Auxilia: Wikis


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Roman auxiliary infantry crossing a river, probably the Danube, on a pontoon bridge during the emperor Trajan 's Dacian Wars (101–106 AD). They can be distinguished by the oval shield (clipeus) they were equipped with, in contrast to the rectangular scutum carried by legionaries. Panel from Trajan's Column, Rome

Auxiliaries (from Latin: auxilia = "supports") formed the standing non-citizen corps of the Roman army of the Principate (30 BC–284 AD), alongside the citizen legions. By the 2nd century, the auxilia contained the same number of infantry as the legions and in addition provided almost all the Roman army's cavalry and more specialised troops (especially light cavalry and archers). The auxilia thus represented three-fifths of Rome's regular land forces at that time. Like their legionary counterparts, auxiliary recruits were mostly volunteers, not conscripts.

Auxiliary troops were mainly recruited from the peregrini, i.e. free provincial subjects of the Roman Empire who did not hold Roman citizenship and constituted the vast majority of the empire's population in the 1st and 2nd centuries (ca. 90% in the early 1st century). Auxiliaries also included some Roman citizens and probably barbarians (barbari, as the Romans called peoples located outside the Empire's borders). This was in contrast to the legions, which admitted Roman citizens only.

The auxilia developed from the varied contingents of non-Italian troops, especially cavalry, that the Roman Republic used in increasing numbers to support its legions after 200 BC. The Julio-Claudian period (30 BC–68 AD) saw the transformation of these motley temporary levies into a standing corps of regiments with standardised structure, equipment and conditions of service. By the end of this period, there were no significant differences between legionaries and most auxiliaries in terms of training, or thus combat capability.

Auxiliary regiments were often stationed in provinces other than the province in which they were originally raised, both for reasons of imperial security and to foster the process of Romanisation and integration of the provinces. The regimental names of many auxiliary units persisted into the 4th century, but by then the units in question were different in size, structure, and quality from their predecessors.


Historical development


Background: Roman Republic (to 30 BC)

The mainstay of the Roman republic's war machine was the manipular legion, a heavy infantry unit suitable for close-quarter engagements on more or less any terrain, which was probably adopted sometime during the Samnite Wars (343–290 BC).[1] Despite its formidable strength, the legion had a number of deficiencies, especially a lack of cavalry. Around 200 BC, a legion of 4,200 infantry had a cavalry arm of only 300 horse (just 7% of the total force).[2] This was because the class of citizens who could afford to pay for their own horse and equipment – the equestrian order, the second rank in Roman society, after the senatorial order – was relatively small. In addition the legion lacked missile forces such as slingers and archers.[3] Until 200 BC, the bulk of a Roman army's cavalry was provided by Rome's regular Italian allies (socii), commonly known as the "Latin" allies, which made up the Roman military confederation. This was Rome's defence system until the Social War of 91–88 BC. The Italian forces were organised into alae (literally: "wings", because they were generally posted on the flanks of the Roman line of battle). An allied ala, commanded by 3 Roman praefecti sociorum, was similar or slightly larger in infantry size (4–5,000 men) to a legion, but contained a more substantial cavalry contingent: 900 horse, three times the legionary contingent. Since a pre-Social War consular army always contained an equal number of legions and alae, 75% of its cavalry was provided by the Latin allies. The overall cavalry element, ca. 12% of the total force (2,400 out of a normal consular army of ca. 20,000 total effectives), was greater than in most peninsular Italian forces, but well below the overall 21% cavalry component that was typical of the Principate army (80,000 cavalry out of 380,000 total effectives in early the 2nd century).[4][5]

The Roman/Latin cavalry was sufficient while Rome was in conflict with other states in the mountainous Italian peninsula, which also disposed of limited cavalry resources. But as Rome was confronted by external enemies that deployed far more powerful cavalry elements, such as the Gauls and the Carthaginians, the Roman deficiency in cavalry numbers could be a serious liability, which in the Second Punic War (218–202 BC) resulted in crushing defeats. Hannibal's major victories at the Trebia and at Cannae, were owed to his Spanish and Gallic heavy cavalry, which far outnumbered the Roman and Latin levies, and to his Numidians, light, fast cavalry which the Romans wholly lacked.[6] The decisive Roman victory at Zama in 202 BC, which ended the war, owed much to the Numidian cavalry provided by king Massinissa, which outnumbered the Roman/Latin cavalry fielded by 2 to 1.[7] From then, Roman armies were always accompanied by large numbers of non-Italian cavalry: Numidian light cavalry and, later, Gallic heavy cavalry. For example, Caesar relied heavily on Gallic and German cavalry for his Conquest of Gaul (58–51 BC).[8]

As the role of native cavalry grew, that of Roman/Latin cavalry diminished. In the early 1st century BC, Roman cavalry was phased out altogether. After the Social War, the socii were all granted Roman citizenship, the Latin alae abolished, and the socii recruited into the legions.[9] Furthermore, Roman equestrians were no longer required to perform cavalry service after this time.[10] The late Republican legion was thus probably bereft of cavalry (a tiny cavalry force of 120 men was probably added back to the legion under Augustus).[11]

By the outbreak of the Second Punic War, the Romans were remedying the legion's other deficiencies by using non-Italian specialised troops. Livy reports Hiero of Syracuse offering to supply Rome with archers and slingers in 217 BC.[12] From 200 BC onwards, specialist troops were hired as mercenaries on a regular basis: sagittarii (archers) from Crete, and funditores (slingers) from the Balearic Isles almost always accompanied Roman legions in campaigns all over the Mediterranean.[13]

The main other sources of non-Italian troops in the late Republic were subject provincials, allied cities and Rome's amici (satellite kings). During the late Republic, non-Italian units were led by their own native chiefs, and their internal organisation was left to their own commanders. The units varied widely in dress, equipment, and weapons. They were normally raised for specific campaigns and often disbanded soon afterwards, in a similar manner to the earlier socii militia legions.[14]

Foundation of the auxilia under Augustus (30 BC–14 AD)

At the end of the civil war period (31 BC), it appears that not all indigenous units were disbanded. Some of the more experienced units were kept in being to complement the legions, and became the core of the standing auxiliary forces that developed in the Julio-Claudian period.[15] During the early rule of Augustus (27 BC onwards), the corps of regular auxilia was created. It was clearly inspired by the Latin forces of the pre-Social War Republic, as a corps of non-citizen troops parallel to the legions. But there were fundamental differences, the same as between Republican and Augustan legions. The Latin forces of the Republic were made up of part-time conscripts in units that would be raised and disbanded for and after particular campaigns. The Augustan auxilia were mainly volunteer professionals serving in permanent units.[8]

The unit structure of the auxilia also differed from the Latin alae, which were like legions with a larger cavalry arm. Augustus however organised the auxilia into regiments the size of cohorts (a tenth the size of legions), due to the much greater flexibility of the smaller unit size. Further, the regiments were of three types: ala (cavalry), cohors (peditata) (infantry) and cohors equitata (mixed cavalry/infantry).[16]

The evidence for the size of the Augustus' new units is not clearcut, with our most precise evidence dating to the 2nd century, by which time the unit strengths may have changed. Cohortes were likely modelled on legionary cohorts i.e. six centuriae of about 80 men each (total about 480 men).[17] Alae were divided into turmae (squadrons) of 30 (or 32) men, each under a decurio (literally: "leader of ten").[18] This title which derives from the old Roman cavalry of the pre-Social War republic, in which each turma was under the command of three decuriones).[19] Cohortes equitatae were simply infantry cohortes with a cavalry contingent of four turmae added.[20]

Auxiliary regiments were now led by one praefectus (prefect), who could be either a native nobleman, who would probably be granted Roman citizenship for the purpose (e.g. the famous German war leader Arminius gained Roman citizenship probably by serving as an auxiliary prefect before turning against Rome); or a Roman, either of equestrian rank, or a senior centurion.[21]

At the start of Augustus' sole rule (30 BC), the original core auxiliary units in the West were composed of warlike tribesmen from the Gallic provinces (especially Gallia Belgica, which then included the regions later separated to form the provinces Germania Inferior and Germania Superior), and from the Illyrian provinces (Dalmatia and Illyricum). By 19 BC, the Cantabrian and Asturian Wars were concluded, leading to the annexation of northern Hispania and Lusitania. Judging by the names of attested auxiliary regiments, these parts of the Iberian peninsula soon became a major source of recruits. Then the Danubian regions were annexed: Raetia (annexed 15 BC), Noricum (16 BC), Pannonia (9 BC) and Moesia (6 AD), becoming, with Illyricum, the Principate's most important source of auxiliary recruits for its entire duration. In the East, where the Syrians already provided the bulk of the Roman army's archers, Augustus annexed Galatia (25 BC) and Judaea: the former, a region in central Anatolia with a Celtic-speaking people, became an important source of recruits. In N. Africa, Egypt, Cyrene, and Numidia (25 BC) were added to the empire. Numidia (modern day Eastern Algeria) was home to the Mauri, the ancestors of today's Berber people. Their light cavalry (equites Maurorum) was highly prized and had alternately fought and assisted the Romans for well over two centuries: they now started to be recruited into the regular auxilia. Even more Mauri units were formed after the annexation of Mauretania (NW Algeria, Morocco), the rest of the Berber homeland, in 44 AD by emperor Claudius (ruled 41–54).[22]

Recruitment was thus heavy throughout the Augustan period, with a steady increase in the number of units formed. By 23 AD, the Roman historian Tacitus records that there were roughly the same numbers of auxiliaries in service as there were legionaries.[23] Since at this time there were 25 legions of ca. 5,000 men each, the auxilia thus amounted to ca. 125,000 men, implying ca. 250 auxiliary regiments.[24]

Illyrian revolt (6–9 AD)

During the early Julio-Claudian period, many auxiliary regiments raised in frontier provinces were stationed in or near their home provinces, except during periods of major crises such as the Cantabrian Wars, when they were deployed temporarily in theatre. This carried the obvious risk if their own tribe or ethnic group rebelled against Rome (or attacked the Roman frontier from outside the Empire), auxiliary troops could be tempted to make common cause with them. The Romans would then be faced by an enemy that included units fully equipped and trained by themselves, thus losing their usual tactical advantages over tribal foes.[25]

Arminius is the classic example at an individual level: after several years of serving in Rome's forces as prefect of an auxiliary unit, he used the military training and experience he had gained to lead a confederacy of German tribes against Rome, culminating in the destruction of three Roman legions in the Teutoberg Forest in 9 AD, and the abandonment of Augustus' strategy of annexing Germany as far as the Elbe river. (This strategy was never revived by later emperors).[26]

At a collective level, the risk was even greater, as the hugely dangerous Illyrian revolt proved. The central Illyrian tribes were tough and spartan shepherds of the Bosnian mountains and excellent soldier-material. Their territory formed part of the strategic province of Illyricum, recently expanded to include the territory of the Pannonii, an Illyrian tribe based on the west bank of the Danube who were subjugated by Rome in 12–9 BC. By the start of the Common Era, they were an important recruitment base for the auxilia.[27] But discontent was festering among the Illyrian tribes due to what they saw as the rapacity of Roman tax officials.[28] In 6 AD, several regiments of Dalmatae, a warlike Illyrian tribe, were ordered to gather in one place to prepare to join Augustus' stepson and senior military commander Tiberius in a war against the Germans. Instead they mutinied at the assembly point, and defeated a Roman force sent against them.[29] The Dalmatae were soon joined by the Breuci, another Illyrian tribe that supplied several auxiliary regiments. They gave battle to a second Roman force from Moesia. They lost, but inflicted heavy casualties.[30] The rebels were now joined by a large number of other Illyrian tribes. The Dalmatae attacked Salona and overran the Adriatic coast, defeating a Roman force and exposing the Roman heartland of Italy to the fear of a rebel invasion.[31]

