Late Roman Army Ranks - Numeri/Limitanei

[Nathan Ross]

the difference between the Campidoctor and Armidoctor, I had no idea the two roles were distinct.

'Armidoctores' turn up (I think) only in inscriptions from the Principiate. The later Campidoctor (senior NCO) role was different.

Vegetius mentions 'doctores armorum' training soldiers, which could refer to the same thing. Alternatively he may be thinking of the senior soldier grade of armatura (see below), which might have had something to do with weapon proficiency or training.

So besides the centurion becoming an ordinarius, do we know the rest of the hierarchy?

We do indeed! Based on the inscription from Perge, which details the organisation of a numerus stationed there in c.AD500, and a few other sources, the later 'legion' (plus limitanei) rank hierarchy probably went like this:

Tribune/Praefect/Praepositus - this would be the unit commander. Generally all field army units and most frontier 'cohorts' are commanded by tribunes, while frontier cavalry units and legions, and some 'numeri', are led by Prefects or Praepositi.

Vicarius - deputy to the tribune. Perhaps also called Tribunus Minor. Maybe a temporary rank or post?

Ordinarius - this was the centurion-grade officer of the late legions and limitanei.

Campidoctor - originally a drill master, by the later empire the most senior soldier in the unit. Whether he was one of the Ordinarii, or a separate rank, is unknown.

Augustales and Flaviales - these are senior soldier or NCO grades, and appear in both legions and limitanei units.

Armaturae/Semissales - senior soldier grades, of various sorts.

Besides these men, there was the Optio (who functioned more like a subunit clerk at this date), the signifer (standard bearer, aka draconarius), various musicians, and the munifices, or milites (common soldiers). A clerk called an actuarius turns up in some sources as well. Beneficiarii are listed on the Perge tablet and perhaps acted as aides to the commanding officer.

Things do get confusing when we consider other sources though - the mythical martyr story of the 'Theban Legion' (probably written in the later 4th century) has the legion commanded by a primicerius named Mauricius, together with campidoctor Exuperius and the senator militum Candidus. These appear to be ranks or grades from the auxilia palatina - it may be that the churchman who wrote the story knew no different, but we can't rule out these ranks perhaps crossing over to (some of) the legions and/or other units by this date. A limitanei numerus mentioned in a 6th century papyrus from Patermouthis in Egypt features a primicerius...

Senator is a weird rank, and probably a very late one. It appears among the c.AD400 tomb inscriptions from Concordia among the auxilia palatina, and elsewhere in the schola scutariorum. So it was most likely part of that system of ranks - perhaps a title for the senior ducenarius?

am I right in assuming that the domesticus/protectores domestici were the chief of staff and adjutants to the Tribunus? I thought I read somewhere that protectores domestici were also bodyguards?

The Protectores were originally set up as bodyguards to the emperors, featuring men personally selected from the centurionate. Later they were divided into the Protectores Domestici, a sort of staff college and officer-training corps with a bodyguard function (many of whom were the sons of either barbarian nobles or prominent Romans, like Ammianus Marcellinus), and the ordinary Protectores who fulfilled various independent roles.

The domesticus who appears on some very late army lists was not one of these men - he was apparently a servant to the commanding officer.

I had no idea the Iuniores/Seniores distinction happened within a unit. I thought that was solely a distinction between east/west.

The usual theory is that Seniores and Iuniores were different units, the second being perhaps formed from a cadre or offshoot of the first. Here is a recent discussion of the subject.

would it be within the realms of possibility that a scouting unit had both infantry and cavalry, as per the old Auxiliary units?

I would think that very likely!

Incidentally, you might be interested in a novel called Frontier Wolf by Rosemary Sutcliff - about a legion centurion (I think) sent to mid 4th century North Britain to command a unit of frontier scouts. She uses a melange of late Roman ranks and titles, but the overall effect feels pretty authentic.