Auxiliaries (Roman military)

Auxiliaries (Roman military)

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, to increase the process of romanisation and unification of the provinces into a single empire. 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

Roman Republic (to 30 BC)

The core of the Roman republic's fighting machine was the manipular legion, which was a heavy infantry unit adapted to close-quarter engagements on more or less any terrain probably adopted sometime during the Samnite Wars (343–290 BC). [Goldsworthy (2000) 44] But 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). [Goldsworthy (2000) 51] 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 small. In addition the legion lacked missile forces such as slingers and archers. [Goldsworthy (2000) 49]

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 three 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, however, remained modest: a normal consular army of two legions and two "alae" contained "ca." 17,500 infantry and 2,400 cavalry ("ca." 12% of the total force). [Goldsworthy (2000) 52] This compares with 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). [Holder (2003) 145] [Hassall (2000) 320]

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 enemies that deployed far more powerful cavalry elements, the Roman deficiency in cavalry resulted in heavy defeats. The dangers were shown during the sporadic major invasions of Italy by the Gauls, and the expedition of the Greek king Pyrrhus of Epirus (275 BC). The decisive turning point was the Second Punic War (218–202 BC). 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. [Goldsworthy (2000) 74–5] 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. [Goldsworthy (2000) 78–9] 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). [Goldsworthy (2000) 126]

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. [Goldsworthy (2000) 107] Furthermore, Roman equestrians were no longer required to perform cavalry service after this time. [Keppie (1996) 372] The late Republican legion was thus wholly bereft of cavalry (a tiny cavalry force of 120 men was added back to the legion under Augustus). [Keppie (1996) 375]

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. [Livy "Ab Urbe Condita" XXII.37] 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. [G.L. Cheesman, "The Auxilia of the Roman Imperial Army" (Oxford, 1914), 8–9.]

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. [Keppie (1996) 373]

Rule of 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. [Keppie (1996) 379] 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 all-volunteer professionals serving in permanent units. [Goldsworthy (2000) 126]

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). [Goldsworthy (2000) 127]

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). [Holder (1980) 7] "Alae" were divided into "turmae" (squadrons) of 30 (or 32) men, each under a "decurio" (literally: "leader of ten"). [Goldsworthy (2000) 214] 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"). [Goldsworthy (2003) 27] "Cohortes equitatae" were simply infantry "cohortes" with a cavalry contingent of four "turmae" added. [Holder (1980) 9]

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. [Keppie (1996) 382]

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). [Holder (1982) 110-3]

Recruitment was thus heavy throughout the Augustan period, with a steady increase in the number of units formed. By 23 AD, there were roughly the same numbers of auxiliaries in service as there were legionaries. [Tacitus "Annales" IV.5] 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. [Goldsworthy (2003) 51]

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. [Keppie (1996) 396]

Arminius (Hermann in modern German) 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). [Goldsworthy (2000) 119]

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. [Holder (1982) 145] But discontent was festering among the Illyrian tribes due to what they saw as the rapacity of Roman tax officials. [Dio LV.29.1] 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. [Dio LV.29.2] 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. [Dio LV.29.3] 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. [Dio LV.29.4]

Augustus ordered Tiberius to break off operations in Germany and move his main army to Illyricum. [Dio LV.30.1] 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. [Dio LV.31.1] The Romans had now deployed no less than 15 legions and an equivalent number of auxilia. [Suetonius III.16] Ths amounts to a total of "ca." 150,000 men. It included 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). [Goldsworthy (2003) 64] [Goldsworthy (2000) 127] In addition, the regular forces were assisted by a large number of allied troops from neighbouring Thracia deployed by their king Rhoemetalces, a Roman "amicus" (puppet king). [Dio LV.30.6]

The Romans faced further reverses on the battlefield and a savage guerrilla war in the Bosnian mountains. [Dio LV.30.5] 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. [Suetonius III.16] Tiberius finally quelled 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. [Suetonius III.17]

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. [Goldsworthy (2000) 165-6]

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. [Keppie (1996) 391] 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. [ "Military Diplomas Online Introduction"] Claudius also decreed that prefects of auxiliary regiments must all be of equestrian rank, thus excluding centurions from such commands. [Keppie (1996) 391] 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. [Keppie (1996) 391]

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. [Keppie (1996) 390]

