List of Roman auxiliary regiments

This article lists the Roman auxiliary regiments of the Imperial Roman army attested in the epigraphic record, by province of deployment in the reign of the emperor Hadrian (r. 117-38), the period with the most abundant evidence. For the history, organisation and equipment of these regiments, see Roman auxiliaries.

In addition, an index of regimental names is provided that explains the origin of the names, most of which are based on the names of the subject tribes or cities of the empire where they were originally recruited. (As time went by, they became staffed by recruits from anywhere, especially from the province where they were deployed.)

Types of regiment
During the Principate era until AD 212, auxiliary regiments, called auxilia by the Romans, were formations kept separate from the legions, who were recruited from Roman citizens only. Auxilia were mostly recruited from the peregrini, i.e. subjects of the Roman empire who did not hold Roman citizenship: the vast majority of the empire's inhabitants in the 1st and 2nd centuries AD (in 212 AD, all the inhabitants of the empire were granted Roman citizenship).

There were three basic types of auxiliary regiment: alae (lit: "wings"), which contained cavalry only (official strength: 480 men); cohortes ("cohorts"), which contained infantry only (480); and cohortes equitatae,  which were infantry cohorts with a cavalry contingent attached (600 men, of which 480 infantry and 120 cavalry). A number of regiments, of all three types, were designated sagittariorum, indicating that their members were equipped as archers. After ca. AD 80, a minority of regiments (ca. 12%) were enlarged and designated milliariae, nominally 1000-strong, but in reality containing 720, 800 and 1,040 effectives respectively.

Contents of tables
Table I below lists auxiliary regiments during the rule of the emperor Hadrian (AD 117-38), for which there is the most comprehensive evidence. The table does not show regiments that were attested to in the 1st century but that, according to Holder, were dissolved by 117, nor those that were probably founded after 138. The precise number of regiments that existed at this time is disputed (e.g., 327 per Spaul; 367 per Holder). This discrepancy is due to the existence of several units with the same serial number and name, but attested in various provinces: were they different units, or the same unit moved around? In the table, Holder's estimate has been followed. In addition, 14 units attested until ca. 100, which Holder considers likely but not certain to have survived into Hadrian's reign are also included to present all possible units (making a total of 381 units). The regiments are listed by the Roman province where they were deployed in ca. 130.

Table II is a glossary of regimental names, the majority of which were ethnic, i.e., derived from the name of the native tribe or city-state of the empire where the regiment was originally raised. The table gives the tribe's name, territory and language-group.

Ethnic composition of regiments
The rule of the founder-emperor Augustus (30 BC - AD 14) saw the foundation of the majority of the regiments attested in Hadrian's time. In the earlier part of this period, regiments were raised from, and named after, individual tribes e.g. Campagonum, Trevirorum and Bessorum. Later, units were raised from and named after broad national groups e.g. Hispanorum, Gallorum, Thracum.

There is very little evidence concerning the organisation and policies of auxiliary recruitment. The ethnic origins of auxiliary recruits are attested in only a tiny fraction of cases. For example, the Cohors II Gallorum veterana equitata must have recruited ca. 8,000 effectives over its probable lifespan of ca. 250 years (assuming an average performed service of 15 years). But the origins of only 2 rankers are known. Conclusions about auxiliary recruitment drawn by scholars from the available evidence must therefore be regarded as tentative.

According to Holder, during the Julio-Claudian era (14-68), a regiment's ethnic identity was preserved to some extent, with evidence of continued recruitment from the original people. By the time of Hadrian, however, a regiment's name, in most cases, probably represented the ethnic origin of few, if any, of its members. This is because in the Flavian era (69-96), as a matter of deliberate policy, most regiments were deployed in provinces far from their original home and drew the majority of their recruits from local natives and the rest from all parts of the empire. In most cases, therefore, a regiment's name had become an identification tag devoid of ethnic significance. A regiment deployed long-term in the same province would thus, over time, acquire the ethnic character of its host population.

There are exceptions to this rule:
 * A minority of regiments remained stationed in their original home province, e.g., cohors I Delmatarum mill eq, still attested in Dalmatia in 130.
 * Regiments founded a relatively short period before 130, e.g., the cohors I Aelia Dacorum stationed in Britain in 130 would probably still have contained mostly Dacian recruits at this time, as it had been established by Hadrian only about a decade earlier.
 * Some specialised regiments (e.g., Syrian archers) and the elite Batavi show some evidence of continued preferential recruitment from their original province.

