… once elected and inaugurated, the consuls select the day of the dilectus. Polybius is quite wordy in his description of the process, but it gives us a nice schematic vision of the process. In practice, there are two groups here to keep track of in parallel: the dilectus of Roman citizens, but also the mobilization of the socii who will reinforce those Roman legions once raised. The two processes happen at the same time.

So, on the appointed day(s), Polybius tells us all Romans liable for service of military age assemble in Rome and are called up on the Capitoline Hill for selection. This was a point that raised a lot of skepticism from historians,¹ mostly concerning the number of people involved, but those concerns have all pretty much been resolved. While there might have been something like 323,000 Roman citizen males in the third or second century, they’re not all liable for general conscription, which was restricted to the iuniores – Roman citizen men between the ages of 17 and 46, who numbered fewer, probably around 228,000; seniores in theory could be conscripted, but in practice only were in an emergency. In practice the number is probably lower still as unless things were truly dire, men in their late 30s or 40s with several years of service could be pretty confident they wouldn’t be called and might as well stay home and rely on a neighbor of family member to report back in the unlikely event they were called. That’s still, of course, too many to bring up on to the Capitoline or to sort through calling out names, but as Polybius notes they don’t all come up, they’re called up by tribe. The Roman tribes were one of Rome’s two systems of voting units (the other, of centuries, we’ll come to in just a moment) and there were 35 of them, four urban tribes for those living in the city and 31 rural tribes for those living outside the city.

So what is actually happening is that the consul sets the date for the dilectus, then assigns his military tribunes to their legions (this matters because the tribunes will then do a round-robin selection of recruits to ensure each legion is of equivalent equality), then calls up one tribe at a time, with each tribe having perhaps around 6-7,000 iunores in it. Conveniently, the Capitoline is plenty large enough for that number, with estimates of its holding capacity tending to be between 12,000 and 25,000 or so.² And while Polybius makes it seem like all of this happens on one day, it probably didn’t. Livy notes of one dilectus in 169, conducted in haste, was completed in 11 days; presumably the process was normally longer (though that’s 11 days for all three steps, not just the first one, Livy 43.14.9-10).

Once each tribe is up on the Capitoline, recruits are selected in batches; Polybius says in batches of four, but this probably means in batches equal to the number of legions being enrolled, as Polybius’ entire schema assumes a normal year with four legions being enrolled. Now Polybius doesn’t clarify how selection here would work and here Livy comes in awfully handy because we can glean little details from various points in his narrative (the work of doing this is a big chunk of Pearson (2021), whose reconstruction I follow here because I think it is correct). We know that the censors compile a list not just of Roman senators but of all Roman citizen households, including self-reported wealth and the number of members in the household, updated every five years. That self-reported wealth is used to slot Romans into voting centuries, the other Roman voting unit, the comitia centuriata; those centuries correspond neatly to how Romans serve in the army, with the equites and five classes of pedites (infantry). Because of a quirk of the Roman system, the top slice of the top class of pedites also serve on horseback, and Polybius is conveniently explicit that the censors select and record this too.

So at dilectus time, the consuls, their military tribunes (and their state-supplied clerk, a scriba) have a list of every Roman citizen liable for conscription, with the century and tribe they belong to, the former telling you what kind of soldier they can afford to be when called and the latter what group they’ll be called in. And we know from other sources (Valerius Maximus 6.3.4) that names are being read out, rather than just, say, selecting men at sight out of a crowd. That actually makes a lot of sense as dilectus (“select”) may really be dis-lego, “read apart”, from lego (-ere, legi, lectum) “to read”.³ And that matters because the other thing the Romans clearly have a record of us who has served in the past. We know that because in an episode that is both quite famous but also really important for understanding this process, in 214 – after four of the most demanding years of military activity in Roman history, due to the Second Punic War – the Roman censors identified 2,000 Roman iuniores who had not served in the previous four years (or claimed and been granted an exemption), struck them from the census rolls (in effect, revoking their citizenship) and then packed them off to serve as infantry (regardless of their wealth) in Sicily.⁴

So what happens as each tribe comes up is that the tribunes can call out the names – in batches – of men with the least amount of service, of the particular wealth categories they are going to need to fill out the combat roles in the legion.⁵ The tribunes for each legion pick one recruit from each batch that comes up, going round-robin so every legion gets the same number of first-picks. Presumably once the necessary fellows are picked out of one tribe, that tribe is sent down the Capitoline and the next called up.

Once that is done the oath is administered. This oath is the sacramentum militare; we do not have its text in the Republic (we do have the text for the imperial period), but Polybius summarizes its content that soldiers swear to obey the orders of the consuls and to execute them as best they are able. The Romans, being practical, have one soldier swear the full oath and then every other soldier come up and say, “like that guy said” (I’m not even really joking, see Polyb. 6.21.3) to get everyone all sworn in. Of course such an oath is a religious matter and so understood to be quite binding.

Then the tribunes fix a day for all of the new recruits to present themselves again (without arms, Polybius specifies) and dismiss them. Strikingly, Polybius only says they are dismissed at this point – not, as later, dismissed to their homes. This makes me assume that the oath being described is administered tribe by tribe before the tribe is sent down (this also seems likely because fitting the last tribe and four legions worth of recruits on the Capitoline starts to get pretty tight, space-wise). Selecting with the various tribes might, after all, take a couple of days, so the tribunes might be telling the recruits of the first few tribes what day the entire legion will be assembled (that’ll be Phase II) after they’ve worked through all of the tribes. Meanwhile, once your tribe was called, you didn’t have to hang around in Rome any longer, if you weren’t selected you could go home, while the picked recruits might stick around in Rome waiting for Phase II.

