This is the most important one, but perhaps a bit less complicated than cohorts: the notion that Marius began the process of taking volunteers and proletarii at that and thus “professionalized” the Roman army. As with the equipment, this is at least something our sources do say … more or less.

Sallust reports that Marius, “after he saw that the spirits of the plebs were aroused, he swiftly loaded ships with supplies, pay, weapons and other requirements; with them he ordered Aulus Manlius, his legate, to set out. Meanwhile himself he enrolled soldiers, not according to the mos maiorum [‘the customs of the ancestors’] from the census classes, but making use of whoever wished to go, mostly the capite censi [‘those counted by heads’ = the propertyless poor or proletarii]” (Sall. Iug. 86.1-2, trans mine). Plutarch repeats this report, that Marius violated custom by enrolling men who didn’t meet the property qualification for military service (Plut. Mar. 9.1).

There are a few oddities here to start, though. First, Sallust quickly notes that this resulted in Marius having an army rather larger than what the Senate had actually authorized (Sall. Iug. 86.4) and that’s actually quite a neat detail that may explain part of what’s going on here because this has, in a way, happened before. In 134, Scipio Aemilianus was elected consul for the second time (illegally, again) with a mandate to end the frustrating Roman war against the Celtiberian stronghold of Numantia in Spain. The Senate, however, denied Scipio authorization to raise fresh troops, to which Scipio responded by enlisting some 4,000 volunteers to replenish his legion; Appian says this was done with the consent of the Senate, but Plutarch’s brief note on it sure implies Scipio Aemilianus is end-running around Senatorial efforts to stifle him (App. Hisp. 84; Plut. Mor. 201A-B). And this too was hardly the first time for this sort of end-run; Scipio Africanus (what is it with Scipiones!?) back in 205 agitated for his invasion of Africa to end the Second Punic War and was given the province of Sicily with authorization to go to Africa if he thought it necessary, but the Senate registered its displeasure by refusing to let him levy troops, at which point – wait for it – Scipio took volunteers, equipping and financing his force through the socii and even building a fleet that way (Liv. 28.45.9-12).

In short, the Senate sometimes tried to trim the sails of generals it was displeased with – and Marius reportedly had gotten elected on a campaign platform of “to hell with the Senate” (Sall. Iug. 84.1) – by limiting the size of their armies or refusing to allow them to conduct a levy. And since 205 (a century before Marius), popular generals had occasionally juked this effort by the Senate by instead calling for volunteers, which the Senate could not stop. Marius is not doing something new in taking volunteers to supplement an army through the levy.

He also doesn’t keep doing it. After Marius wins in Africa with his volunteer-supplemented army (the bulk of which of course were still recruited through the dilectus under Metellus), he returns to Italy to take over the war against the Cimbri and Teutones but he doesn’t keep up the volunteer force, instead taking command of his predecessor Rutilius Rufus’ normally levied army (Front. Strat. 4.2.2). In practice, Marius probably took volunteers in part for that first army because the Senate was diverting available levy manpower towards the early phases of the Cimbric War (or at least that was a convenient excuse to kneecap him) – a series of costly military disasters for Rome which likely soaked up much of the manpower the Senate was willing to raise. Once Marius has access to that “primary” stream of manpower generated through the dilectus, he uses it and seems to stop using volunteers.

But what of recruiting the capite censi? Well, that isn’t quite new either, although it surely wasn’t typical. For one, it wasn’t that the poor absolutely never served; Polybius notes that the capite censi served in the fleet (Polyb. 6.19.2). But we also see non-assidui (assidui being the term for those wealthy enough to be liable for normal conscription) in a range of other emergencies. Livy reports in 329 a “crowd of sellularii [men who work sedentary trades, literally, ‘stoolsmen’], a type least suited for military service, were called into the army” (Livy 8.20.4), though the historicity of this report is questionable given the early date. In 296, Etruscan entrance into the Third Samnite War causes a draft of “not only the freeborn or the iuniores took the oath, but cohorts were made of seniores and centuries of freedmen” (Livy 10.21.4). Gellius (16.10.1) quotes Ennius reporting the proletarii were pulled into the armies in 280, presumably in response to Pyrrhus’ victory at Heraclea. And during the Second Punic War the Romans pulled out all of the stops, recruiting debtors and men convicted of capital crimes (Livy 23.14.3), enrolling slaves into the army (called the volones; you free them first and then draft them, Livy 27.38 and 28.10, Val. Max. 7.6.1) and as noted above, taking volunteers more generally.