Augustus ordered Tiberius to break off operations in Germany and move his main army to Illyricum.[32] When it became clear that even Tiberius' forces were insufficient, Augustus was obliged to raise a second task force under Tiberius' nephew Germanicus, resorting to the compulsory purchase and emancipation of thousands of slaves to find enough troops, for the first time since the aftermath of the Battle of Cannae two centuries earlier.[33] The Romans had now deployed no less than 15 legions and an equivalent number of auxilia.[34] This amounts to a total of ca. 150,000 men, including at least 50 auxiliary cohorts composed, exceptionally, of Roman citizens. These were men whose status or background was regarded by Augustus as unsuitable for recruitment into the legions: either natural-born citizens of the lowest category including vagrants and convicted criminals, or the freed slaves (Roman law accorded citizenship to the freed slaves of Roman citizens). These special units were accorded the title civium Romanorum ("of Roman citizens"), or c.R. for short. After the Illyrian revolt, these cohorts remained in being and recruited non-citizens like other auxiliary units, but retained their prestigious c.R. title.[16][35] In addition, the regular forces were assisted by a large number of allied troops from neighbouring Thrace deployed by their king Rhoemetalces I, a Roman amicus (puppet king).[36]

The Romans faced further reverses on the battlefield and a savage guerrilla war in the Bosnian mountains.[37] It took them three years of hard fighting to quell the revolt, which was described by the Roman historian Suetonius as the most difficult conflict faced by Rome since the Punic Wars two centuries earlier.[34] Tiberius finally succeeded in quelling the revolt in 9 AD. This was just in time: that same year Arminius destroyed Varus' three legions in Germany. The Roman high command was in no doubt that Arminius would have formed a grand alliance with the Illyrians.[38]

Despite the gravity of this rebellion, the Illyrians went on to become the backbone of the Roman army. By the 2nd century, with roughly half the Roman army deployed on the Danube frontier, the auxilia and legions alike were dominated by Illyrian recruits. In the 3rd century, Illyrians largely replaced Italians in the senior officer echelons of praefecti of auxiliary regiments and tribuni militum of legions. Finally, from 268 to 379 AD, virtually all emperors, including Diocletian and Constantine the Great were Romanised Illyrians from the provinces of Dalmatia, Moesia Superior and Pannonia. These were members of a military aristocracy, outstanding soldiers who saved the empire from collapse in the turbulent late 3rd century.[39]

Later Julio-Claudians (14–68 AD)

Significant development of the auxilia appears to have taken place during the rule of the emperor Claudius (41–54 AD). A minimum term of service of 25 years was established, at the end of which the retiring auxiliary soldier, and all his children, were awarded Roman citizenship.[40] This is deduced from the fact that the first known Roman military diplomas date from the time of Claudius. This was a folding bronze tablet engraved with the details of the soldier's service record, which he could use to prove his citizenship.[41] Claudius also decreed that prefects of auxiliary regiments must all be of equestrian rank, thus excluding centurions from such commands.[40] The fact that auxiliary commanders were now all of the same social rank as most tribuni militum, (military tribunes, a legion's senior staff officers, all of whom only one, the tribunus laticlavius, was of the higher senatorial rank), probably indicates that auxilia now enjoyed greater prestige. Indigenous chiefs continued to command some auxiliary regiments, and were probably granted equestrian rank for the purpose. It is also likely that auxiliary pay was standardised at this time, but we only have estimates for the Julio-Claudian period.[40]

Auxiliary uniform, armour, weapons and equipment were probably standardised by the end of the Julio-Claudian period. Auxiliary equipment was broadly similar to that of the legions (see Section 2.1 below for possible differences in armour). By 68 AD, there was little difference between most auxiliary infantry and their legionary counterparts in equipment, training and fighting capability. The main difference was that auxilia contained combat cavalry, both heavy and light, and other specialised units that legions lacked.[42]

Claudius annexed to the empire three regions that became important sources of auxiliary recruits: Britannia (43 AD), and the client kingdoms of Mauretania (44) and Thracia (46). The latter became as important as Illyria as a source of auxiliary recruits, especially cavalry and archers. Britain in mid-2nd century contained the largest number of auxiliary regiments in any single province: about 60 out of about 400 (15%).[4] By the rule of Nero (54–68), auxiliary numbers may have reached, by one estimate, about 200,000 men, implying about 400 regiments.[40]

Revolt of the Batavi (69–70 AD)

Rhine frontier of the Roman empire, 70 AD, showing the location of the Batavi in the Rhine delta region. Roman territory is shaded dark. Their homeland was called the Insula Batavorum by the Romans and corresponded roughly with modern Gelderland province, Neth. Their chief town was Noviomagus (Nijmegen, Neth.), a strategic prominence in an otherwise flat and waterlogged land that became the site of a Roman legionary fortress (housing the legion X Gemina) after the Batavi revolt ended in 70 AD. The name is of Celtic origin, meaning "new market", suggesting that the Germanic Batavi either displaced or subjugated an indigenous Gallic tribe

The Batavi, a Germanic tribe, inhabited the region today known as Gelderland (Netherlands), in the Rhine river delta, then known as the Insula Batavorum ("Island of the Batavi", because surrounded by branches of the Rhine), part of the Roman province of Germania Inferior.[43] They were a warlike people, skilled horsemen, boatmen and swimmers. In return for the unusual privilege of exemption from tributum (direct taxes on land and heads normally exacted from peregrini), they supplied a disproportionate number of recruits to the Julio-Claudian auxilia: one ala and eight cohortes.[44] They also provided most of Augustus' elite personal bodyguard unit (the Germani corpore custodes), which continued in service until 68 AD. The Batavi auxilia amounted to about 5,000 men, implying that during the entire Julio-Claudian period, over 50% of all Batavi males reaching military age (16 years) may have enlisted in the auxilia.[45] Thus the Batavi, although just 0.05% of the total population of the empire of ca. 70 million in 23 AD,[46] supplied about 4% of the total auxilia i.e. 80 times their proportionate share. They were regarded by the Romans as the very best (fortissimi, validissimi) of their auxiliary, and indeed all, their forces.[47] In Roman service, both their cavalry and infantry had perfected a technique for swimming across rivers wearing full armour and weapons.[48][49]

Julius Civilis (literally: "Julius the Citizen", clearly a Latin name adopted on gaining Roman citizenship, not his native one) was a hereditary prince of the Batavi and the prefect of a Batavi cohort. A veteran of 25 years' service, he had distinguished himself by service in Britain, where he and the eight Batavi cohorts had played a crucial role in both the Roman invasion in 43 AD and the subsequent subjugation of southern Britain.[50]

By 69, however, Civilis, the Batavi regiments and the Batavi people had become utterly disaffected with Rome. After the Batavi regiments were withdrawn from Britain to Italy in 66, Civilis and his brother (also a prefect) were arrested by the governor of Germania Inferior on a fabricated accusation of sedition. The governor ordered his brother's execution, while Civilis, who as a Roman citizen had the right to appeal to the emperor, was sent to Rome in chains for judgement by Nero.[51] He was released by Nero's overthrower and successor, Galba, but the latter also disbanded the imperial bodyguard unit for their loyalty to Nero. This alienated several hundred crack Batavi troops, and indeed the whole Batavi nation who regarded it as a grave insult.[52] At the same time, relations collapsed between the Batavi cohorts and the legion to which they had been attached since the invasion of Britain 25 years earlier (XIV Gemina). Their mutual hatred erupted in open fighting on at least two occasions.[53]

At this juncture, the Roman empire was convulsed by its first major civil war since the Battle of Actium exactly a century earlier: the Year of the Four Emperors (69-70 AD). The governor of Germania Inferior, ordered to raise more troops, outraged the Batavi by attempting to conscript more Batavi than the maximum stipulated in their treaty. The brutality and corruption of the Roman recruiting-centurions (including incidents of sexual assault on Batavi young men) brought already deep discontent in the Batavi homeland to the boil.[54]

Civilis now led his people in open revolt. Initially, he claimed he was supporting the bid for power of Vespasian, the general in command of the legions in Syria, whom Civilis had probably befriended when both were involved in the Roman invasion 25 years before (Vespasian was then commander of the legion II Augusta).[55] But the uprising soon became a bid for independence.[56] Civilis exploited the fact that some legions were absent from the Rhine area due to the civil war, and the rest under-strength. In addition, the Roman commanders and their rank-and-file soldiers were divided by loyalty to rival emperors.[57] Civilis quickly won the support of the Batavi's neighbours and kinsmen, the Cananefates, who in turn won over the Frisii. First the rebel allies captured two Roman forts in their territory, and a cohort of Tungri defected to Civilis.[58] Then two legions sent against Civilis were defeated when their companion Batavi ala defected to his side.[43] The Classis Germanica (Rhine flotilla), largely manned by Batavi, was seized by Civilis.[59] Most importantly, the eight Batavi cohorts stationed at Mainz with XIV Gemina mutinied and joined him, defeating at Bonn a Roman force that attempted to block their return to their homeland.[60] By now, Civilis commanded at least 12 regiments (6,000 men) of Roman-trained and equipped auxiliary troops, as well as a much larger number of tribal levies. A number of German tribes from beyond the Rhine joined his cause.[61] Several other German and Gallic units sent against him deserted, as the revolt spread to the rest of Gallia Belgica, including the Tungri, Lingones and Treviri tribes.[62] He was able to destroy the two remaining legions in Germania Inferior, (V Alaudae and XV Primigenia).[63]

By this stage Rome's entire position on the Rhine and even in Gaul was imperiled. Their civil war over, the Romans mustered a huge task force of eight legions (five dispatched from Italy, two from Spain and one from Britain) to deal with Civilis.[64] Its commander Petillius Cerialis had to fight two difficult battles, at Trier and Xanten, before he could overrun the Batavi's homeland.[65] Tacitus' surviving narrative breaks off as he describes a meeting on an island in the Rhine delta between Civilis and Cerialis to discuss peace terms.[66] We do not know the outcome of this meeting or Civilis' ultimate fate. But in view of his former friendship with Vespasian, who had already offered him a pardon, and the fact that the Romans still needed the Batavi levies, it is likely that the terms were lenient by Roman standards.[67]

Petilius Cerialis took a number of reconstituted Batavi units with him to Britain, and the Batavi regiments continued to serve with special distinction in Britain and elsewhere for the rest of the 1st century and beyond.[68] Even as late as 395, units with the Batavi name, although long since composed of recruits from all over the empire, were still classified as elite palatini, e.g. the equites Batavi seniores (cavalry) and auxilium Batavi seniores (infantry).[69]

Flavian era (69–96 AD)

Tombstone of the Flavian-era eques (cavalryman) Titus Flavius Bassus, son of Mucala. A Dansala, (i.e. member of the Thracian Dentheletae tribe), he belonged to the Ala Noricorum (originally raised from the Taurisci tribe of Noricum). He died at age 46 after 26 years' service, not having advanced beyond the lowest rank. Bassus' adopted Roman names, Titus Flavius, indicate that he had gained Roman citizenship, doubtless by serving the required 25 years in the auxilia. The names adopted would normally be those of the emperor ruling at the time of the citizenship award. In this case, they could refer to any of the 3 emperors of the Flavian dynasty (ruled 69-96), Vespasian and his two sons, Titus and Domitian, all of whom carried the same names. The arrangement of the scene, a rider spearing a man (the motif of the Thracian Hero), indicates that Bassus was a Thracian. Date: Late 1st century. Römisch-Germanisches Museum, Cologne, Germany

The revolt of the Batavi appears to have led to a significant change in the Roman government's policy on auxiliary deployment. The revolt proved that in times of civil strife, when legions were far from their bases campaigning for rival claimants to the imperial throne, it was dangerous to leave provinces exclusively in the hands of auxiliary regiments recruited from the indigenous nation. During the Julio-Claudian period, auxiliary regiments had often been deployed away from their original home province.[8] But in the Flavian period (69–96), this appears to have become standard policy.[25] Thus in 70 AD five reconstituted Batavi regiments (one ala and four cohortes) were transferred to Britain under Petillius Cerialis, who had suppressed the Civilis revolt and then embarked on the governorship of the island.[70] The great majority of regiments probably founded in the first century were stationed away from their province of origin in the second e.g. of 13 British regiments recorded in mid 2nd century, none were stationed in Britain.[71] Furthermore, it appears that in the Flavian era native nobles were no longer permitted to command auxiliary units from their own nation.[72]

