List of Roman auxiliary regiments#Britannia

During most of the Principate era, until AD 212, auxiliary regiments, called {{lang|la|auxilia}} by the Romans, were formations kept separate from the legions, who were recruited from Roman citizens only. {{lang|la|Auxilia}} were mostly recruited from the peregrini, the vast majority of subjects in the Roman Empire who did not hold Roman citizenship. (in AD 212, all the inhabitants of the empire were granted Roman citizenship).

There were three basic types of auxiliary regiment:

• {{lang|la|alae}}, which contained only cavalry and consisted nominally of 480 soldiers
• {{lang|la|cohortes peditatae}} or simply {{lang|la|cohortes}}, which contained only infantry and consisted nominally of 480 soldiers
• {{lang|la|cohortes equitatae}}, which contained infantry with an attached cavalry contingent and consisted nominally of 600 soldiers, of which 480 were infantry and 120 were cavalry

A number of regiments, of all three types, were designated {{lang|la|sagittariorum}} (sagitt), indicating that their members were equipped as archers. After about AD 80, about 12 percent of regiments were enlarged from the {{lang|la|quingenarie}} size and designated {{lang|la|milliarie}}, which nominally consisted of 1000 soldiers, but in reality consisted of 720 soldiers, 800 soldiers, and 1040 soldiers respectively.

Table I below lists auxiliary regiments during Hadrian's rule, 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 AD 117, nor those that were probably founded after AD 138. The precise number of regiments that existed during Hadrian's rule is disputed.{{efn|The number of units is 327 according to Spaul and 367 according to Holder. This discrepancy is due to the existence of several units with the same serial number and name, but attested in various provinces. It is not clear if they were different units or the same units moved around. In the table, Holder's estimate has been followed. In addition, 14 units attested until about {{CE|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 c. AD 130.

• Boldface entries: denotes a unit of double strength
• eq: denotes a part-mounted unit
• c.R: denotes a unit composed of Roman citizens
• sagitt: denotes a unit composed of archers

The rule of the first 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, for example {{lang|la|Campagonum}}, {{lang|la|Trevirorum}} and {{lang|la|Bessorum}}. Later, units were raised from and named after broad national groups, for example {{lang|la|Hispanorum}}, {{lang|la|Gallorum}}, and {{lang|la|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

{{lang|la|cohors II Gallorum veterana equitata}} must have recruited a calculated 8,000 soldiers over its probable lifespan of about 250 years but the origins of only two rankers are known.{{efn|The calculation assumes an average performed service of 15 years}} Conclusions about auxiliary recruitment drawn by scholars from the available evidence are regarded as tentative.

According to Holder, during the Julio-Claudian dynasty (AD 14–68), regimental 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 during the Flavian dynasty (AD 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., {{lang|la|cohors I Delmatarum {{abbr|mill|milliaria}} {{abbr|eq|equitata}}}}, still attested in Dalmatia in AD 130.
• Regiments founded a relatively short period before AD 130, for example {{lang|la|cohors I Aelia Dacorum}} which was stationed in Roman Britain in AD 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, such as Syrian archers and the elite Batavi show some evidence of continued preferential recruitment from their original province.

{{Main|Roman auxiliaries in Britain}}

Some regiments were named after other people, for example ala Sulpicia after its first, or early, {{lang|la|praefectus}}. In the Augustan era, commanders of auxiliary units were often Roman legionary centurions, or native chieftains. For example, {{lang|la|ala Gallorum Atectorigiana}} was probably once commanded by a Gallic chieftain named Atectorix. Later, emperor Claudius restricted auxiliary commands to the lower aristocratic class of {{lang|la|equites}} only.

{{glossary|style=padding-left:1.6em}}

{{term|term=Augusta|content={{lang|la|Augusta}}}}

{{defn|founded by emperor Augustus (r. BC 30–AD 14), or honoured with this title by any of his successors}}

{{term|term=Claudia|content={{lang|la|Claudia}}}}

{{defn|founded by, or honoured by, one of: Tiberius (r. AD 14–37), Caligula (r. AD 37–41), or Claudius (r. AD 41–54), all of whom were members of the gens Claudia}}

{{term|term=Flavia|content={{lang|la|Flavia}}}}

{{defn|Vespasian (r. AD 69–79) or one of his two sons and successors, Titus (r. AD 79–81) or Domitian (r. AD 81–96)}}

{{term|term=Ulpia|content={{lang|la|Ulpia}}}}

{{defn|Trajan (r. AD 98–117)}}

{{term|term=Aelia|content={{lang|la|Aelia}}}}

{{defn|Hadrian (r. AD 117–138)}}

{{term|term=Aurelia|content={{lang|la|Aurelia}}}}

{{defn|Marcus Aurelius (r. AD 161–180)}}

{{term|term=Septimia|content={{lang|la|Septimia}}}}

{{defn|Septimius Severus (r. AD 197–211)}}

{{glossary end}}

In the 4th century, Valeria referred to emperor Diocletian (r. AD 284–305) and Flavia to Constantine I (r. AD 312–337) or one of his successors.