As an aside, if you are wondering why the Romans seem in some of these to skip recruiting freeborn capite censi and go straight to freedmen and enslaved people, I think there are two answers here for this period. First, many of the available freeborn poor are probably already in service in the fleet. Second, there probably aren’t that many of them. Recall our chart of Roman social classes – the capite censi in the third century is quite small, almost certainly outnumbered by enslaved persons in Italy. But the population of Italy was rising over the third and especially second century and without adding new farmland, those new freeborn Romans may have swelled the ranks of the capite censi, leading to a much larger propertyless class by the late second century or the first century.¹ Consequently, there may have been a lot more capite censi worth recruiting by Marius’ day, when Rome no longer needed to keep a large navy at sea (not facing any naval powers in its wars) and the number of capite censi having risen.

Finally, Marius does not mark the end of the Roman dilectus! Evidently Roman conscription persisted at least to the end of the Roman civil wars, as Suetonius reports Augustus (perhaps when he was still Octavian) inflicting the traditional penalty of being sold into slavery for draft-dodging on a Roman eques who cut the fingers off of his two sons to make them ineligible for military service (Suet. Aug. 24.1). Indeed we have attestations of the dilectus in 55, 52, 50, 49, AD 6 and AD 9.² Even once the army is fairly clearly primarily a volunteer force, at least notionally the ability to hold a levy when necessary to fill the ranks remained “on the books” and Trajan (r. 98-117 AD) holds at least one levy because he punishes a father for the same reason Augustus had done (Dig. 49.16.4.12). So the traditional dilectus remained a thing Roman leaders could do well into the empire. In practice it seems safe to assume the system by the mid-first century is substantially ad hoc, as the census straight up doesn’t happen from 69 BC to 28 BC, which would make it hard to actually enforce the property requirements. But the process doesn’t stop in 107 and there’s no reason to suppose from 107 to 69, with the census being regularly conducted, that most annual levies were not conducted along traditional property lines.³

So the most we might say is that a one-time crisis expedient in earlier periods slowly becomes a standard way to supplement legions and then the standard way to recruit them, with the old normal method of the dilectus instead becoming the unusual way to supplement in a crisis. It’s unclear exactly when that shift-over point happens, but it sure isn’t in the career of Gaius Marius, who sits clearly in the “volunteers as a crisis response” side of the issue.

And what of the notion that Gaius Marius introduced both citizenship as a reward for service as a regular bonus and also that he instituted the paying of soldiers at the completion of a campaign to render them loyal? Well on the latter point, the Romans had been distributing spoils to the soldiers at the end of a campaign as a lump-sum payment since the beginning. This is exceedingly well reflected in Livy’s accounting of the years from 201 to 167 (where we have a nice continuous burst of Livy), see for instance Livy ::deep breath:: 30.45, 31.20, 33.23, 33.37, 34.46, 34.52, 36.40, 37.59, 39.5, 39.7, 40.34, 40.43, 40.59, 41.7, 41.13, 45.40, 45.43.⁴ And the idea that Roman victories might seize land which would then be settled as Roman coloniae, creating new land for Roman settlers was also not new (Wikipedia has a convenient list of Roman coloniae). So Marius is simply promising to do a thing Roman commanders regularly did, essentially saying, “serve with me, because I’m going to win and victory will make us rich”. Which is exactly the reason volunteers rushed to serve with Scipio Africanus and Scipio Aemilianus: they anticipated a lucrative victory for such well-regarded commanders.

And by now you may well be asking, “but wait, then when does the system change?” Because after all, I said that by the early empire, we can pretty clearly see an army primarily composed of professional, long-service volunteers who receive substantial retirement bonuses and are permanently stationed on the frontiers. Who is responsible for that? And in response, I give you, this guy.

It’s Augustus. It was always Augustus. Or at least I should say that is my view, given the evidence. Older scholarship – I think here of Keppie (1984) in particular – tended to assume that because most of the big changes happened with Marius (but we’ve seen they don’t) that Octavian/Augustus probably made only minimal changes to the military system he inherited from Julius Caesar. I don’t think that’s correct. I think if we look at the evidence in more detail it becomes clear that Augustus is the “break” (though not a clean break by any means) and that in fact we need to start regarding Augustus as a military reformer of some significant scale rather than merely the codifier of a Caesarian military system (though he probably does that too).

Augustus, after all, institutes regular bonuses for discharge, establishing a treasury funded by a regular tax to meet the expense rather than simply promising that he would win a lot and so soldiers would get rich off of their share of the booty (Res Gestae 17). And it’s not hard to see the problem he’s responding to – the massive military buildup of the Roman civil wars had left Octavian, as the victor, with the red-hot potato of hundreds of thousands of soldiers who were promised the spoils of victory, including large numbers of men who didn’t win but who, if not settled down somehow would disrupt the state (RG 3). Earlier in the civil wars, Octavian had used proscriptions and land confiscations to solve this problem but as emperor, he needed a permanent solution, thus the establishment of the aerarium militare and its discharge bonuses (praemia). Before that, you simply had generals promising to feast their soldiers off of the property of the vanquished; the civil wars had only changed that in that the vanquished were now Romans. It also establishes a standard length of service, creating that professional, long-service army.

