiple kinds of missions or if it is merely a retreat back to the familiar comforts of planning for LSCO and so a sign of further doctrinal calcification.

THE GATES Commission also insisted that “the long-established institutional framework, firm public attitudes, and the similarity of future forces with or without conscription will help prevent separation between the armed forces and society.” Again, a sober look at the Roman example might have tempered such optimistic assumptions. The Roman experience offers stark warnings about the long-term impact of an all-volunteer military on the civil-military relationship. The collapse of the Roman Republic was complex, and ought not be simplified to a single cause. But the failure of the civil-military relationship as a consequence of the process of professionalization in the Roman army was a clear accelerant in the crisis.

Rome was not lacking in “long-established institutional frameworks.” By the time the Roman army began to professionalize and shift slowly towards the all-volunteer forces of the first century BC, the Romans had held to a tradition of universal male military service among the landholding classes since the foundation of the republic in 509 BC, although the exact form and structure of the early Roman army is beyond confident reconstruction.

Prior to the professionalization of Rome’s armies, there was a strong connection between the citizen body that voted for war and the soldiers who waged that war. The civil-military relationship in Rome was, as in modern democracies with conscription, rooted in the effective identity between the citizenry as a political body and the army; all of the same citizens who fought also voted and vice versa. Votes on war and peace were always held in the most formal of Rome’s voting assemblies, the Centuriate Assembly (comitia centuriata), which was itself organized by the same census class distinctions which in turn determined how citizens would serve in the army—citizens voted for war arranged exactly as they would have to fight in that war. Where the interests of the Roman people diverged from those of the Roman oligarchy, that very equivalence between soldiers and citizens could enable the citizenry to extract concessions from the elite by refusing to serve, as happened repeatedly with successions of the plebs during the struggle of the orders (494–287 BC).

Despite this long history and undoubtedly “firm public attitudes” about the sanctity of the republic, the professionalization of the Roman army in the Late Republic nevertheless had the effect of misaligning the interests and incentives of the Roman soldiery from those of either the Roman people or the Roman Senate, which, although it lacked many formal powers, was in practice the core Roman civil governing institution. This misalignment occurred against the backdrop of elevated, though not unprecedented, political tensions within the Roman Republic, concerning the extension of citizenship to Rome’s Italian allies and arguments over land reform. Much as in the United States today, many of the tense political debates of the time revolved around the perception that Rome’s rising wealth had enriched a select few while leaving many common Romans behind or even worse off.

Previous political tensions of this sort had been to a degree mediated by the fact that the citizen body and the army were so nearly identical, enabling the citizenry to extract concessions from the elite without violence by refusal to serve. That professionalization decoupled this relationship was not an unintended consequence, but (as noted above) the intended goal in order to overcome civilian resistance to conscription without having to trim Rome’s strategic ambitions (or the ambitions of Roman politicians for whom military success was a prerequisite to greater political stature). Nevertheless, it was perhaps only a matter of time before politician-generals whose political agendas were hopelessly bogged down in the political gridlock recognized the potential for using their veterans or their armies to push things through. And so, Gaius Marius was prepared, in 100 BC and later again in 86 BC, to use the veterans of his campaigns to intimidate voters and achieve with violence what he had not managed by persuasion. It was a small step until Sulla could turn his army against Rome, armed with promises of loot to be gained in the east which the troops, veterans of his campaigns in the Social Wars, might not expect if his opponents remained in power. These were examples subsequent Roman commanders would follow, exploiting the disconnect between the incentives of the soldiery and the citizenry to turn the one on the other in the pursuit of power.

Augustus was subsequently able to realign the incentives of the Roman state and soldier, but only by combining them in himself and cutting out the people altogether. Nevertheless, the distinctive culture of the army often made it difficult for “civilian” emperors to control it. The emperor Nerva was effectively compelled to select Trajan, a military man, as his heir, to satisfy the army. Septimius Severus’ dying advice to his sons, to “Be harmonious with each other, enrich the soldiers and scorn all others” spoke to the degree that the demands of the army had eclipsed the needs of the people or the state. In the event, the last emperor of Septimius’ dynasty, Alexander Severus, was assassinated by his soldiers for prudently avoiding a war which would have been costly to the treasury but enriching to the soldiery. The soldiers replaced him with an officer, Maximinus Thrax, who represented the soldiery well but whose political incompetence plunged Rome into the crisis of the third century after just a three-year reign.