Names of regiments originally raised by emperor Augustus during the Illyrian revolt (AD 6–9) from Roman citizens unsuitable for service in legions, such as vagrants, convicted criminals, debtors, and emancipated slaves:

{{glossary|style=padding-left:1.6em}}

{{term|term=civium Romanorum|content={{lang|la|civium Romanorum}}}}

{{defn|defn=regiment originally composed of Roman citizens (including emancipated slaves)}}

{{term|term=ingenuorum|content={{lang|la|ingenuorum}}}}

{{defn|defn=regiment originally composed of free-born ({{lang|la|ingenui}}) Roman citizens}}

{{term|term=voluntariorum|content={{lang|la|voluntariorum}}}}

{{defn|defn=regiment originally composed of volunteers ({{lang|la|voluntarii}}), in reality slaves freed in return for military service during the Illyrian revolt{{cite book|location=London [u.a.]|publisher=Thames & Hudson|last=Goldsworthy|first=Adrian

|title=The Complete Roman Army

|year=2003

|isbn=0-500-05124-0|page=64}}}}

{{glossary end}}

After their initial recruitment of Roman citizens, these regiments recruited non-citizens ({{lang|la|peregrini}}) like all other regiments.

{{glossary|style=padding-left:1.6em}}

{{term|term=classica|content={{lang|la|classica}}}}

{{defn|defn=the regiment was originally recruited, probably during the Illyrian revolt, from naval personnel (from classis = "fleet"), who were mostly non-citizens}}

{{term|term=nauticarum|content={{lang|la|nauticarum}}}}

{{defn|defn=from nautae= "sailors"}}

{{term|term=maritima|content={{lang|la|maritima}}}}

{{defn|defn=}}

{{term|term=praetoria|content={{lang|la|praetoria}}}}

{{defn|defn=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}}

{{term|term=singularium|content={{lang|la|singularium}}}}

{{defn|defn={{lang|la|ala}} formed around members of the elite {{lang|la|equites singulares Augusti}} (imperial horseguards), left behind to reinforce frontier at the end of an imperial campaign}}

{{term|term=contariorum|content={{lang|la|contariorum}}}}

{{defn|defn=specialised regiment of lancers ({{lang|la|contarii}}) from {{lang|la|contus}} (a long lance)}}

{{term|term=dromedariorum|content={{lang|la|dromedariorum}}}}

{{defn|defn=specialised regiment of camel-mounted troops for desert warfare}}

{{glossary end}}

Some regiment names included additional descriptors:

{{glossary|style=padding-left:1.6em}}

{{term|term=civium Romanorum|content={{lang|la|civium Romanorum}} (c.R.)}}

{{defn|defn="of Roman citizens", honorific title awarded by the emperor to a regiment for valour. All current (but not future) members would be granted Roman citizenship, and the regiment would retain the title in perpetuity.}}

{{term|term=pia fidelis|content={{lang|la|pia fidelis}} (p.f.)}}

{{defn|defn=}}

{{term|term=veterana|content={{lang|la|veterana}}}}

{{defn|defn=uncertain meaning which may have been used to distinguish older unit from a newer unit with the same serial number and name}}

{{term|term=tironum|content={{lang|la|tironum}}}}

{{defn|defn=from {{lang|la|tirones}} ("trainees")}}

{{glossary end}}

• Auxilia
• List of Roman legions

{{notelist}}

{{reflist}}

• {{cite journal

|publisher=Blackwell Publishing|journal=Bulletin of the Institute of Classical Studies|issn=2041-5370|volume=46|issue=S81|year=2003|last=Holder|first=Paul|title=Auxiliary deployment in the reign of Hadrian|pages=101–145|doi=10.1111/j.2041-5370.2003.tb01979.x

}}

• {{cite book|location=Oxford|publisher=Archaeopress|series=BAR, International series|volume=841|last=Spaul|first=John E. H.|title=Cohors² : the evidence for and a short history of the auxiliary infantry units of the Imperial Roman army|year=2000|isbn=9781841710464

}}

• {{cite book|location=Andover|publisher=Nectoreca Press|last1=Spaul|first1=John E. H.|last2=Cichorius|first2=Conrad|title=Ala² : the auxiliary cavalry units of the pre-Diocletianic imperial Roman army|year=1994|isbn=9780952506201

}}

• [http://bbs.keyhole.com/ubb/ubbthreads.php?ubb=download&Number=977551&filename=Roman%20castra%20from%20Romania.kmz Roman auxiliary regiments from Dacia (KML file)] {{Webarchive|url=https://web.archive.org/web/20120120084233/http://bbs.keyhole.com/ubb/ubbthreads.php?ubb=download&Number=977551&filename=Roman%20castra%20from%20Romania.kmz |date=2012-01-20 }}

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