After a prolonged period in a foreign province a regiment would become assimilated, since the majority of its new recruits would be drawn from the province in which it was stationed, or neighbouring provinces.[25] Those same "British" units, mostly based on the Danube frontier, would by ca. 150, after almost a century away from their home island, be largely composed of Illyrian, Thracian and Dacian recruits. However, there is evidence that a few regiments at least continued to draw some recruits from their original home provinces in the 2nd century e.g. Batavi units stationed in Britain.[73 ]

The Flavian period also saw the first formation of large, double-size units, both infantry and cavalry, of a nominal strength of 1,000 men (cohors/ala milliaria), though they were actually mostly smaller (720 for an ala milliaria and 800 for a cohors milliaria).[40] These were the mirror image of the double-strength first cohorts of legions also introduced at this time. Such units remained a minority of the auxilia: in mid-2nd century, they constituted 13% of units, containing 20% of total manpower.[74]

Later Principate (97–284)

Roman cavalry spatha, a longer sword (median blade length: 780 mm [30.7 in]), designed to give the rider a longer reach than the gladius[75]

In 106 AD, emperor Trajan finally defeated the Dacian kingdom of Decebalus and annexed it as the Roman province of Dacia Traiana. By mid 2nd century, there were 44 auxiliary regiments stationed there, about 10% of the total auxilia. In Britain there were 60. Together these two provinces contained about a quarter of the total auxiliary regiments.[4]

There is some discrepancy about the precise size of the auxilia during the rule of Trajan's successor, Hadrian (117-138) between the two most up-to-date global analyses of the Roman auxilia, by Spaul (2000) and Holder (2003)

Author No. Alae No. Cohortes Total no. units Total cavalry Total infantry Total effectives
J. Spaul (2000)[76] 80 247 327 56,160 124,640 180,800
P. A. Holder (2003)[77] 88 279 367 74,624 143,200 217,624

NOTE: Manpower figures exclude officers (centurions and decurions), which would have numbered ca. 3,500 men overall.

In addition, Holder believes that a further 14 cohortes, which are attested under Trajan, immediately before Hadrian's rule, but not during or after it, were probably in existence at this time, giving a total of 381 units and 225,000 effectives. The discrepancy between the two scholars is due to: (i) Interpretation of units with the same name and number, but attested in different provinces in the same period. Spaul tends to take a more cautious approach and to assume such are the same unit moving base frequently, while Holder tends to regard them as separate units which acquired the same number due to double (or triple) seriation. (ii) Assumptions about how many cohortes were equitatae. Spaul accepts only those cohortes specifically attested as equitatae i.e. ca. 40% of recorded units. Holder estimates that at least 70% of cohortes contained cavalry contingents by the early 2nd century[78]

Even according to the more conservative estimate, the auxilia were by this time significantly larger than the legions, which contained ca. 155,000 effectives (28 legions of 5,500 men each) at this time, of which just 3,360 were cavalry. (For a detailed breakdown, see section 4: Auxilia deployment in the 2nd century, below).

During the second half of the 2nd century, the Roman army underwent considerable further expansion, with the addition of 5 new legions (27,500 men) to a peak of 33.[79] An equivalent number of auxilia (i.e. 50–60 new regiments) were probably added, perhaps reaching a peak of ca. 440 regiments and over 250,000 effectives by the end of Septimius Severus's rule (211 AD).[5]

The likely growth of the Roman auxilia may be summarised as follows:

Army corps Tiberius
24 AD
ca. 130 AD
S. Severus
211 AD
3rd c. crisis
ca. 270 AD
LEGIONS 125,000[80] 155,000[81] 182,000[82]
AUXILIA 125,000[83] 218,000[84] 250,000[85]
PRAETORIAN GUARD ~~5,000[86] ~10,000[87] ~10,000
Total Roman Army 255,000[88] 383,000[89] 442,000[90] 290,000?[91] 390,000[92]

NOTE: Figures are based on official (not actual) unit strengths and exclude Roman Navy effectives and barbarian foederati.

During the 2nd century some units with the new names numerus ("group") and vexillatio ("detachment") appear in the diploma record.[93] Their size is uncertain, but was likely smaller than the regular alae and cohortes, as originally they were probably detachments from the latter, acquiring independent status after long-term separation. As these units are mentioned in diplomas, they were presumably part of the regular auxiliary organisation.[94] But numeri was also a generic term used for barbarian units outside the regular auxilia. (see section 2.4 Irregular units, below).

In 212, the constitutio Antoniniana (Antonine decree) of emperor Caracalla granted Roman citizenship to all the free inhabitants of the Empire – the peregrini – thus abolishing their second-class status.[95] But there is no evidence that the citizens-only rule for legions was also abolished at this time. The legions simply gained a much wider recruitment base, as they were now able to recruit any male free resident of the empire. Auxiliary units were now recruited mainly from Roman citizens, but probably continued to recruit non-citizen barbari from outside the Empire's borders.[96] However, the citizens-only rule for legions appears to have been dropped some time during the 3rd century, as by the 4th century Romans and barbarians are found serving together in all units.[97 ]

In the mid to late 3rd century, the army was afflicted by a combination of military disasters and of pestilence, the so-called Crisis of the Third Century. In 251–271 Gaul, the Alpine regions and Italy, the Balkans and the East were simultaneously overrun by Alamanni, Sarmatians, Goths and Persians respectively.[98] At the same time, the Roman army was struggling with the effects of a devastating pandemic, probably of smallpox: the Plague of Cyprian which began in 251 and was still raging in 270, when it claimed the life of emperor Claudius II Gothicus. The evidence for an earlier pandemic, the Antonine Plague (also smallpox) indicates a mortality of 15–30% in the empire as a whole.[99] The armies would likely have suffered deaths at the top end of the range, due to their close concentration of individuals and frequent movements across the empire.[100] This probably led to a steep decline in military numbers, which only recovered at the end of the century under Diocletian (r. 284–305).[101]

The recruitment shortfall caused by the crisis seems to have led to recruitment of barbarians to the auxilia on a much greater scale than previously. By the 4th century, it has been estimated that some 25% of regular army recruits were barbarian-born. In the elite palatini regiments anywhere between a third and a half of recruits may have been barbarian.[97 ] This is likely a much greater proportion of foreigners than joined the auxilia in the 1st-2nd centuries.[102] In the 3rd century, a small number of regular auxiliary units appear in the record that, for the first time, bear the names of barbarian tribes from outside the empire e.g. the ala I Sarmatarum attested in 3rd-century Britain.[103] This was probably an offshoot of the 5,500 surrendered Sarmatian horsemen posted on Hadrian's Wall by emperor Marcus Aurelius in ca. 175.[104] This unit may be an early example of a novel process whereby irregular units of barbari (foederati) were transformed into regular auxilia. This process intensified in the 4th century: the Notitia Dignitatum, a key document on the late Roman army, lists a large number of regular units with barbarian names.[105]

Fourth century

In the fourth century, the Roman army underwent a radical restructuring. In the rule of Diocletian (284–305), the traditional Principate formations of legiones, alae and cohortes appear to have been broken up into smaller units, many of which bore a variety of new names.[106] Under Constantine I (r. 312–337) it appears that military units were classified into three grades based on strategic role and to some extent quality: palatini, elite units normally part of the exercitus praesentales (imperial escort armies); comitatenses, higher-grade interception forces based in frontier provinces; and limitanei, lower-grade border troops.[107] (See Late Roman army).

The old Principate auxilia regiments provided the basis for units at all three grades. The Notitia Dignitatum lists about 70 alae and cohortes that retained their 2nd century names, mostly limitanei.[108] But traces of other auxilia regiments can be found in the praesentales and comitatenses armies. For example, many of the new-style auxilia palatina infantry regiments, considered among the best units in the army, were probably formed from old-style auxiliary cohortes, which they appear to closely resemble.[109]

The late 4th century writer on military affairs Vegetius complains of contemporary young men joining the "auxilia" in preference to the "legions" to avoid the latter's tougher training and duties.[110] But it is unclear what types of units he was referring to. It is possible that those older terms were still popularly used (misleadingly) to mean limitanei and comitatenses respectively. In any event, his quote in no way describes accurately the Principate auxilia, many of which were of very high quality.[16]

Unit types and structure

Regular unit types

The following table sets out the official, or establishment, strength of auxiliary units in the 2nd century. The real strength of a unit would fluctuate continually, but would likely have been somewhat less than the establishment most of the time.

Unit type Service Unit
No of
Ala quingenaria cavalry praefectus decurio 16 turmae 30 (32) 480 (512)
Ala milliaria cavalry praefectus decurio 24 turmae 30 (32) 720 (768)
Cohors quingenaria infantry praefectus* centurio 6 centuriae 80 480
Cohors milliaria infantry tribunus militum** centurio 10 centuriae 80 800
Cohors equitata
infantry plus
cavalry contingent
praefectus centurio (inf)
decurio (cav)
6 centuriae
4 turmae
(480 inf/120 cav)
Cohors equitata
infantry plus
cavalry contingent
tribunus militum** centurio (inf)
decurio (cav)
10 centuriae
8 turmae
(800 inf/240 cav)

* tribunus militum in original c.R. cohortes[112]
** praefectus in Batavi and Tungri cohortes milliariae[112]

NOTE: Opinion is divided about the size of an ala turma, between 30 and 32 men. 30 was the size of a turma in the Republican cavalry and in the cohors equitata of the Principate auxilia. Against this is a statement by Arrian that an ala was 512 strong.[113] This would make an ala turma 32 men strong.


These all-infantry units were modelled on the cohorts of the legions, with the same officers and sub-units. It is a common misconception that auxiliary cohortes contained light infantry. Their defensive equipment was very similar to that of legionaries, consisting of metal helmet and metal cuirass (chain-mail or scale). However, there is no evidence that auxiliaries were equipped with the lorica segmentata, the elaborate and expensive laminated-strip body-armour that was issued to legionaries. But legionaries often wore chain-mail ans scalar cuirasses also. a[›] In addition, it appears that auxiliaries carried a round shield (clipeus) instead of the curved rectangular shield (scutum) of legionaries. As regards weapons, auxiliaries were equipped in the same way as legionaries: a javelin (although not the sophisticated pilum type provided to legionaries), a gladius (short stabbing-sword) and pugio (dagger).[114] It has been estimated that the total weight of auxiliary infantry equipment was similar to that of legionaries', so that cohortes may also be classified as heavy infantry, which fought in the battle-line alongside legionaries.[16]

There is no evidence that auxiliary infantry fought in a looser order than legionaries.[16] It appears that in a set-piece battle-line, auxiliary infantry would normally be stationed on the flanks, with legionary infantry holding the centre e.g. as in the Battle of Watling Street (60 AD), the final defeat of the rebel Britons under queen Boudicca.[115] This was a tradition inherited from the Republic, when the precursors of auxiliary cohortes, the Latin alae, occupied the same position in the line.[116] But the flanks of the line required equal, if not greater, skill to hold as the centre.