Obviously, the American civil-military relationship is not in such dire straits as this, but there are more than a few troubling signs that the beginnings of the processes which eventually unmoored the Roman civil-military relationship are now underway. The recent confirmation of former general Lloyd Austin as the secretary of defense, the second former general in four years to be appointed to the post, has raised renewed concerns about civilian control of the military. While Austin has pledged to uphold civilian control of the military, it seems that the norm against appointing former members of the armed services to the position has been eviscerated by Donald Trump and Joe Biden. 

Equally concerning is the implication that presidents looking to signal their tough competence on military matters have now found that the way to do it is to appoint a former member of the military. That political strategy suggests that there is an emerging public perception that on matters of national strategy (matters that Carl von Clausewitz, in his trinity, sensibly leaves under the purview of politics and the state) former officers have a unique competence not reproducible from the civilian realm. It is a viewpoint increasingly held by members of the All-Volunteer Force themselves, an apparent consequence of the increasing isolation of volunteer personnel from the society they serve. That public perception is, in the long run, likely to be more dangerous than any individual appointment of a patriotic, public-spirited former general. After all, it is a short leap from the assumption that former officers have that unique competence to the conclusion that only such individuals ought to be trusted with such weighty decisions. Nevertheless, it remains true, as Georges Clemenceau quipped, “la guerre, C’est une chose trop grave pour la confier à des militaires” (war is too serious a matter to entrust to military men). There is a real, albeit distant, risk of national strategy becoming something decided on by military, to be carried out by the military. Past states which collapsed the corners of the trinity this way fared poorly.

The more immediate risk, however, is that created by the confluence of a widening civil-military gap when combined with increasingly tense and polarized partisan politics. The statement, issued in the Washington Post on January 3, by every living former defense secretary declaring that the military had no role in an election might well be taken as reassuring, but the very necessity of such a letter spoke to the real concerns among the defense establishment that an effort might be underway to use the military in exactly this way. That this concern, expressed before the January 6 insurrection, was not entirely unfounded seems borne out by subsequent events. Initial reporting has suggested that roughly 20 percent of individuals arrested for actions connected to the January 6 insurrection were current or former U.S. military personnel, more than double the rate in the general population. At least one of the capitol insurrectionists appears to have been a retired lieutenant colonel in the Air Force. And Michael Flynn, a retired lieutenant general and former national security advisor to former President Donald Trump, even suggested that the president might use the army in exactly the way Sulla did, to rerun an election that had produced an “unacceptable” result. Fortunately, his suggestion that this could be done went unheeded by either the former president or the military. Nevertheless, the Roman example strongly suggests that heightened partisan polarization increases the risks that an all-volunteer force poses to civilian government. Given that the United States’ current period of high negative polarization shows no signs of ebbing, this ought to be concerning indeed.

THE COMPARISON of all-volunteer forces over such chronological distance suggests two things. First, there were indeed serious historical reasons to doubt many of the blithe assertions made by the Gates Commission, or subsequent supporters of the All-Volunteer Force, that it need not lead to a less flexible military, nor foster a potentially dangerous civil-military gap. Already there is substantial evidence that these assurances, while perhaps honestly offered, have not held true.

At the same time, the presence of these very drawbacks in other all-volunteer forces like the Roman army also indicates that many of these drawbacks are congenital, rather than merely easily solved artefacts of the particular current implementation of the American All-Volunteer Force. This is not to say there are not counter-balancing advantages, both domestic and strategic, to the All-Volunteer Force. But it does suggest that these dangers are the essential and probably unavoidable tradeoffs of gaining the advantages of a professional all-volunteer force.

On the one hand, the shift to a strategy oriented towards peer competition is likely to require an emphasis on future capacity over present capabilities—a set of strategic priorities poorly served by the demands of maintaining a large, all-volunteer force in-being even during periods of relative peace. The experience in Iraq after 2003 has already demonstrated how difficult it can be to scale-up a professional, all-volunteer force to meet new security needs. On the other hand, the shift towards increasingly intense domestic partisan polarization heightens the danger the All-Volunteer Force poses to the country itself. In such situations, an all-volunteer force is the national equivalent to keeping a loaded gun in the house of a country going through the political equivalent of a depressive episode. Against these concerns, of course, must be balanced the advantages in operational capabilities and strategic options that the All-Volunteer Force provides. The All-Volunteer Force is like a sharp, double-edged Roman sword. We can only be in a position to decide if the sharpness of the back edge is worth the sharpness of the front edge by acknowledging that both edges are dangerous.

Bret Devereaux is a visiting lecturer at the Department of History of the University of North Carolina at Chapel Hill.

Image: Wikimedia Commons.