TABLE I: Regiments attested in the reign of Hadrian
To access the table of auxiliary regiments for the province of your interest, click on the relevant note.

KEY:
 * Britannia (England/Wales)
 * Germania Inferior (S Netherlands/NW Rhineland)
 * Germania Superior (S Rheinland/Alsace-Lorraine)
 * Raetia/Noricum (Germany S of Danube/Switzerland/Austria)
 * Pannonia Sup & Inf (W Hungary/Slovenia)
 * Moesia Superior (Serbia)
 * Moesia Inferior (N Bulgaria, coastal Romania)
 * Dacia (Romania)
 * Cappadocia (Central/East Turkey)
 * Syria inc Judaea, Arabia (Syria, Lebanon, Palestine/Israel, Jordan)
 * Aegyptus (Egypt)
 * Mauretania inc Africa Pro (Tunisia, Algeria, Morocco)
 * Other provinces

c.R. = civium Romanorum ("of Roman citizens"): an honorific title eq = equitata (i.e. contains a cavalry contingent) sagitt = sagittariorum (archer unit) unit in bold type = milliaria (double-strength) regiment

GLOSSARY OF NON-ETHNIC REGIMENTAL NAMES

NB: Where a regiment carries the name of a person (other than an imperial name, see below), e.g. ala Sulpicia, the name in most cases is that of the regiment's first, or early, praefectus (regimental commander). In the Augustan era, commanders of auxiliary units were often Roman legionary centurions, or native chieftains e.g. ala Gallorum Atectorigiana, which was probably once commanded by a Gallic chieftain named Atectorix. (Later, the emperor Claudius restricted auxiliary commands to Roman knights only).

(1) imperial dedications

N.B. In the 4th century, Valeria referred to emperor Diocletian (Aurelius Valerius Diocletianus, r.284-305) and Flavia to Constantine I (Flavius Valerius Constantinus, r.312-337) or some of his successors.
 * Augusta: founded by emperor Augustus (r. 30 BC - AD 14), or honoured with this title by any of his successors
 * Claudia: founded by, or honoured by, one of: Tiberius (r.14-37), Caligula (37-41) or Claudius (41-54), all of whom were members of the Claudii clan
 * Flavia: Vespasian (Titus Flavius Vespasianus r.69-79) or one of his two sons and successors, Titus (79-81) or Domitian (81-96)
 * Ulpia: Trajan (Marcus Ulpius Traianus r.98-117)
 * Aelia: Hadrian (Publius Aelius Hadrianus r.117-138)
 * Aurelia: Marcus Aurelius (r.161-180)
 * Septimia: Septimius Severus (r.197-211)

(2) names of regiments originally raised by the emperor Augustus during the Illyrian revolt crisis (AD 6-9) from Roman citizens not admissible to legions (i.e. vagrants, convicts, debtors and freed slaves):

PS: After their initial recruitment of Roman citizens, these regiments recruited non-citizens (peregrini) like all other regiments.
 * civium Romanorum: regiment originally composed of Roman citizens (inc freed slaves)
 * ingenuorum: regiment originally free-born (ingenui) Roman citizens
 * voluntariorum: regiment originally volunteers (voluntarii), in reality slaves freed in return for military service during the Illyrian revolt crisis

(3) other non-ethnic regimental names:


 * classica: the regiment was originally recruited, probably in the Illyrian emergency, from naval personnel (from classis = "fleet"), who were mostly non-citizens. Also nauticarum (from nautae= "sailors") and maritima.
 * praetoria: originally a cohort of the Praetorian Guard in Rome. Apparently a detachment of the cohort was left behind at the end of an imperial campaign, presumably to form the core of a new auxiliary cohort, retaining the prestigious name.
 * singularium: ala formed around members of the elite equites singulares Augusti (imperial horseguards), left behind to reinforce frontier at the end of an imperial campaign.
 * contariorum: specialised regiment of lancers (contarii) from contus (a long lance)
 * dromedariorum: specialised regiment of camel-mounted troops for desert warfare

(4) regimental epithets:


 * civium Romanorum (c.R. for short): title awarded by the emperor to a regiment for signal valour. All current (but not future) members would be granted Roman citizenship, and the regiment would retain the title in perpetuity.
 * veterana: uncertain meaning: may have been used to distinguish older unit from a newer unit with the same serial number and name
 * tironum: from tirones ("trainees")

TABLE II: Index of ethnic regimental names
Linguistic group code


 * C = Celtic language group
 * X = non Indo-European language
 * X/C = non Indo-European base with strong Celtic influence
 * X/S = Semitic language group