There’s a related issue which is the fate of the citizen equites and the velites. Caesar’s armies in Gaul seem to have neither, so the assumption was that the shift to recruiting proletarii meant that these wealth-based distinctions (the richest Romans serve as equites, the poorest as velites) dropped away, leaving a uniform heavy infantry legion. And in a schematic it makes sense: both roles are absorbed by the auxilia and indeed Caesar makes use of a lot of Gallic cavalry auxiliaries. But as François Gauthier recently pointed out,⁵ it’s not all clear that the velites really did vanish in the late-second/early-first century. Cicero still refers to to them writing in the 40s (Cic. Fam. 9.20; Brut., 271) and their apparent absence in Caesar’s writing may well just be an accident of Caesar’s avoidance of technical language. Caesar doesn’t generally talk about hastati or triarii much either; he prefers milites (“soldiers”). Likewise, it’s clear the citizen cavalry – the equites – survived Marius; as Jeremiah McCall notes, we have good evidence for citizen equites at least as late as the 90s BC and suggests the citizen cavalry probably vanished in the 80s as a result of the Social War and Sulla‘s Civil War.⁶ It surely did not happen in 107 or 104.

Meanwhile the auxilia as a mature part of the Roman army really only emerge under Augustus, and not even right at the beginning of his reign either. Roman armies needed cavalry and light infantry to function, so once again we may not be looking at a clean break but rather a period of transition as a result of some generals preference for (non-Italian) allied or auxiliary cavalry and light infantry and the formalization of that system not in 107 with Marius but again in 27 with Augustus.

Marius is also sometimes credited with the idea of extending citizenship to non-citizens who served, which is a catastrophic misreading of one episode in his career. For one, this gets read as meaning that Marius extended citizenship to all of the Italians in his army or that he made it standard to do so. Note for instance this line pulled from Wikipedia:

Finally, Marius granted citizens of the Italian allies (Etruria, Picenum, etc.) full Roman citizenship if they fought for Rome and completed a period of service in the Roman army.

[Dated] 6/25/2023, specified in the hope this page changes to be less wrong.

And that’s very much not right either. We have evidence for only a handful of citizenship extensions by Marius. In particular, of his army he extended citizenship to just two cohorts (c. 1,000 men) from Camerinum (Plut. Mor. 202D, Cic. Pro Balbo 46.). I can only assume this gets misunderstood because some writers don’t know their unit sizes, but Marius had 32,000 men in his army at Vercellae (101 BC), probably something like half of which were socii. These two cohorts were a comparatively tiny fraction. Marius also seems to have selected a very small number of his other socii veterans for citizenship (Cic. Pro Balbo 48), but there was no blanket grant of citizenship. Of course there wasn’t, this issue remained substantially unsolved until the Social War (91-87BC); if Roman levies had been calmly minting new citizens out of thousands of Italians through the 90s, there would hardly have been a cause for the Social War.

Instead, citizenship as a reward for service is an artifact of the imperial period and the auxilia. The Roman use of non-Roman, non-socii troops to supplement their armies was not new, but it emerged as a formalized, permanent part of the Roman army not during the civil wars – where such units where both ad hoc but also not nearly so numerous – but under the reign of Augustus, coming to form about half of the army by the end of his reign (Tac. Ann. 4.5; on the emergence of the auxilia, see I. Haynes, Blood of the Provinces (2013)). Indeed, as Haynes notes (op. cit. 49), it is actually only under Tiberius (r. 14-37) that we get direct evidence of citizenship grants to auxilia and the practice even then seems at least somewhat irregular (though it comes to be regularized).

In short that, the notion that Gaius Marius instituted the pattern of granting citizenship to serving non-citizens on discharge is simply wrong; that’s not in our sources. That doesn’t become consistent until Tiberius well over a century later. Gaius Marius did recruit volunteer capite censi into his army once but didn’t make a habit of it and as such isn’t a major reformer so much as a key step in a slow process of change which reaches its decisive point probably under Augustus, more than half a century after Gaius Marius died. He wasn’t the first to do either thing, whatever our sources say.

Bret Devereaux, “Collections: The Marian Reforms Weren’t a Thing”, A Collection of Unmitigated Pedantry, 2023-06-30.

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1. For more on the dynamics of this, see N. Rosenstein, Rome at War (2004), as this is part of his central argument.

2. For textual references, see Brunt, Italian Manpower (1971), 636-7.

3. We do not know how that process would have accounted for the massive expansion of the Roman citizen class due to the Social War. But evidently it did!

4. These were happily already compiled by Brunt, op. cit., 394.

5. “Did velites Really Disappear in the Late Roman Republic?” Historia 70 (2021).

6. J.B. McCall, The Cavalry of the Roman Republic (2002), 100-113..