Reenactor as auxiliary cavalryman (eques alaris or alarius) with spatha (sword). In addition, he carries a hasta (spear) and oval shield (not visible, over his left shoulder). Note the reconstructed four-horned sella (Roman saddle). This was designed to give a firm seat, to compensate for the absence of stirrups, which were not introduced until the 6th century.[117]
Roman auxiliary troops defend a fort against attacking Dacians, during emperor Trajan's conquest of Dacia. Detail from Trajan's Column, Rome. Early 2nd century
Legionaries (centre) and auxiliaries (right) jointly assail a Dacian fort. The legionaries are shown advancing in the testudo formation. The auxiliaries storm a side-gate. Detail from Trajan's Column, Rome
Routed Sarmatian cataphracts (right) flee for their lives from Roman alares (auxiliary cavalrymen), during the Dacian Wars (AD 101-6). Note full-body scalar armour, also armoured caparison for horses (including eye-guards). The Sarmatians' lances (as well as the Romans') have disappeared due to stone erosion, but a sword is still visible, as is a bow carried by one man. It was apparently in the period following this conflict (perhaps as a result of the lessons learnt from it) that the Romans first established their own regular units of cataphracts, and deployed them in the Danubian region. They were most likely equipped as the Sarmatians. Panel from Trajan's Column, Rome
Roman archers (top left) in action. Note conical helmets, indicating Syrian unit, and recurved bows. Trajan's Column, Rome
Roman slingers (funditores) in action in the Dacian Wars. Detail from Trajan's Column, Rome

The all-mounted alae contained the elite cavalry of the Roman army.[16] They were specially trained in elaborate manoeuvres, such as those displayed to the emperor Hadrian during a documented inspection. They were best-suited for large-scale operations and battle, during which they acted as the primary cavalry escort for the legions, which had almost no cavalry of their own. They were heavily protected, with chain-mail or scale body armour, a cavalry version of the infantry helmet (with more protective features) and oval shield. Their offensive weapons included a spear (hasta), a cavalry sword (spatha), which was much longer than the infantry gladius to provide greater reach and a long dagger. The elite status of an alaris is shown by the fact that he received 20% greater pay than his counterpart in a cohort, and than a legionary infantryman.

Cohortes equitatae

These were cohortes with a cavalry contingent attached. There is evidence that their numbers expanded with the passage of time. Only ca. 40% of attested cohortes are specifically attested as equitatae in inscriptions, which is probably the original Augustan proportion. But a study of units stationed in Syria in the mid 2nd century found that many units which did not carry the equitata title did in fact contain cavalrymen e.g. by discovery of a tombstone of a cavalryman attached to the cohort. This implies that by that time, at least 70% of cohortes were probably equitatae.[78] The addition of cavalry to a cohort obviously enabled it to carry out a wider range of independent operations. A cohors equitata was in effect a self-contained mini-army.[118]

The traditional view of equites cohortales (the cavalry arm of cohortes equitatae), as expounded by G.L. Cheesman, was that they were just a mounted infantry with poor-quality horses. They would use their mounts simply to reach the combat zone and then would dismount to fight.[119] This view is today discredited. Although it is clear that equites cohortales did not match equites alares (ala cavalrymen) in quality (hence their lower pay), the evidence is that they fought as cavalry in the same way as the alares and often alongside them. Their armour and weapons were the same as for the alares.[120]

Nevertheless, non-combat roles of the equites cohortales differed significantly from the alares. Non-combat roles such as despatch-riders (dispositi) were generally filled by cohort cavalry.

Relationship with legions

The role of the standard auxiliary cohortes vis-a-vis legionary infantry has often been misunderstood. One common view is that legionaries were higher-quality troops than auxiliaries. The main evidence used to support this view is that legionaries were paid a higher salary. Outdated scholars suggest that auxiliary pay was as little as one-third of the legionary level. But more recent studies have concluded that the differential was much smaller (just 20% less) and in any case only applied to infantry. Equites cohortales (cohort cavalry) were paid the same as legionaries, and equites alares (ala cavalry) about 20% more.[121] The legionary's higher pay and valuable bonuses are probably due more to his social superiority as a Roman citizen than to any higher military proficiency. Tacitus' account of the clashes between Batavi auxiliaries and Roman legionaries during the revolt of the Batavi shows that there was no appreciable difference in quality between them.[122]

An auxiliary regiment would normally, but not always, be attached to a legion for operational purposes, with the praefectus under the command of the legatus legionis (the legion's commander). The period that it was so attached could be a long one e.g. the eight Batavi cohortes apparently attached to legion XIV Gemina for the 26 years from the invasion of Britain in 43 AD to the Civil War of 69.[123] But a legion had no standard, permanent complement of auxilia.[16] Its attached auxiliary units were changed and varied in number according to operational requirements at the behest of the legatus Augusti pro praetore (the governor of the province where the legion was based at the time) or of the emperor in Rome.[124]

The fact that auxiliary regiments were attached to a legion does not imply that they were not capable of, or were not permitted to, carry out operations unaccompanied. Auxiliary regiments were designed as independent formations.[16] Indeed, in view of their lack of significant cavalry or archers, it was the legions which could not easily campaign independently. Examples of major operations carried out by auxilia alone is the campaign against the Iceni tribe in Britain under governor Ostorius Scapula in 47, and the rescue of Brigantian queen Cartimandua in 52.[125] On Trajan's Column, some 20 major battle scenes are shown. Auxilia take part in 19 of these, in 12 of which they are fighting alone, unaccompanied by legionaries.[126]

It has been suggested that the auxilia acted as a border defence force, similar to the limitanei troops of the Late Roman army, while the legions acted as a strategic reserve, charged with intercepting major barbarian incursions that the auxilia could not deal with alone. The evidence for this is mixed. In some provinces, e.g. Britain, legionary bases were well behind the frontline. In Britain, the legionary fortresses of Chester and York were over 100 kilometres (62 mi) from Hadrian's Wall. But in other provinces, legions were stationed right on the border: e.g. Regensburg, Vienna and Budapest on the Danube.[127] In Britain, the main responsibility for garrisoning the forts on the Wall and beyond lay with the auxilia. But there is growing evidence that such forts were also garrisoned by legionary detachments, and even by mixed legionary/auxiliary garrisons[128]

Specialised units

In the Republican period, the standard trio of specialised auxilia were Balearic slingers, Cretan archers and Numidian light cavalry. These functions continued in the 2nd century auxilia, plus a few new ones:

Heavily-armoured lancers

Equites cataphractarii, or simply cataphractarii for short, were the heavily-armoured cavalry of the Roman army.Based on Sarmatian and Parthian models, they were also known as contarii and clibanarii, although it is unclear whether these terms were interchangeable or whether they denoted variations in equipment or role. Together with new units of light mounted archers, the cataphractarii were designed to counter Parthian (and, in Pannonia, Sarmatian) battle tactics. Parthian armies consisted largely of cavalry. Their standard tactic was to use light mounted archers to weaken and break up the Roman infantry line, and then to rout it witth a charge by the cataphractarii concentrated on the weakest point.[129] The only special heavy cavalry units to appear in the 2nd century record are: ala I Ulpia contariorum and ala I Gallorum et Pannoniorum cataphractaria stationed in Pannonia and Moesia Inferior respectively in the 2nd century.[130]

Light cavalry

From the Second Punic War until the 3rd century AD, the bulk of Rome's light cavalry (apart from mounted archers from Syria) was provided by the inhabitants of the northwest African provinces of Africa proconsularis and Mauretania, the Numidae or Mauri (from whom derives the English term "Moors"), who were the ancestors of the Berber people of modern Algeria and Morocco. They were known as the equites Maurorum or Numidarum ("Moorish or Numidian cavalry"). On Trajan's Column, Mauri horsemen, depicted with long hair in dreadlocks, are shown riding their small but resilient horses bare-back and unbridled, with a simple braided rope round their mount's neck for control. They wear no body or head armour, carrying only a small, round leather shield. Their weaponry cannot be discerned due to stone erosion, but is known from Livy to have consisted of several short javelins.[131][132] Exceptionally fast and maneouvrable, Numidian cavalry would harass the enemy by hit-and-run attacks, riding up and loosing volleys of javelins, then scattering faster than any opposing cavalry could pursue. They were superbly suited to scouting, harassment, ambush and pursuit.[133] It is unclear what proportion of the Numidian cavalry were regular auxilia units as opposed to irregular foederati units.[134]

In the 3rd century, new formations of light cavalry appear, apparently recruited from the Danubian provinces: the equites Dalmatae ("Dalmatian cavalry"). Little is known about these, but they were prominent in the 4th century, with several units listed in the Notitia Dignitatum.

Camel troops

A unit of dromedarii ("camel-mounted troops") is attested from the 2nd century, the ala I Ulpia dromedariorum milliaria in Syria.[135]


Sagittarii ("archers", lit. "arrow-men", from sagitta = "arrow") units recorded in the 2nd century are: 8 alae sagittariorum (mounted archers), 18 cohortes sagittariorum (foot archers) and 6 cohortes sagittariorum equitatae (mixed foot/mounted archers). These 32 units (of which four were double-strength) would have comprised officially 17,600 archers. They were now predominantly of Syrian origin, just one unit, cohors I Cretum sagitt. eq., bearing the name of the Cretan archers who had traditionally served the Republic. Of the 32 sagittarii units attested in mid 2nd century, 13 have Syrian names, 7 Thracian, 5 from Asia Minor, 1 from Crete and the remaining 6 of other or uncertain origin.[136]

Three distinct types of archers are shown on Trajan's Column: (a) with scalar cuirass, conical steel helmet and cloak; (b) without armour, cloth conical cap, and long vest; (c) equipped in the same way as general auxiliary foot soldiers. The first two types were probably Syrian units; the third type probably Thracian.[137] The standard bow used by Roman auxilia was the recurved composite bow, a sophisticated, compact and powerful weapon.[138]

It is unclear from the evidence if all sagittarii units contained only archers. Some sagittarii units were equipped in the same way as ordinary alae and cohortes, apart from carrying bows. Also, it would be surprising if ordinary units completely lacked archers, since that would limit their capacity for independent operations. Indeed, some non-sagittarii units are shown employing bows.[138]


Funditores, ("slingers", from funda = "sling") units do not appear in the epigraphic record.[138] However, slingers are portrayed on Trajan's Column. They are shown unarmoured, wearing a short tunic. They carry a cloth bag, slung in front, to hold their shot (glandes).[137] The late Roman army of the 4th century contained at least one independent funditores unit.[139]


Exploratores ("reconnaissance troops", from explorare = "to scout"): Examples include two numeri exploratorum attested in the 3rd century in Britain: Habitanco and Bremenio (both names of forts). Little is known about such units.[140]

Irregular units

Throughout the Principate period, there is evidence of ethnic units of barbari outside the normal auxilia organisation fighting alongside Roman troops. To an extent, these units were simply a continuation of the old client-king levies of the late Republic: ad hoc bodies of troops supplied by Rome's puppet kinglets on the imperial borders for particular campaigns. But some clearly remained in Roman service beyond the campaigns, keeping their own native leadership, attire and equipment and structure. These units were known to the Romans as socii ("allies"), symmachiarii (Greek for "allies") or foederati ("treaty troops" from foedus, "treaty"). One estimate puts the number of foederati in the time of Trajan at ca. 11,000, divided into numeri (units) of ca. 300 men each. The purpose of employing foederati units was to use their specialist fighting skills.[141] Many of these would have been troops of Numidian cavalry.(See Light cavalry above).