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%). [Holder (2003) 145] By the rule of Nero (54–68), auxiliary numbers may have reached, by one estimate, about 200,000 men, implying about 400 regiments. [Keppie (1996) 391]

Revolt of the Batavi (69–70 AD)

The second major episode of auxiliary mutiny came over half a century after the Illyrian revolt. The Batavi were a sub-tribe of the Germanic Chatti tribal group who had migrated to the region between the Old Rhine and Waal rivers (still today called the Betuwe after them) in what became the Roman province of Germania Inferior (S Netherlands). Their land, though potentially fertile alluvial deposits, was largely uncultivable, consisting mainly of Rhine delta swamps. Thus the Batavi population it could support was tiny: not more than 35,000 at this time. [Birley (2002) 43]

They were a warlike people, skilled horsemen, boatmen and swimmers. They were therefore excellent soldier-material. In return for the unusual privilege of exemption from "tributum" (direct taxes on land and heads that most "peregrini" were subject to), they supplied a disproportionate number of recruits to the Julio-Claudian auxilia: one "ala" and eight "cohortes". They also provided most of Augustus' elite personal bodyguard unit ("Germani corpore custodes"), which continued in service until 68 AD. The Batavi auxilia amounted to about 5,000 men, implying that for the entire Julio-Claudian period, over 50% of all Batavi males reaching military age (16 years) may have enlisted in the auxilia. [Birley (2002) 43] Thus the Batavi, although just about 0.05% of the total population of the empire (of "ca." 70 million) in 23 AD, supplied about 4% of the total auxilia "i.e." 80 times their proportionate share. [Scheidel (2006) 9] They were regarded by the Romans as the very best ("fortissimi", "validissimi") of their auxiliary, and indeed all, their forces. [Tacitus "Germania" 29.1 and "Historiae" II.28] In Roman service, they had perfected a technique for swimming across rivers wearing full armour and weapons. [Dio Cassius LXIX.9.6; Tacitus "Agricola" 18.4 ]

Julius Civilis (clearly an adopted Latin name, 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. [Tacitus "Annales" IV.12]

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 false suspicion of treason. His brother was executed, and Civilis sent to Rome in chains for judgement by Nero. [Tacitus "Historiae" IV.13] He was released by Nero's successor, Galba, but the latter also disbanded the imperial bodyguard unit, thus alienating several hundred crack Batavi troops, and indeed the whole Batavi nation who regarded it as a grave insult. [Tacitus "Historiae" II.5] At the same time, relations collapsed between the Batavi cohorts and the legion they had been attached to since the invasion of Britain 25 years earlier ("XIV Gemina"): their mutual hatred erupted in open fighting on at least two occasions. [Tacitus "Historiae" I.64, II.66]

At this juncture, the Roman empire was convulsed by its first major civil war since the Battle of Actium exactly a century earlier. 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. [Tacitus "Historiae" IV.14]

Civilis now led his people in open revolt. Initially, he claimed he was supporting his friend from British days Vespasian's bid for power. But the uprising soon became a bid for independence. [Tacitus "Historiae" IV.13, 18] Civilis took advantage of 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. [Tacitus "Historiae" IV.24, 27] Civilis quickly won the support of the Batavi's neighbours and cousins, 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. [Tacitus "Historiae" IV.15-6] Then two legions sent against Civilis were defeated when their companion Batavi "ala" defected to his side. [Tacitus "Historiae" IV.18] The "classis germanica" (Rhine flotilla), largely manned by Batavi, was seized by Civilis. [Tacitus "Historiae" IV.16] Then a further eight Batavi regiments joined him, defeating a Roman force that attempted to thwart them. [Tacitus "Historiae" IV.20] By now, Civilis commanded at least 6,000 (12 regiments) 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. [Tacitus "Historiae" IV.21, 28] 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. [Tacitus "Historiae" IV.33, 66, 67] He was able to destroy the two remaining legions in Germania Inferior ("V Alaudae" and "XV Primigenia"). [Tacitus Historiae]

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 despatched from Italy, two from Spain and one from Britain) to deal with Civilis. [Tacitus "Historiae" IV.68] Its commander Petillius Cerialis had to fight two difficult battles, at Trier and Xanten, before he could overrun the Batavi's homeland. [Tacitus "Historiae" V] 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. [Tacitus "Historiae" V.26] 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 crack Batavi troops, it is likely that the terms were lenient by Roman standards. [Birley (2002) 44]

