Alpinorum auxiliary regiments

Most regiments carried a number and a name (normally a peregrini tribal name) e.g. I Raetorum. A few regiments had no number. A confusing aspect of auxiliary unit nomenclature is that in some cases, more than one regiment can appear in the record with the same number and name e.g. there are two I Raetorum units attested in the 2nd century. In a few cases there is dispute as to whether it really is two distinct regiments, as opposed to the same regiment moving from one province to another or two detachments of the same regiment in different provinces at the same time. But in most cases, there is no doubt two separate regiments are involved. They can usually be distinguished by whether one is equitata or not, or has a c.R. title or not e.g. I Raetorum and I Raetorum c.R.

The explanation for duplicated names is that where more than one series of cohorts was raised from the same original tribe, numbering would start from 1 again, especially if the second series was raised by a different emperor. The same factor affected the numbering of legions.

There were three basic types of auxiliary regiment. (1) an ala (literally "wing") was a purely cavalry regiment of 480 horse. (2) a cohors ("cohort") was a purely infantry regiment of 480 foot. (3) a cohors equitata was a mixed infantry/cavalry regiment of 600 men (480 infantry, 120 cavalry). A minority of regiments were denoted milliaria which meant they were nominally double-strength: in practice 720 men for an ala milliaria, 800 for a cohors milliaria and 1,040 (800 inf/240 cav) for a cohors equitata milliaria. In addition, some regiments were denoted sagittaria (from sagitta, "arrow") meaning they were composed of archers.

The honorific title civium Romanorum (c.R. for short) was normally awarded by the emperor for valour to an auxiliary regiment as a whole. The award would include the grant of Roman citizenship to all the regiment's men, but not to subsequent recruits to the regiment. The regiment, however, would retain the prestigious title in perpetuity.[1] Until 212, only a minority of the empire's inhabitants (inc. all Italians) held full Roman citizenship. The rest were denoted peregrini, a second-class status. Since the legions admitted only citizens, peregrini could only enlist in the auxilia. Citizenship carried a number of tax and other privileges and was highly sought-after. It could also be earned by serving the minimum 25-year term in the auxilia. In 212, all the inhabitants of the empire were granted full Roman citizenship and so the title became redundant.

The literary evidence for auxiliary regiments is almost non-existent. Unlike for the legions, ancient Roman historians only rarely mention the auxilia at all, and never denote a specific unit. Knowledge of the auxilia is therefore dependent on inscriptions found bearing the regiment's name. Many of these are not datable (even roughly) and so are of limited value.

The epigraphic record includes: (1) inscriptions from Roman military diplomas, which were bronze certificates of Roman citizenship awarded to peregrini soldiers who completed the minimum 25 years' service in the auxilia: these are very useful as, if complete, they contain a precise date and the province in which the regiment was serving at the time (as well the name, origin and rank of the recipient). (2) tiles or bricks, used in building work on Roman forts, stamped with the regiment's name. These show the forts where a regiment may have been based, but are rarely datable. (3) votive stone altars or tablets, and tombstones. These can indicate the addressee's origin if they are found in provinces away from the regiment's base. A minority are datable.

The datable epigraphic record is very incomplete. Most of the regiments attested in the 2nd century are believed by inference to have been established in the early Julio-Claudian period, i.e. before 37 AD, but very few have left records dating to before 75.

Auxiliary regiments were mostly stationed in one province long-term. The Flavian (69-96) saw a lot of changes in auxiliary deployment in what appears a deliberate policy of deploying regiments away from their original home province. After that, deployments generally became much more settled, with most units remaining in the same province throughout the 2nd and 3rd centuries. Regiments, or detachments of regiments, could be summoned to participate in a major campaign elsewhere, but this would usually be just a short-term deployment.

Auxiliary regiments were normally attached, for operational purposes, to a particular legion. The praefectus (commander) of the regiment would report to the legatus legionis (legion commander). Auxiliary regiments were mostly housed in Roman forts in frontier provinces or even beyond the empire's settled borders, to keep watch on barbarian activity. A regiment would usually garrison a fort alone, but sometimes shared with another regiment if it was a larger fort. More rarely, regiments appear to have been housed in the castra legionaria (legionary fortress) of the legion they were attached to. Although inscriptions, especially the regiment's tile- and brick-stamps, can attest which forts the regiment occupied, most are not datable and so it is rarely possible to reconstruct a precise sequence or chronology of forts occupied.

Auxiliary personnel left traces in inverse proportion to their numbers, for the obvious reason that memorials such as votive altars or tombstones were expensive and could be better afforded the higher the rank. Thus the names of more praefecti (commanders) and principales (officers) are attested than of caligati (common soldiers, literally "booted" from caliga, the Roman marching sandal), even though caligati constituted over 80% of personnel. The origin of the dedicator/deceased person is often impossible to establish. Sometimes the origin is recorded in the inscription. More commonly, it can be inferred from the location of the inscription if it is away from the province in which the regiment was based.