The foederati make their first official appearance on Trajan's Column. Here they are portrayed in a standardised manner: with long hair and beards, barefoot, stripped to the waist, wearing long trousers held up by wide belts and wielding clubs. In reality several different tribes supported the Romans in the Dacian wars. Their attire and weapons would have varied widely. The Column stereotypes them with the appearance of a single tribe, probably the most outlandish-looking, to differentiate them clearly from the regular auxilia.[142] Judging by the frequency of their appearance in the Column's battle scenes, the foederati were important contributors to the Roman operations in Dacia. Another example of foederati are the 5,500 captured Sarmatian cavalrymen sent by Emperor Marcus Aurelius (r. 161–180) to garrison a fort on Hadrian's Wall after their defeat in the Marcomannic Wars[143]

Recruitment, ranks and pay

The evidence for auxiliary ranks and pay is scant, even less than the patchy evidence for their legionary counterparts. The available data may be summarised as follows:

AUXILIA RANKS AND PAY (mid 1st century)[144]
Pay scale
(as multiple of basic)
Cohors infantry rank
(in ascending order)
XXX Ala rank
(in ascending order)
1 (caligati = "rankers") pedes (infantryman) 188 gregalis (ala cavalryman) 263
1.5 (sesquiplicarii = "one-and-half-pay men") tesserarius (corporal) 282 sesquiplicarius (corporal) 395
2 (duplicarii = "double-pay men") signifer (centuria standard-bearer)
optio (centurion's deputy)
vexillarius (cohort standard-bearer)
376 signifer (turma standard-bearer)
curator? (decurion's deputy)
vexillarius (ala standard-bearer)
Over 5 centurio (centurion = centuria commander)
centurio princeps (chief centurion)
beneficiarius? (deputy cohort commander)
940 + decurio (decurion = turma commander)
decurio princeps (chief decurion)
beneficiarius? (deputy ala commander)
1,315 +
50 praefectus or tribunus (cohort commander) 9,400 praefectus or tribunus (ala commander) 13,150

Common soldiers (caligati)

Tombstone of Marius son of Ructicnus. The inscription states that he was a miles (ranker) of the Alpine infantry regiment Cohors I Montanorum, who died in his 25th year of service (i.e. in the final year of the minimum term for an auxiliary and just before qualifying for Roman citizenship). His heir, who erected the stone, is named Montanus, the same ethnic name as the regiment's, meaning a native of the eastern Alps, most likely the origin of the deceased. Note (top corners) the Alpine edelweiss flowers, called stella Alpina ("Alpine star") in Latin. These were either a regimental symbol, or a national symbol of the Montani. The crescent moon-and-star motif between the flowers may be either a regimental emblem or a religious symbol. Date: 1st century, probably ante 68. From Carinthia, Austria

At the bottom end of the rank pyramid, rankers were known as caligati (lit: "sandal men" from the caligae or hob-nailed sandals worn by soldiers). Depending on the type of regiment they belonged to, they held the official ranks of pedes (foot soldier in a cohors), eques (cavalryman in a cohors equitata) and gregalis (ala cavalryman).[145]

During the Principate, recruitment into the legions was restricted to Roman citizens only. This rule, which derived from the pre-Social War Republican army, was strictly enforced. The few exceptions recorded, such as during emergencies and for the illegitimate sons of legionaries, do not warrant the suggestion that that the rule was routinely ignored.[146]

In the 1st century, the vast majority of auxiliary common soldiers were recruited from the Roman peregrini (second-class citizens). In the Julio-Claudian era, conscription of peregrini seems to have been practiced alongside voluntary recruitment, probably in the form of a fixed proportion of men reaching military age in each tribe being drafted.[147] From the Flavian era onwards, the auxilia were an all-volunteer force.[148] Although recruits as young as 14 are recorded, the majority of recruits (66%) were from the 18–23 age group.[149]

When it was first raised, an auxiliary regiment would have been recruited from the native tribe or people whose name it bore. In the early Julio-Claudian period, it seems that efforts were made to preserve the ethnic integrity of units, even when the regiment was posted in a faraway province. But in the later part of the period, recruitment in the region where the regiment was posted increased and became predominant from the Flavian era onwards.[147] The regiment would thus lose its original ethnic identity.[25] The unit's name would thus become a mere curiosity devoid of meaning, although some of its members might inherit foreign names from their veteran ancestors. This view has to be qualified, however, as evidence from military diplomas and other inscriptions shows that some units continued to recruit in their original home areas e.g. Batavi units stationed in Britain, where some units had an international membership.[73 ] It also appears that the Danubian provinces (Raetia, Pannonia, Moesia, Dacia) remained key recruiting grounds for units stationed all over the empire.[150][151]

It appears that Roman citizens were also regularly recruited to the auxilia. Most likely, the majority of citizen recruits to auxiliary regiments were the sons of auxiliary veterans who were enfranchised on their fathers' discharge.[152] Many such may have preferred to join their fathers' old regiments, which were a kind of extended family to them, rather than join a much larger, unfamiliar legion. There are also instances of legionaries transferring to the auxilia (to a higher rank).[153] The incidence of citizens in the auxilia would thus have grown steadily over time until, after the grant of citizenship to all peregrini in 212, auxiliary regiments became predominantly, if not exclusively, citizen units.

Less clearcut is the question of whether the regular auxilia recruited barbari (barbarians, as the Romans called people living outside the empire's borders). Although there is little evidence of it before the 3rd century, the consensus is that auxilia recruited barbarians throughout their history.[96][154] In the 3rd century, a few auxilia units of clearly barbarian origin start to appear in the record e.g. Ala I Sarmatarum, cuneus Frisiorum and numerus Hnaufridi in Britain.[140][155]

There existed a hierarchy of pay between types of auxiliary, with cavalry higher paid than infantry. One recent estimate is that in the time of Augustus, the annual pay structure was: eques alaris (gregalis) 263 denarii, eques cohortalis 225, and cohors infantryman 188.[156] The same differentials (of about 20% between grades) seem to have existed at the time of Domitian (r. 81-96).[121] However, Goldsworthy points out that the common assumption that rates of pay were universal across provinces and units is unproven. Pay may have varied according to the origin of the unit.[157]

The remuneration of an auxiliary pedes cohortalis may be compared to a legionary's as follows:

legionary ca. 70
amount (denarii)
legionary ca. 70:
annualised (over 25 yrs)
XXX auxiliary ca. 70
amount (denarii)
auxiliary ca. 70
annualised (over 25 yrs)
Stipendium (salary) 225 p.a. 225 188 p.a. 188
Donativa (bonuses) 75 every three yrs 25 none proven
Total annualised pay 250 188
Less: Food deduction 60 60
Less: Equipment etc deductions ca. 50 ca. 50
Net disposable pay 115 78
Praemia (discharge bonus) 3,000 once 120 none proven

Gross salary was subject to deductions for food, clothing, boots and hay (probably for the company mules). It is unclear whether the cost of armour and weapons was also deducted, or borne by the army. Deductions left the soldier with a net salary of 78 denarii. This sum was sufficient, on the basis of the food deduction, to amply feed an adult for a year. In 84 AD Domitian increased basic legionary pay by 33% (from 225 to 300 denarii): a similar increase was presumably accorded to auxiliaries, boosting their net income to 140 denarii, i.e. more than two food allowances.[159] It was entirely disposable, as the soldier was exempt from the poll tax (capitatio), did not pay rent (he was housed in fort barracks) and his food, clothing and equipment were already deducted. It should be borne in mind that most recruits came from peasant families living at subsistence level. To such persons, any disposable income would appear attractive.[160] It could be spent on leisure activities, sent to relatives or simply saved for retirement.

There is no evidence that auxiliaries received the substantial cash bonuses (donativa) handed to legionaries on the accession of a new emperor and other occasions.[161] Although irregular, these payments (each worth 75 denarii to a common legionary) averaged once every 7.5 years in the early 1st century and every three years later. Duncan-Jones has suggested that donativa may have been paid to auxiliaries also from the time of Hadrian onwards, on the grounds that the total amount of donative to the military increased sharply at that time.[162] A very valuable benefit paid to legionaries was the discharge bonus (praemia) paid on completion of the full 25 years' service. At 3,000 denarii, this was equivalent to ten years' gross salary for a common legionary after the pay increase of 84 AD. It would enable him to purchase a substantial plot of land. Again, there is no indication that auxiliaries were paid a discharge bonus. For auxiliaries, the discharge bonus was the grant of Roman citizenship, which carried important tax exemptions. However, Duncan-Jones argues that the fact that service in the auxilia was competitive with the legions (deduced from the many Roman citizens that joined the auxilia) that a discharge bonus may have been paid.[163]

Junior officers (principales)

Below centurion/decurion rank, junior officers in the Roman army were known as principales. An auxiliary cohort's ranks appear the same as in a legionary centuria. These were, in ascending order: tesserarius ("officer of the watch"), signifer (standard-bearer for the centuria), optio (centurion's deputy) and vexillarius (standard-bearer for the whole regiment, from vexillum). In the turmae of cohortes equitatae (and of alae?), the decurion's second-in-command was probably known as a curator, responsible for horses and caparison.[164] As in the legions, the principales, together with some regimental specialists, were classified in two pay-scales: sesquiplicarii ("one-and-a-half-pay men") and duplicarii ("double-pay men").[156] These ranks are probably most closely resembled by the modern ranks of corporal and sergeant respectively.

Besides combat effectives, regiments also contained specialists, the most senior of whom were sesquiplicarii or duplicarii, the rest common soldiers with the status of milities immunes ("exempt soldiers" i.e. exempt from normal duties). Ranking specialists included the medicus (regimental doctor), veterinarius (veterinary doctor, in charge of the care of horses, pack animals and livestock), custos armorum (keeper of the armoury), and the cornicularius (clerk in charge of all the regiment's records and paperwork).[165]

Senior officers

Tombstone of Titus Calidius Severus, of the Camilia Roman tribe, an auxiliary trooper who worked his way up from eques (common cavalryman) to decurion of the cohors I Alpinorum (a mixed infantry/cavalry regiment from the western Alps). He then switched to a legion (presumably after gaining Roman citizenship after 25 of his 34 years of service) and became a decurion in the cavalry arm of Legio XV Apollinaris. He died at age 58, probably shortly after his discharge. Note the portrayal of his chain-mail armour, decurion's crested helmet and horse, led by his equerry, probably a slave. This soldier's long career shows that many auxiliaries served longer than the minimum 25 years, and sometimes joined legions. Erected by his brother, Quintus Calidius. Dates from ante 117, when XV Apollinaris was transferred from Carnuntum (Austria) to the East

The limited evidence on auxiliary centuriones and decuriones is that such officers could be directly commissioned as well as promoted from the ranks. Many appear to have come from provincial aristocracies.[166] Those rising from the ranks could be promotions from the legions as well as from the regiment's own ranks. In the Julio-Claudian period auxiliary centuriones and decuriones were a roughly equal split between citizens and peregrini, though later citizens became predominant due to the spread of citizenship among military families.[167] Because centuriones and decuriones could rise from the ranks, they have often been compared to non-commissioned officers such as sergeants in modern armies. But this comparison certainly undervalues their role and social status. In addition to their military duties, centurions performed a wide range of administrative tasks, which was necessary in the absence of an adequate bureaucracy to support provincial governors. They were also relatively wealthy, due to their high salaries (see table above).[168] A mid-level modern officer such as a major is probably a closer parallel. However, most of the surviving evidence concerns legionary centurions and it is uncertain whether their auxiliary counterparts shared their high status and non-military role.[166]

There is little evidence about the pay-scales of auxiliary centuriones and decuriones, but these are also believed to have amounted to several times that of a miles.[168]

Unlike a legatus legionis (who had an officer staff of 6 tribuni militum and one praefectus castrorum), an auxiliary praefectus does not appear to have enjoyed the support of purely staff officers. The possible exception is an attested beneficiarius ("deputy"), who may have been the praefectus' second-in-command, if this title was a regular rank and not simply an ad hoc appointment for a specific task. Also attached to the praefectus were the regiment's vexillarius (standard-bearer for the whole unit) and cornucen (horn-blower).[164]


It appears that in the 2nd century, the majority of auxiliary prefects were still of Italian origin.[169] In contrast, the evidence for the 3rd century is that Italians provided less than a third of prefects.[170] All prefects were members of the equestrian order, either by birth, or by attaining the property qualification (100,000 denarii, the equivalent of 400 years' gross salary for an auxiliary alaris) or by military promotion. The latter were the chief centurions of legions (centurio primus pilus) who would normally be elevated to equestrian rank by the emperor after completing their single-year term as primuspilus.[171 ]

Equestrians by birth would normally begin their military careers at ca. 30 years of age. Commands were held in a set sequence, each held for 3–4 years: prefect of an auxiliary cohors, tribunus militum in a legion and finally prefect of an auxiliary ala. In Hadrian's time, a fourth command was added, for exceptionally able officers, of prefect of an ala milliaria. Like officers senatorial rank, hereditary equestrians held civilian posts before and after their decade of military service, whereas non-hereditary officers tended to remain in the army, commanding various units in various provinces. By the 3rd century, most auxiliary prefects had exclusively military careers.[171 ][172]

The pay of a praefectus of an auxiliary regiment in the early 2nd century has been estimated at over 50 times that of a miles (common soldier).[112] (This compares to a full colonel in the British Army, who is currently paid about five times a private's salary).[173] The reason for the huge gap between the top and the bottom of the pyramid is that Roman society was far more hierarchical than a modern one. A praefectus was not just a senior officer. He was also a Roman citizen (which most of his men were not) and, as a member of the equestrian order, an aristocrat. The social gulf between the praefectus and a peregrinus soldier was thus immense, and the pay differential reflected that fact.