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. [Tacitus "Agricola" 35-8] Even as late as 395, units with the Batavi name were classified as elite "palatini" "e.g." "equites Batavi seniores" (cavalry) and "auxilium Batavi seniores" (infantry). ["Notitia Dignitatum" Titles IV and V]

Flavian era (69–96 AD)

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 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. [Goldsworthy (2000) 126] But in the Flavian period (69–96), this appears to have become standard policy. [Keppie (1996) 396] 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. [Mattingly (2006) 132] 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. [Roxan (2003); Holder (2006)] Furthermore, it appears that in the Flavian era native nobles were no longer permitted to command auxiliary units from their own nation. [Keppie (1996) 394]

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. [Keppie (1996) 396] 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. [Mattingly (2006) 168–9]

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"). [Keppie (1996) 391] 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. [Hassall (2000) 332–4]

Later Principate (97–284)

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. [Holder (2003) 145]

At the midway point in this period, there were probably about 380 auxiliary regiments ("ca." 90 "alae" and 290 "cohortes", of which about 200 "equitatae") . At this time, the auxilia probably numbered a total of about 220,000 effectives "i.e." nearly twice the strength in 23 AD. Of the total, about 150,000 were infantry, about 75,000 cavalry. [Holder (2003) 145] This compares with 154,000 legionaries (28 legions of 5,500 men each) at this time, of which just 3,360 were cavalry. (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 five new legions (27,500 men) to a peak of 33. [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)] An equivalent number of auxilia ("i.e." 50–60 new regiments) were probably added, perhaps reaching a peak of "ca." 440 regiments by the end of Septimius Severus's rule (211 AD). [Hassall (2000) 320]

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

* Assuming same pay multiples as equivalent officers in Late Roman army [Elton (1996) 123]

Common soldiers

At the bottom end of the rank pyramid, ordinary soldiers held the official ranks of "pedes" (foot soldier in a "cohors"), "eques" (cavalryman in a "cohors equitata") and "gregalis" ("ala" cavalryman). [Davies (1988) 148]

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. [Goldsworthy (2003) 78, 80]

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. [Holder (1980) 123] From the Flavian era onwards, the auxilia were an all-volunteer force. [Goldsworthy (2003) 76] Although recruits as young as 14 are recorded, the majority of recruits (66%) were from the 18–23 age group. [Holder (1980) 138]

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. [Holder (1980) 123] The regiment would thus lose its original ethnic identity. [Keppie (1996) 396] 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. [Mattingly (2006) 168–9] It also appears that the Danubian provinces (Raetia, Pannonia, Moesia, Dacia) remained key recruiting grounds for units stationed all over the empire. [Military Diplomas Online "Introduction"] [RMD Vol V Appendix 4 e.g. RMD 127, 128]

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. [Mattingly (2006) 190] 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). [Holder (1980) 86–8] 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. [Goldsworthy (2003) 74] [Heather (2005) 119] 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. [Mattingly (2006) 223] [ "List of auxiliary units in Britain"]

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. [Goldsworthy (2003) 94] The same differentials (of about 20% between grades) seem to have existed at the time of Domitian (r. 81-96). [Hassall (2000) 336] 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. [Goldsworthy (2003) 95]

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

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. [Duncan-Jones (1994) 34] 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. [Jones (1964) 647] 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. [Goldsworthy (2003) 96] 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. [Duncan-Jones (1994) 40] 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. [Duncan-Jones (1994) 36]

Junior officers

Officers in the Roman army were known as "principales". Below centurion rank, a cohort's "centuriae" appear to have the same ranks as legionary "centuriae" "i.e." the group of junior officers: "vexillarius" (standard-bearer for the whole regiment, from "vexillum") "optio" (the centurion's deputy), "signifer" (standard-bearer for the "centuria") and "tesserarius" (officer of the watch), in order of rank. 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. [Birley (2002) 47] As in the legions, the junior "principales", together with some regimental specialists, were classified in two general ranks: "duplicarii" ("double-pay men") and "sesquiplicarii" ("one-and-a-half-pay men"). [Goldsworthy (2003) 94] These ranks probably compare most closely, in function and pay levels, with the modern junior ranks of sergeant and corporal.