That leads to the other logistical question for Phase I: the feasibility of having basically all of the iuniores in Rome for the process. Doubts about this have led to the suggestion that perhaps the dilectus in Rome was mirrored by smaller versions held in other areas of Roman territory in Italy (the ager Romanus) for Roman citizens out there. The problem with that assumption is that the text doesn’t support it. The Romans send out conscription officers (conquisitores) exactly twice that we know of, in 213 and 212 (Livy 23.32.19 and 25.5.5-9) and these are clearly exceptional responses to the failure of the dilectus in the darkest days of the Second Punic War (the latter is empowered to recruit under-age boys if they look strong enough to bear arms, for instance). But I also think it was probably unnecessary: this was a regular occurrence, so people would know to make arrangements for it and the city of Rome could prepare for the sudden influx of young men. This is, after all, also a city with regular “market days”, (the nundinae) which presumably would also cause the population to briefly swell, though not as much. And we’re doing this in an off-time in the agricultural calendar, so the farmhands can be spared.

Moreover, Rome isn’t that far away for most Romans. Strikingly, when the Romans do send out conquisitores, they split them with half working within 50 miles of Rome and half beyond that (Livy 25.5.5-9). The implication – that most of the recruits to be found are going to be within that 50 mile radius – is clear, and it makes a lot of sense given the layout of the ager Romanus. Certainly there were communities of Roman citizens farther out, but evidently not so many. Fifty miles down decent roads is a two-day walk; short enough that Roman iuniores could fill a sack with provisions, walk all the way to Rome, stay a few days for the first phase of the dilectus and walk all the way back home again at the end. We’re not told how communities farther afield might handle it, but they may well have trekked in too, or else perhaps sent a few young men with instructions to bring back a list of everyone who was called.

Meanwhile the other part of this phase is happening: the socii. Polybius reports that “at the same time the consuls send their orders to allied cities in Italy, which they with to contribute troops, stating the numbers required and the day and place at which the men selected must present themselves.”⁶ Livy gives us more clarity on how this would be done, providing in his description of the muster of 193 the neat detail that representatives of the communities of socii met with the consuls on the Capitoline (Livy 34.36.5). And that makes a ton of sense – this is happening at the same time as the selection, so that’s where the consuls are.

We also know the consuls have another document, the formula togatorum, which spells out the liability of each community of socii for recruits; we know less about this document than we might like. Polybius tells us that the socii were supposed to compile lists of men liable for recruitment (Polyb. 2.23-4) and an inscription of the Lex Agraria of 111 BC refers to, “the allies or members of the Latin name, from whom the Romans are accustomed to demand soldiers in the land of Italy ex formula togatorum“.⁷ That then supplies us with a name for the document. Finally, we know that in 177, some of the socii complained that many of the households in their territory had migrated into other communities but that they conscription obligations had not been changed (Livy 41.8), which tells us there was a formal system of obligations and it seems to have been written down in something called the formula togatorum, to which Polybius alludes.

What was written down? Really, we don’t know. It has been suggested that it might have been a sliding scale of obligations (“for every X number of Romans, recruit Y number of Paeligni”) or a standard total (“every year, recruit Y Paeligni”) or a maximum (“the total number of Paeligni we can demand is Y, plus one more guy whose job is to throw flags at things”.). In practice, it was clearly flexible,⁸ which makes me suspect it was perhaps a list of maximum capabilities from which the consuls could easily compute a fair enough distribution of service demands. A pure ratio doesn’t make much sense to me, because the socii come in their own units, which probably had normal sizes to them.

So, while the military tribunes are handling the recruitment of citizens into the legions, the consuls are right there, but probably focused on meeting with representatives of each community of the socii and telling them how many men Rome will need this year. Once told, those representatives are sent back to their communities, who handle recruitment on their own; Rome retains no conscription apparatus among the socii – no conscription offices, no records or census officials, nada. The consuls spell out how many troops they need and the rest of it was the socii‘s elected official’s problem.

Bret Devereaux, “Collections: How To Raise a Roman Army: The Dilectus“, A Collection of Unmitigated Pedantry, 2023-06-16.

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1. Particularly in P.A. Brunt, Italian Manpower (1971).

2. Pearson (2021) compiles them; the issue is also discussed in Taylor (2020).

3. The philological argument here is Pearson (2021), 16-17. It is not air-tight because legere has a lot of meanings, including “to pick out” along with “to read”. That said, given that the verb of being recruited into the army is conscribere (“to write together, to conscript”), there really is a strong implication that this is a process with written records, which the rest of the evidence confirms. I think Pearson may or may not be right about the understood meaning of dilectus implying writing, but the process surely involved written records, as she argues.

4. A punishment post, this is also where the survivors of the Battle of Cannae were sent. Both groups remain stuck in Sicily until pulled into Scipio Africanus’ expedition to Africa in 205, so these fellows don’t get to go home and get their citizenship back until the conclusion of the war in 201.

5. In particular, we generally assume the lowest classes of Roman pedites probably could only afford to serve as light troops, the velites, while the wealthy equites had their own selection procedure for the cavalry done first. Of course, rich Romans not selected for the cavalry might serve as infantrymen if registered in the centuries of pedites which is presumably how Marcus Cato, son of the Censor, ends up in the infantry at Pydna (Plut. Aem. 21).

6. Polyb. 6.21.4. Paton’s trans.

7. Crawford, Roman Statutes (1996), 118 for the text of that inscription.

8. Something pointed out by L. de Ligt in his chapter in the Blackwell A Companion to the Roman Army (2007).