Names, titles and decorations

Regimental names

The nomenclature of the great majority of regiments followed a standard configuration: unit type, followed by serial number, followed by name of the peregrini tribe (or nation) from whom the regiment was originally raised, in the genitive plural case e.g. cohors III Batavorum ("3rd Cohort of Batavi"); cohors I Brittonum ("1st Cohort of Britons"). Some regiments combine the names of two peregrini tribes, most likely after the merger of two previously separate regiments e.g. ala I Pannoniorum et Gallorum ("1st Wing of Pannonii and Gauls"). A minority of regiments are named after an individual, mostly after the first prefect of the regiment e.g. ala Sulpicia (presumably named after a prefect whose middle (gens) name was Sulpicius). The latter is also an example of regiments that did not have a serial number.[174]


Regiments were often rewarded for meritorious service by the grant of an honorific title. The most sought-after was the prestigious c.R. (civium Romanorum = "of Roman citizens") title. In the latter case, all the regiment's members at the time, but not their successors, would be granted Roman citizenship. But the regiment would retain the c.R. title in perpetuity. Another common title was the gens name of the emperor making the award (or founding the regiment) e.g. Ulpia: the gens name of Trajan (Marcus Ulpius Traianus r.98–117). Other titles were similar to those given to the legions e.g. pia fidelis (p.f. = "dutiful and loyal").[175]


The Roman army awarded a variety of individual decorations (dona) for valour to its legionaries. Hasta pura was a miniature spear; phalerae were large medal-like bronze or silver discs worn on the cuirass; armillae were bracelets worn on the wrist; and torques were worn round the neck, or on the cuirass. The highest awards were the coronae ("crowns"), of which the most prestigious was the corona civica, a crown made oak-leaves awarded for saving the life of a Roman citizen in battle. The most valuable award was the corona muralis, a crown made of gold awarded to the first man to scale an enemy rampart. This was awarded rarely, as such a man hardly ever survived.[161]

There is no evidence that auxiliary common soldiers received individual decorations, although auxiliary officers did. Instead, the whole regiment was honoured by a title reflecting the type of award e.g. torquata (awarded a torque) or armillata (awarded bracelets). Some regiments would, in the course of time, accumulate a long list of titles and decorations e.g. cohors I Brittonum Ulpia torquata pia fidelis c.R.[175].

Everyday life

Tombstone of the auxiliary foot soldier Caius Iulius Baccus, a Roman citizen from Lugdunum (Lyon, France). He probably died while in still a soldier at age 38 after 15 years' service. In view of his incomplete service, he may have been a citizen from birth. His regiment was the Cohors II Thracum and he was still a miles (common soldier) when he died. Unlike many military tombstones, this one portrays the deceased in a non-military pose, enjoying wine at his home (which is presumably how his friends, who arranged the memorial, wished to remember him). Römisch-Germanisches Museum, Cologne, Germany

The professional soldiers of the Principate, both legionary and auxiliary, were in combat operations for only a tiny fraction of their working careers. Most of their days were spent on routine duties, both military and non-military. These, together with soldiers' social and private lives, are virtually ignored by contemporary historians such as Tacitus and Dio Cassius. The surviving documentary evidence of soldiers' lives is minimal. This is due to organic decomposition, not to a lack of written documentation in the Roman army. On the contrary, the army was highly bureaucratised. Even minor matters such as soldiers' requests to their praefectus for leave (commeatus) had to be submitted in writing.[176] Detailed records were kept on all individual soldiers and there is evidence of filing systems.[177] From what has been discovered at Vindolanda, it can be deduced that the garrison in Britain alone generated tens of millions of documents.[178]

Until the breakthrough discovery in the 1970s of the Vindolanda Tablets, most of the evidence for everyday life of auxiliaries was found in papyri, recovered mostly in Egypt. It is thin compared to the legionary evidence and relates mostly to units in Egypt and the East. In contrast, the Vindolanda Tablets emanate from the northwestern provinces of the empire. They consist of a series of letters and memoranda, engraved on wooden tablets, between officers of three auxiliary regiments from Germania Inferior that succeeded each other in the fort of Vindolanda in northern England. They date from the period 85–122, preceding the construction of Hadrian's Wall.[179]

The most informative documents are renuntiae, unit strength and deployment reports which were drawn up periodically for the regiment's praefectus; and pridiana, or duty rosters, (from pridie "the previous day"), which were prepared daily for the following day and presumably posted on notice-boards in the fort for all to see. These collectively show that auxiliary soldiers were engaged in a wide variety of activities, on-base and off-base, military and non-military in nature.[180]

Military duties

The routine military duties of auxiliaries included patrolling, guard-duty, and weapons training. These were not limited to the regiment's base fort and its vicinity only: the Vindolanda tablets show that detachments of the unit could be deployed in several different locations at once: one renuntia shows a detachment of nearly half the effectives of cohors I Tungrorum deployed at another fort.[181] A papyrus renuntia for cohors I Hispanorum veterana equitata in Moesia Inferior (105 AD) reports a cavalry turma on a scouting mission (exploratum) across the Danube.[182] Combat-training and exercises were a central part of an auxiliary's weekly routine. One tablet probably contains a scathing comment from an officer about the horsemanship of young provincial trainees in the cohors equitata: "on horseback, too many of the pathetic little Brits (Brittunculi) cannot swing their swords or throw their javelins without losing their balance".[183] Parades were another important part of a regiment's routine. As in today's armies, each day would begin with a roll-call parade (probably called a numeratio[184]). Occasional parades included religious rites and purely military parades such as the rosaliae signorum (decoration of the standards) and demissio, when veterans were discharged after completing their term of service and awarded their diplomas of Roman citizenship.[185] There would also be military exercises, in which soldiers displayed their combat skills, when the regiment was inspected by a high official: the legatus legionis (legion commander), legatus Augusti (provincial governor) or even the emperor himself.[182]

Fort duties

Non-military duties on-site included the routine chores of fort life (cleaning, washing clothes and equipment, feeding horses) and working in the fort's fabrica (workshop where armour and weapons were made and repaired)[181]. An essential activity was the procurement of the supplies the regiment needed. For raw materials, the army purchased what it could locally, and imported the rest from elsewhere. The men of I Hispanorum veterana went as far afield (from Moesia Inferior) as Gaul to procure clothing and grain.[186] For manufactured goods, the regiments would produce some of their needs themselves e.g. evidence of leather-tanning and beer-brewing at Vindolanda and nearby Catterick fort.[187] The tablets attest the procurement of cereals, beer, animal fodder; manufactured goods such as clothing, nails and vehicle parts; raw materials such as stone, iron, lead, timber, animal hides.[188] Some soldiers with specialist skills were given the status of immunes, meaning they were exempt from normal duties and chores so that they could practice their trade. Attested specialists include scutarii ("shield-men"), probably blacksmiths and other craftsmen who worked in the fabrica; carpentarii ("wagon-drivers", or alternatively, "carpenters"); seplasiarii ("ointment-men"), medical orderlies who worked in the hospitium (fort hospital); balniator (bath attendant); and cervesarius (beer brewer).[189] It is uncertain, however, whether these jobs were all held by milities immunes or some by civilians working for the unit on contract.[190]

View of the remains of Hadrian's Wall (built 122–32 AD) with (foreground) the foundations of Milecastle 39. Unlike for the 3 legions involved in this massive project, no record has been found of auxiliary construction activity on the Wall. But since auxilia outnumbered legionaries by 2 to 1 in Britain at the time, it is considered certain they were heavily engaged, maybe to dig the large parallel ditch. In the 2nd century, some 35,000 auxiliaries were deployed on or around Hadrian's Wall: ca. 15% of the entire auxilia corps
Bas-relief of Thracian hero. The relief is incomplete, missing the rider's lance and victim. Histria Museum, Romania
Wall painting showing Mithras slaying a bull, the central ritual act of the Mithraic cult (the tauroctony). Note Mithras' Phrygian cap, his cloak containing the celestial firmament, the serpent and the cave in which the cult act is taking place. Mithraic temples sought to reproduce a cave-like environment. The symbolism, rites and tenets of the cult are obscure.[191 ] From Dura Europos, on the Euphrates, Syria


A major non-military activity of the Roman army was construction. The army was a large workforce of fit, disciplined men skilled in building techniques and other crafts. They were on regular salaries anyway, so it was cheaper for the government to use troops for big projects, if the security situation in the province allowed, than to hire private contractors. Soldiers naturally built forts and fortifications e.g. Hadrian's Wall itself was built by the army. But they also built much of a province's infrastructure: trunk Roman roads, bridges, docks, canals, aqueducts, entire new cities such as coloniae for veteran legionaries, public buildings (e.g. basilicas and amphitheatres).[192] The army also carried out large-scale projects to increase the land available for agriculture, such as forest clearance, draining marshes (e.g. the large-scale drainage of the Fens in eastern England, which were probably developed as a huge imperial estate)[193]. Most of the available evidence relates to legionary construction. But the Vindolanda tablets attest auxiliaries' construction activity e.g. one tablet refers to 12 soldiers detailed to work on the construction of a bath-house (balneum) at Vindolanda. Another possibly refers to the construction of a bridge elsewhere.[194] The Roman army also operated many of the mines and quarries that produced the raw materials it needed for weapons and armour manufacture and for construction. Soldiers would supervise the slave-gangs that generally worked the mines, or mine themselves at times of urgent demand.[195]

Police duties

Off-site duties included many routine police and even administrative tasks. Provincial governors had only a minimal administrative staff at their disposal, and no regular police force.[196] They therefore relied on their troops for many such duties e.g. escorting the governor or other senior officials, patrolling highways, assisting and escorting tax collectors and military supply-wagons, carrying official despatches, arresting wanted men.[197] Thus a renuntia shows a detachment of 46 men of I Tungrorum on escort duty (singulares) with the provincial governor's staff.[181]

Highways were routinely garrisoned and patrolled along their entire length. Small detachments of troops would be on duty at the way-stations: mutationes (relay stations where horses could be changed) and mansiones (large wayside inns, with accommodation, stables, taverna and baths).[198] These stations may well be the six unidentified locations where small detachments of ca. 10 men, each under a centurion, were deployed according to a renuntia of cohors I Tungrorum.[199] They would check the identities and cargoes of road users as well as escorting the vehicles of the cursus publicus (imperial transport service). This service was concerned with the transportation of official personnel and payloads: senior officials, tax revenues and wages for the troops, military supplies (usually conveyed in convoys of ox-drawn wagons) and official post. Such vehicles, especially the money-cars, were vulnerable to highway robbers e.g. one eques (cavalryman) of I Hispanorum veterana was reported killed by robbers in a renuntia.[186] Auxiliary troops would also assist agents of the procurator (the senior financial official in the province) to collect the portorium, an imperial toll on the carriage of goods on public roads, payable whenever the goods crossed a toll-line.[200] Despatch-riders (dispositi), normally equites cohortales, would also be stationed at mutationes to form relays to carry messages rapidly between forts.[182] Relays of fresh riders and horses, careering at full gallop, could maintain an average speed of 32 km/h (20 mph): thus an urgent despatch from the legionary base at Eboracum (York) to the provincial governor's headquarters in London (300 km; 200 miles), a journey of about ten days for a single rider and mount, could be delivered in just ten hours.[201]

Social life

All the Vindolanda documents are written by officers, supporting the view that many of the lower ranks may have been illiterate.[166] The language used is always Latin, usually of a reasonable standard. Most of the authors were Gauls, Britons or Germans, whose native languages were Celtic or Germanic, yet they wrote even to their relatives in Latin.[202] This does not mean that they could no longer speak their native tongues, simply that those tongues never developed a written form. The tablets show that superior officers were addressed as domine ("master") and soldiers of the same rank as frater ("brother") or collega ("comrade").[203] The letters show that an auxiliary soldier maintained friendships not just in his own regiment, but also in other regiments and even in the legions. Hunting was a favourite leisure activity, for the officers at least.[204]