Besides combat effectives, regiments also contained specialists, some of whom held the ranks of "duplicarius" or "sesquiplicarius", others were common soldiers with the status of "milites 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), "cornicularius" (clerk in charge of all the regiment's records and paperwork). [Birley (2002) 47–8; Vindolanda Tablets Online "Introduction: Personnel"]

Senior officers

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. [Goldsworthy (2003) 73] Those rising from the ranks could be promotions from the legions as well as from the unit'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. [Holder (1980) 86-8] 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 below). [Goldsworthy (2003) 72] 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. [Goldsworthy (2003) 73]

We do not know pay rates for "centuriones" and "decuriones", but these are also believed to have amounted to several times that of a "miles". [Goldsworthy (2003) 72] In the late Roman army, an officer called a "centenarius", which may be the equivalent of the earlier "centurio", was paid 2.5 times the salary of a common soldier. His immediate superior, a "ducenarius" (who according to the unreliable Vegetius commanded 200 men, as the title implies), was paid 3.5 times. [Jones (1964) 634]

Unlike a "legatus legionis" (who had an officer staff of six "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). [Birley (2002) 47]


It appears that in the 2nd century, the majority of auxiliary prefects were still of Italian origin. ["Prosopographia Militiarum Equestrium" Vol V (2001)] In contrast, the evidence for the 3rd century is that Italians provided less than a third of prefects. [Holder (1982) 65] 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 awarded equestrian rank after a year as "primuspilus". [Goldsworthy (2003) 65–6]

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. [Goldsworthy (2003) 65–6] [Goldsworthy (2000) 165]

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). [Birley (2002) 46] (This compares to a full colonel in the British Army, who is currently paid about five times a private's salary). [] 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.

pecialised 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:


"Sagittarii" ("archers", from "sagitta" = "arrow") units recorded in the 2nd century are: eight "alae sagittariorum" (mounted archers), eighteen "cohortes sagittariorum" (foot archers) and six "cohortes sagittariorum equitatae" (mixed foot/mounted archers). These 32 units (of which four were milliary) 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, thirteen have Syrian names, seven Thracian, five from Asia Minor, one from Crete and the remaining six of other or uncertain origin. [Holder (2003) ]

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. [Rossi (1971) 102] The standard bow used by Roman auxilia was the recurved composite bow, a sophisticated, compact and powerful weapon. [Goldsworthy (2003) 137]

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. [Goldsworthy (2003) 137]

Light cavalry

"Equites Maurorum" ("Moorish cavalry", from "equites" = "horsemen") still came from Mauretania and Numidia, whose inhabitants, the Mauri (from whom derives the English term "Moors"), were the ancestors of the Berber people of modern Algeria and Morocco. On Trajan's Column, Mauri horsemen are shown riding bare-back with a simple halter to control their mounts. They wear no armour, just a short tunic. Their weaponry cannot be discerned due to stone erosion, but probably consisted of short spears. The riders are depicted with long hair in dreadlocks. [Rossi (1971) 104] It is unclear what proportion of the Moorish cavalry were regular auxilia units as opposed to irregular "foederati" units. [Campbell (2003) 212]


"Funditores", ("slingers", from "funda" = "sling") units do not appear in the epigraphic record. [Goldsworthy (2003) 137] 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"). [Rossi (1971) 102] The late Roman army of the 4th century contained at least one independent "funditores" unit. [Elton (1996) 105]

Heavily-armoured lancers

"Contarii" ("lancers", from "contus" = a heavy long lance) were a type of special heavy cavalry, covered from head to toe in scalar armour. Their numbers were probably considerably expanded in the 3rd century. Based on Sarmatian and Parthian models, they were called "contarii", "cataphractarii" and "clibanarii". Together with new units of light mounted archers, they 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 them with a charge by the "cataphractarii". [Goldsworthy (2000) 140] 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. [Holder (2003) 135, 133]

Imperial horse guards

"Equites singulares Augusti" ("personal cavalry of the emperor", from "singuli" = "attached to one individual"), was a unit made up of the best cavalry the auxilia could offer. Their core component were crack Batavi horsemen. [Birley (2002) 43] This was the only unit of the Praetorian Guard which recruited non-citizens. Starting as a milliary "ala" (720-strong), it grew steadily in size, reaching 2,000 men at end 2nd century. They would always accompany the emperor on tours of the provinces and campaigns. [Goldsworthy (2003) 58] In addition to the "ala" at Rome, it appears that after some campaigns, detachments of "singulares" were permanently left behind in the provinces, becoming regular "alae", but retaining the prestigious "singulares" title and crack reputation "e.g." "Ala I Flavia singularium" stationed in Raetia in mid 2nd century. On Trajan's Column, "singulares" are easily identifiable because they always accompany the Emperor himself, and are not dressed for battle: they do not wear a cuirass, but marching clothes (tunics and cloaks). Their standards carry the same lightning-and-thunderbolt motif (with or without wings) as the legions. [Rossi (1971) 102]

Camel troops

"Dromedarii" ("camel-mounted troops") had just one one of these is attested from the 2nd century, "ala I Ulpia dromedariorum milliaria" in Syria. [Holder (2003) 140]


"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. [Mattingly (2006) 223]

Mixed cohort cavalry

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. [Cheesman (1914)] This view is today discredited. Although it is clear that "equites cohortales" did not match "equites alares" 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". [Davies (1988) 141-3]

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") or "foederati" (treaty troops from "foedus", "treaty") Due to scarce evidence, we do not know how many such units existed, when or for how long.

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. [Rossi (1971) 104.] 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 [Dio Cassius LXXI.16]

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. [Holder (1980) Chapter 2]


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"). [Goldsworthy (2003) 97]


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. [Goldsworthy (2003) 96]

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." [Goldsworthy (2003) 97] .

Everyday life

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. [Vindolanda Tablets 166-177] Records were kept on all individual soldiers and there is evidence of filing systems. [Goldsworthy (2003) 90] From what has been discovered at Vindolanda, it can be deduced that the garrison in Britain alone generated tens of millions of documents. [Mattingly (2006) 200]

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. [Mattingly (2006) 162]

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. [Mattingly (2006) 163]

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. [Vindolanda Tablet 154] 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. [Davies (1988) 146] Combat training and exercises were a central part of an auxiliary's weekly routine. One tablet probably contains a scathing comment of 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 properly or throw their javelins without losing their balance". [Vindolanda Tablet 164 (my translation)] 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" [Vindolanda Tablet 242] ). 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. [Goldsworthy (2003) 92] 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", "legatus Augusti" or even the emperor himself. [Davies (1988) 146]

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) [Vindolanda Tablet 154] . 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. ["Renuntia" displayed in Goldsworthy (2003) 145] 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. [Vindolanda Tablets 182, 343] 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. [Vindolanda Tablets 155, 180, 182, 183, 184, 207, 309] Some soldiers with special skills were given the status of "immunes", meaning they were exempt from normal duties and chores so they could practice their specialism. 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). [Birley (2002) 48] It is uncertain, however, whether these jobs were all held by "milites immunes" or some by civilians working for the unit on contract. [Vindolanda Tablets Online "Introduction: Soldiers and Civilians"]


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 them for big projects, if the security situation in the province allowed, than to hire private contractors. Soldiers naturally built forts and fortifications: 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). [Goldsworthy (2003) 146-8] 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) [D.J. Thompson in Wacher (1988) 557] . Most of the available evidence relates to legionary construction. But the Vindolanda tablets attest auxiliaries' construction activity: 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. [Vindolanda Tablets 155, 258] The Roman military also operated many of the mines and quarries that produced the raw materials they needed for weapons and armour manufacture and for construction. Soldiers would supervise the slave-gangs that generally acted as miners, or mine themselves at times of urgent demand. [Goldsworthy (2003) 249]

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. [Burton (1988) 424-6] They therefore relied on their troops for many such duties: escorting the governor or other senior officials, patrolling highways, assisting and escorting tax collectors, carrying official despatches, arresting wanted men. [Goldsworthy (2003) 149] Thus a "renuntia" shows a detachment of 46 men of "I Tungrorum" on escort duty ("singulares") with the provincial governor's staff. [Vindolanda Tablet 154]

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). [Goldsworthy (2003) 91] These stations may well be the six unidentified locations where small detachments of "ca." ten men, each under a centurion, were deployed according to a "renuntia" of "cohors I Tungrorum". [Vindolanda tablet 154] They would check the identities and cargoes of road users and keep the highways clear of robbers: one "eques" of "I Hispanorum veterana" was reported killed by robbers in a "renuntia". ["Renuntia" displayed in Goldsworthy (2003) 145] They 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. [Burton (1988) 428] Despatch riders ("dispositi"), normally "equites cohortales", would also be stationed at "mutationes" to form relays to carry messages rapidly between forts. [Davies (1988) 146] Relays of fresh riders and horses, careering at full gallop, could maintain an average speed of 30 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. [Using average speeds achieved by the Pony Express in the American West, 19th century]