Roman religion was polytheistic and therefore readily accepted and absorbed many deities of the empire's subjects, the vast majority of whose cultures were also polytheistic. But there were limits: the Romans forbade cults whose beliefs or practices were considered incompatible with the basic tenets of Roman religion. For example, the Romans proscribed cults that practiced human sacrifice, which was partly the reason why Druidism was banned under Emperor Tiberius.[205] b[›] Also banned was Christianity, de facto initially, as membership of the Christian church was not prohibited formally until the rule of Septimius Severus (197-211)[206]. As it was monotheistic, its followers refused to participate in the imperial cult, the worship of the imagines (cult portraits or statues) of ruling and past emperors. The cult was used by the Romans in the same way as an oath of allegiance is used by modern societies - as an affirmation of loyalty to the state. It was compulsory for all peregrini to make burnt sacrifice to the image of the ruling emperor at least once (certificates were issued to prove compliance). Refusal was considered treasonous and was punishable by death.[207] Christians were also widely suspected, through a misunderstanding of baptism and the eucharist, of practicing clandestine ritual murder of infants (by drowning) and cannibalism respectively, violating two more Roman taboos.[205]

In theory, soldiers were only permitted to honour such non-Roman gods as had been officially approved by the collegium pontificum ("Board of High Priests") in Rome, which regulated the state religion. The board would assess whether a foreign cult was acceptable. If so, by the process of interpretatio Romana, a non-Roman god was officially annexed to a Roman god on the basis of shared characteristics[208] e.g. Mars Toutates, the assimilation of a Gallic deity to the Roman god of war.[209] But in practice, off-duty soldiers were allowed to follow whatever cults they pleased, providing they were not specifically prohibited. Many surviving military dedications, especially those offered by the lower ranks, are to non-Roman deities alone.[210]

Auxiliary soldiers were, however, required to participate in a number of official Roman religious rites held by their regiment at regular times in the year. These included religious parades in honour of the most important Roman gods, especially Jupiter, the supreme god of the Roman pantheon: many altars and tombstones dedicated by the military are headed with the letters IOM (Iovi Optimo Maximo: "to Jupiter the Best and Greatest"); Mars, the god of war; and Minerva, a goddess also associated with war. These parades were probably accompanied by animal sacrifices and feasting. Another important regimental cult was emperor-worship. Parades were held on imperial birthdays, when the imagines of the ruling emperor, and of deified previous emperors, would be saluted and offered sacrifices by the prefect of the regiment.[211]

Outside of the regimental ceremonies, auxiliary soldiers revered a vast array of deities.[212] These can be divided into three categories: Roman gods; their own native gods ,such as the Thracian hero which is often represented on the tombstones of Thracian veterans as a mounted warrior spearing a beast (or man) on the ground; and the local gods of the province in which they served, such as the cult of Coventina in Britain. Coventina was a British nymph associated with springs. Several dedications to her have been found e.g. offered by the garrison of the auxiliary fort at Carrawburgh (on Hadrian's Wall).[213]

From the 2nd century onwards, Eastern mystery cults, centred on a single deity (though not necessarily monotheistic) and based on sacred truths revealed only to the initiated, spread widely in the empire, as polytheism underwent a gradual, and ultimately terminal, decline. One such cult, that of Sol Invictus ("The Invincible Sun"), was designated as the official army-cult by the emperor Aurelian (r. 270-5) and remained such until the time of Constantine. But by far the most popular among the Roman military was Mithraism, centred on a deity called Mithras. The mainstream view is that this originated in the Persian cult of Mithra, but the salient features of the Roman cult are absent in the Avesta and other Iranian evidence. It is thus possible that the Roman cult was not connected to the Iranian (except perhaps that the deity's name was borrowed) and instead was native to the eastern provinces of the empire itself e.g. Anatolia.[214] Most likely, Mithraism was a medley of elements from various cults - hence its apparent adoption of a Persian deity-name, of the taurobolium ritual from the cult of Cybele, and of the Phrygian cap. Based on secret initiation ceremonies and rites, this cult is attested, for example, by the discovery of a Mithraeum (Mithraic temple) at Carrawburgh fort near Hadrian's Wall. It is likely that its membership was restricted due to limited space for religious ceremonies. Membership, according to the written evidence of dedications in Nida (Heddernheim), was not restricted according to social standing.[191 ][215] Another eastern mystery cult, Christianity, was much less common amongst the military until it was accorded favoured-cult status by Constantine the Great in the early 4th century. This was because it was based on a pacifist ideology and also because it was a proscribed cult which was subject to periodic persecution. Nevertheless, it probably had some clandestine followers in the military during the 2nd and 3rd centuries, especially in the East, where it had spread widely.[216] The discovery of a Christian house church with the earliest Christian paintings extant (early 3rd century) at the fortress town of Dura-Europos in Syria may indicate a Christian element in that town's garrison.[217]

Deployment in the 2nd century

ROMAN AUXILIARY REGIMENTS: Summary of known deployments c. 130 AD[218]
Province Approx. modern
(no. milliariae)
(no. mill.)
XXX Cavalry
Britannia England/Wales 11 (1) 45 (6) 56 10,688 25,520 36,208 3 16,500 52,708
Rhine Frontier
Germania Inferior S Neth/NW Rhineland 6 17 23 4,512 8,160 12,672 2 11,000 23,672
Germania Superior Pfalz/Alsace 3 22 (1) 25 3,336 10,880 14,216 2 11,000 25,216
Danube Frontier
Raetia/Noricum S Ger/Switz/Austria 7 (1) 20 (5) 27 5,280 11,220 16,500 1 5,500 22,000
Pannonia (Inf + Sup) W Hungary/Slovenia 11 (2) 21 (4) 32 8,304 11,360 19,664 3 16,500 36,164
Moesia Superior Serbia 2 10 12 1,864 4,800 6,664 2 11,000 17,664
Moesia Inferior N Bulgaria/coastal Rom 5 12 17 3,520 5,760 9,280 1 5,500 14,780
Dacia (Inf/Sup/Poroliss) Romania 11 (1) 32 (8) 43 7,328 17,920 25,248 2 11,000 36,248
Eastern Frontier
Cappadocia Central/East Turkey 4 15 (2) 19 3,368 7,840 11,208 3 16,500 27,708
Syria (inc Judaea/Arabia) Syria/Leb/Palest/Jordan/Israel 12 (1) 43 (3) 55 10,240 21,600 31,840 5 27,500 59,340
North Africa
Aegyptus Egypt 4 11 15 3,008 5,280 8,288 2 11,000 19,288
Mauretania (inc Africa) Tunisia/Algeria/Morocco 10 (1) 30 (1) 40 7,796 14,720 22,516 1 5,500 28,016
Internal provinces 2 15 17 2,224 7,200 9,424 1 5,500 14,924
TOTAL EMPIRE 88 (7) 293 (30) 381 71,468 152,260 223,728 28 154,000 377,728


Roman Empire during Hadrian's reign
  1. The table shows the importance of auxiliary troops in the 2nd century, when they outnumbered legionaries by 1.5 to 1.
  2. The table shows that legions did not have a standard complement of auxiliary regiments[219] and that there was no fixed ratio of auxiliary regiments to legions in each province. The ratio varied from six regiments per legion in Cappadocia to 40 per legion in Mauretania.
  3. Overall, cavalry represented about 20% (including the small contingents of legionary cavalry) of the total army effectives. But there were variations: in Mauretania the cavalry proportion was 28%.
  4. The figures show the massive deployments in Britannia and Dacia. Together, these two provinces account for 27% of the total auxilia corps.


^ a:  Lorica segmentata: Much has been made of the clear difference in armour between the two corps shown on Trajan's Column. This is a monument erected in 113 in Rome to commemorate the conquest of Dacia by Emperor Trajan (r. 97–117): its bas-reliefs are a key source for Roman military equipment. Auxilia are generally shown wearing chain mail (lorica hamata) cuirasses or simple leather corslets, and carrying oval shields. Legionaries are depicted wearing laminated-strip armour (lorica segmentata) at all times (whether in combat or in other activities, such as construction) and with curved rectangular shields.[137] But the figures in Trajan's Column are highly stereotyped, in order to distinguish clearly between different types of troops.[220] On another Trajanic monument, the Adamclisi Tropaeum, the lorica segmentata does not appear at all, and legionaries and auxilia alike are depicted wearing either chain mail or scales (lorica squamata). There is general recognition that the Adamclisi monument is a more accurate portrayal of normality, with the segmentata used rarely, maybe only for combat and parades.[221] Testing of replica segmentata by reenactors has shown that it is uncomfortable and that chafing makes it painful to wear for more than short periods. On the plus side, it provides more effective protection than the other armour types: it is impenetrable to most arrow or spear strikes.[222] It has been argued that the lorica segmentata was used by auxiliaries also. But there is no firm evidence for this. Traces of this type of armour have been found in forts in Raetia from a time when no legions were stationed in the province.[223] But these may simply have been left behind by legionaries on temporary detachment. Furthermore auxilia are nowhere depicted wearing such armour.[114] The provision of more protective and expensive armour to legionaries was probably due to non-military reasons: the army was highlighting their social superiority, just as it did with higher pay. During the 3rd century, when all peregrini were granted citizenship, and therefore legionaries lost their social superiority, the lorica segmentata and the rectangular shield disappeared.[224]

^ b:  Roman human sacrifice: The Romans themselves only definitively banned human sacrifice, by senatorial decree, in 97 BC.[225] But it was by then very rare, only practiced in times of extreme national emergency. e.g. after their disastrous defeat at the Battle of Cannae (216 BC), the Romans had, after consulting the Sibylline Books, buried alive in the Forum Boarium (Cattle Market), a pair of Gauls and a pair of Greeks.[226]


  1. ^ Goldsworthy (2000) 44
  2. ^ Goldsworthy (2000) 51
  3. ^ Goldsworthy (2000) 49
  4. ^ a b c Holder (2003) 145
  5. ^ a b Hassall (2000) 320
  6. ^ Goldsworthy (2000) 74–5
  7. ^ Goldsworthy (2000) 78–9
  8. ^ a b c Goldsworthy (2000) 126
  9. ^ Goldsworthy (2000) 107
  10. ^ Keppie (1996) 372
  11. ^ Keppie (196) 375
  12. ^ Livy Ab Urbe Condita XXII.37
  13. ^ G.L. Cheesman, The Auxilia of the Roman Imperial Army (Oxford, 1914), 8–9.
  14. ^ Keppie (1996) 373
  15. ^ Keppie (1996) 379
  16. ^ a b c d e f g h Goldsworthy (2000) 127
  17. ^ Holder (1980) 7
  18. ^ Goldsworthy (2000) 214
  19. ^ Goldsworthy (2003) 27
  20. ^ Holder (1980) 9
  21. ^ Keppie (1996) 382
  22. ^ Holder (1982) 110-3
  23. ^ Tacitus Annales IV.5
  24. ^ Goldsworthy (2003) 51
  25. ^ a b c d Keppie (1996) 396
  26. ^ Goldsworthy (2000) 119
  27. ^ Holder (1982) 145
  28. ^ Dio LV.29.1
  29. ^ Dio LV.29.2
  30. ^ Dio LV.29.3
  31. ^ Dio LV.29.4
  32. ^ Dio LV.30.1
  33. ^ Dio LV.31.1
  34. ^ a b Suetonius III.16
  35. ^ Goldsworthy (2003) 64
  36. ^ Dio LV.30.6
  37. ^ Dio LV.30.5
  38. ^ Suetonius III.17
  39. ^ Goldsworthy (2000) 165-6
  40. ^ a b c d e Keppie (1996) 391
  41. ^ Military Diplomas Online Introduction
  42. ^ Keppie (1996) 390
  43. ^ a b Tacitus Historiae IV.18
  44. ^ Tacitus Historiae IV.12
  45. ^ Birley (2002) 43
  46. ^ Scheidel (2006) 9
  47. ^ Tacitus Germania 29.1 and Historiae II.28
  48. ^ Dio Cassius LXIX.9.6
  49. ^ Tacitus Historiae IV.12
  50. ^ Tacitus Annales IV.12
  51. ^ Tacitus Historiae IV.13
  52. ^ Tacitus Historiae II.5
  53. ^ Tacitus Historiae I.64, II.66
  54. ^ Tacitus Historiae IV.14
  55. ^ Tacitus Historiae IV.13
  56. ^ Tacitus Historiae IV.54
  57. ^ Tacitus Historiae IV.24, 27
  58. ^ Tacitus Historiae IV.15-6
  59. ^ Tacitus Historiae IV.16
  60. ^ Tacitus Historiae IV.20
  61. ^ Tacitus Historiae IV.21, 28
  62. ^ Tacitus Historiae IV.33, 66, 67
  63. ^ Tacitus Historiae
  64. ^ Tacitus Historiae IV.68
  65. ^ Tacitus Historiae V
  66. ^ Tacitus Historiae V.26
  67. ^ Birley (2002) 44
  68. ^ Tacitus Agricola 35-8
  69. ^ Notitia Dignitatum Titles IV and V
  70. ^ Mattingly (2006) 132
  71. ^ Roxan (2003); Holder (2006)
  72. ^ Keppie (1996) 394
  73. ^ a b Mattingly (2006) 168–9
  74. ^ Hassall (2000) 332–4
  75. ^ Goldsworthy (2003) 138
  76. ^ Spaul (2000) 526
  77. ^ (Holder (2003) 145
  78. ^ a b Holder (2003) 119
  79. ^ Goldsworthy (2000) 152 (map): Legiones II and III Italica under Marcus Aurelius (r. 161–80) and I, II and III Parthica under Septimius Severus (r. 197–211)
  80. ^ 25 legions of 5,000 men each
  81. ^ 28 legions of 5,500 each (double-strength 1st cohorts introduced under Domitian (r. 81–96)
  82. ^ Goldsworthy (2000) 152 (map): 33 legions of 5,500 each
  83. ^ Tacitus Annales IV.5
  84. ^ Holder (2003) 120
  85. ^ J. C. Spaul ALA (1996) 257–60 and COHORS 2 (2000) 523–7 identify 4 alae and 20–30 cohortes raised in the late 2nd/early 3rd centuries
  86. ^ Goldsworthy (2003) 58: 9 cohorts of 480 men each plus German bodyguards
  87. ^ Goldsworthy (2003) 58: 9 double-cohorts of 800 men each plus 2,000 equites singulares
  88. ^ Implied by Tacitus Annales
  89. ^ Hassall (2000) 320 estimates 380,000
  90. ^ MacMullen How Big was the Roman Army? in KLIO (1979) 454 estimates 438,000
  91. ^ Assuming 33% drop in nos. due to war/disease
  92. ^ John Lydus De Mensibus I.47
  93. ^ Holder (2006) 985; Roxan (2003) 672
  94. ^ Campbell (2005) 212
  95. ^ The Roman Law Library Constitutio Antoniniana de Civitate
  96. ^ a b Goldsworthy (2003) 74
  97. ^ a b Elton (1996) 148–52
  98. ^ Goldsworthy (2000) 162
  99. ^ D. Ch. Stathakopoulos Famine and Pestilence in the late Roman and early Byzantine Empire (2007) 95
  100. ^ Zosimus New History 26, 37, 46
  101. ^ MacMullen (1979) 455
  102. ^ Lee (1997) 223
  103. ^ list of alae
  104. ^ Dio LXXI
  105. ^ Jones (1964) 620
  106. ^ Goldsworthy (2003) 206
  107. ^ Jones (1964) 610
  108. ^ Notitia Dignitatum passim
  109. ^ Goldsworthy (2000) 174
  110. ^ Vegetius III.3
  111. ^ Hassall (2000) 332-4
  112. ^ a b c Birley (2002) 46
  113. ^ Arrian Ars Tactica 17.3
  114. ^ a b Goldsworthy (2003) 136
  115. ^ Goldsworthy (2003) 52-3
  116. ^ Goldsworthy (2000) 52
  117. ^ Goldsworthy (2003) 138–9
  118. ^ Goldsworthy (2003) 168
  119. ^ Cheesman (1914)
  120. ^ Davies (1988) 141-3
  121. ^ a b Hassall (2000) 336
  122. ^ Tacitus Historiae IV
  123. ^ Tacitus Historiae I.59, IV.12
  124. ^ Goldsworthy (2003) 154
  125. ^ Tacitus Annales 12.31-40
  126. ^ Rossi (1971) 118
  127. ^ Goldsworthy (2000) 124 (map) and 152 (map)
  128. ^ Mattingly (2006) 162-3, 188; Goldsworthy (2000) 156
  129. ^ Goldsworthy (2000) 140
  130. ^ Holder (2003) 135, 133
  131. ^ Livy XXXV.12
  132. ^ Rossi (1971) 104
  133. ^ Sidnell (2006) 172
  134. ^ Campbell (2003) 212
  135. ^ Holder (2003) 140
  136. ^ Holder (2003)
  137. ^ a b c Rossi (1971) 102
  138. ^ a b c Goldsworthy (2003) 137
  139. ^ Elton (1996) 105
  140. ^ a b Mattingly (2006) 223
  141. ^ Grant (1985) 72
  142. ^ Rossi (1971) 104.
  143. ^ Dio Cassius LXXI.16
  144. ^ Based on data in Goldsworthy (2003) 95-5; Holder (1980) 86-96; Elton (1996) 123
  145. ^ Davies (1988) 148
  146. ^ Goldsworthy (2003) 78, 80
  147. ^ a b Holder (1980) 123
  148. ^ Goldsworthy (2003) 76
  149. ^ Holder (1980) 138
  150. ^ Military Diplomas Online Introduction
  151. ^ RMD Vol V Appendix 4 e.g. RMD 127, 128
  152. ^ Mattingly (2006) 190
  153. ^ Holder (1980) 86–8
  154. ^ Heather (2005) 119
  155. ^ List of auxiliary units in Britain
  156. ^ a b Goldsworthy (2003) 94
  157. ^ Goldsworthy (2003) 95
  158. ^ Based on figs in Goldsworthy (2003) 94; Duncan-Jones (1994) 33–41
  159. ^ Duncan-Jones (1994) 34
  160. ^ Jones (1964) 647
  161. ^ a b Goldsworthy (2003) 96
  162. ^ Duncan-Jones (1994) 40
  163. ^ Duncan-Jones (1994) 36
  164. ^ a b Birley (2002) 47
  165. ^ Birley (2002) 47–8; Vindolanda Tablets Online Introduction: Personnel
  166. ^ a b c Goldsworthy (2003) 73
  167. ^ Holder (1980) 86-8
  168. ^ a b Goldsworthy (2003) 72
  169. ^ Prosopographia Militiarum Equestrium Vol V (2001)
  170. ^ Holder (1982) 65
  171. ^ a b Goldsworthy (2003) 65–6
  172. ^ Goldsworthy (2000) 165
  173. ^
  174. ^ Holder (1980) Chapter 2
  175. ^ a b Goldsworthy (2003) 97
  176. ^ Vindolanda Tablets 166-177
  177. ^ Goldsworthy (2003) 90
  178. ^ Mattingly (2006) 200
  179. ^ Mattingly (2006) 162
  180. ^ Mattingly (2006) 163
  181. ^ a b c Vindolanda Tablet 154
  182. ^ a b c Davies (1988) 146
  183. ^ Vindolanda Tablet 164 (my translation)
  184. ^ Vindolanda Tablet 242
  185. ^ Goldsworthy (2003) 92
  186. ^ a b Renuntia displayed in Goldsworthy (2003) 145
  187. ^ Vindolanda Tablets 182, 343
  188. ^ Vindolanda Tablets 155, 180, 182, 183, 184, 207, 309
  189. ^ Birley (2002) 48
  190. ^ Vindolanda Tablets Online Introduction: Soldiers and Civilians
  191. ^ a b Goldsworthy (2003) 112-3
  192. ^ Goldsworthy (2003) 146-8
  193. ^ D.J. Thompson in Wacher (1988) 557
  194. ^ Vindolanda Tablets 155, 258
  195. ^ Goldsworthy (2003) 249
  196. ^ Burton (1988) 424-6
  197. ^ Goldsworthy (2003) 149
  198. ^ Goldsworthy (2003) 91
  199. ^ Vindolanda tablet 154
  200. ^ Burton (1988) 428
  201. ^ Using average speeds achieved by the Pony Express in the American West, 19th century
  202. ^ Vindolanda Tablet 346
  203. ^ Vindolanda Tablets 166, 311
  204. ^ Vindolanda Tablets 311, 174, 213
  205. ^ a b Pliny the Elder XXX.4
  206. ^ Catholic Encyclopedia Martyr
  207. ^ Pliny the Younger Letters X.9
  208. ^ Tacitus Germania 43
  209. ^ Mattingly (2006) 484
  210. ^ Mattingly (2006) 214-6
  211. ^ Goldsworthy (2003) 108
  212. ^ Goldsworthy (2003) 110
  213. ^ Mattingly (2006) 215
  214. ^ cf. Plutarch Pompey 24
  215. ^ Meier-Arendt Römische Steindenkmäler aus Frankfurt am Main, Museum für Vor- und Frühgeschichte Frankfurt, Archäologische Reihe 1(1983)
  216. ^ Goldsworthy (2003) 212
  217. ^ S. James Dura-Europos:Pompeii of the Desert 4
  218. ^ Auxiliary unit figures from Holder (2003) 145
  219. ^ Goldsworthy (2000)
  220. ^ Rossi (1971) 59
  221. ^ Mattingly (2006) 207
  222. ^ Goldsworthy (2003) 129
  223. ^ Hassall (2000) 337
  224. ^ Goldsworthy (2003) 209
  225. ^ Pliny the Elder XXX.3
  226. ^ Livy XXII.57

See also




  • Birley, Anthony (2002). Band of Brothers: Garrison Life at Vindolanda.  
  • Burton, G. (1988). The Roman World (J. Wacher ed.).  
  • Campbell, Brian (2005). "The Army" in Cambridge Ancient History 2nd Ed Vol XII (The Crisis of Empire 193-337).  
  • Davies, R.W. (1988). Service in the Roman Army.  
  • Duncan-Jones, Richard (1990). Structure and Scale in the Roman Economy.  
  • Duncan-Jones, Richard (1994). Money and Government in the Roman Empire.  
  • Elton, Hugh (1996). Frontiers of the Roman empire.  
  • Goldsworthy, Adrian (2000). Roman Warfare.  
  • Goldsworthy, Adrian (2003). Complete Roman Army.  
  • Grant, Michael (1985). The Roman Emperors.  
  • Hassall, Mark (2000). "The Army" in Cambridge Ancient History 2nd Ed Vol XI (The High Empire 70-192).  
  • Holder, Paul (1980). Studies in the Auxilia of the Roman Army.  
  • Holder, Paul (1982). The Roman Army in Britain.  
  • Holder, Paul (2003). Auxiliary Deployment in the Reign of Hadrian.  
  • Holder, Paul (2006). Roman Military Diplomas V.  
  • Keppie, Lawrence (1996). "The Army and the Navy" in Cambridge Ancient History 2nd Ed Vol X (The Augustan Empire 30BC - 69 AD).  
  • Luttwak, Edward (1976). Grand Strategy of the Roman Empire.  
  • Mattingly, David (2006). An Imperial Possession: Britain in the Roman Empire.  
  • Jones, A.H.M. (1964). The Later Roman Empire.  
  • Rossi, L. (1971). Trajan's Column and the Dacian Wars.  
  • Roxan, Margaret (2003). Roman Military Diplomas IV.  
  • Spaul, John (2000). COHORS2.  

External links


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