Social life

All the Vindolanda documents are written by officers, supporting the view that many of the lower ranks may have been illiterate. [Goldsworthy (2003) 73] 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. [Vindolanda Tablet 346] 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"). [Vindolanda Tablets 166, 311] 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. [Vindolanda Tablets 311, 174, 213]


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. [Pliny "De Historia Naturali" XXX.4] Also banned was Christianity. As it was monotheistic, its followers refused to pay homage to the "imagines" (cult portraits) of ruling and past emperors, an act considered treasonous by the Romans. [Pliny the Younger "Letters" X.9] In theory, soldiers were only permitted to honour such non-Roman gods which 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 "e.g." Mars Toutates, the assimilation of a Gallic deity to the Roman god of war. [Mattingly (2006) 484] All dedications were supposed to quote either the Roman name alone or the joint Roman/non-Roman name. But in practice, little effort was made by senior officers to enforce these rules. 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. [Mattingly (2006) 214-6]

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. [Goldsworthy (2003) 108]

Outside of the regimental ceremonies, auxiliary soldiers revered a vast array of deities. [Goldsworthy (2003) 110] 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). [Mattingly (2006) 215]

From the 2nd century onwards, Eastern mystery cults spread widely in the empire. The most popular among the military was Mithraism, based on the Iranian god Mithra (although the cult as observed in the empire may have differed greatly from its original). Based on secret initiation ceremonies and rites, this cult is attested, for example, by the discovery of a Mithraeum (Mithraic temple) at Carrawburgh. It is likely that its membership was limited because of the limited space for religious ceremonies. Membership, according to the written evidence of dedications in Nida (Heddernheim), was not restricted according to social standing. [Goldsworthy (2003) 112-3] [Meier-Arendt "Römische Steindenkmäler aus Frankfurt am Main", Museum für Vor- und Frühgeschichte Frankfurt, Archäologische Reihe 1(1983)] Another eastern mystery cult, Christianity, was much less common amongst the military until it became predominant in the 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. But it may have had clandestine followers in the military, especially in the East, where it spread widely in the 2nd and 3rd centuries. [Goldsworthy (2003) 212] The discovery of a Christian house church with the earliest Christian paintings extant at the fortress town of Dura-Europos in Syria dating to the early 3rd century may indicate a Christian element in that town's garrison. [S. James "Dura-Europos:Pompeii of the Desert" 4]

Deployment in the 2nd century

# The auxiliary unit figures above include units attested in the Hadrianic period, units attested both before and after the period and thus certain to have existed in it and 14 units attested shortly before the period and thus not certain, but likely to have existed then. The 2nd century is by far the best documented period for the auxilia, mainly due to the abundance of military diplomas found. But the names of regiments never previously known are occasionally discovered in new diploma evidence "e.g." the "ala Augusta Xoitana", first published in "Roman Diplomas V". [Holder (2006)] In addition, some regiments attested in the 1st century or in the 3rd may have also existed in the 2nd, although the evidence has yet to be found.
# For calculation of cavalry numbers, it is assumed that 70% of "cohortes" are "equitatae" "i.e." contained a cavalry contingent. It is uncertain what proportion of "cohortes" were "equitatae" ("i.e." possessed a cavalry contingent). Figures given in "CAH" XI show that 50% of cohorts have been positively identified as "equitatae". [Hassall (2000) 332] But cohorts not carrying the "equitata" title have been found to contain cavalry "e.g." by discovery of a tombstone of a cavalryman attached to the cohort. Holder suggests as many as 70% may have been in the time of Hadrian (117–138) and that even this may be an underestimate. [Holder (2003) 119] Its own cavalry would obviously give the cohort far more flexibility in the range of operations it could carry out independently. A "cohors equitata" was in effect a self-contained mini-army. [Goldsworthy (2003) 168]
# The table shows the importance of auxiliary troops in the 2nd century, when they outnumbered legionaries by 1.5 to 1.
# The table shows that legions did not have a standard complement of auxiliary regiments [Goldsworthy (2000)] 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.
# 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%.
# The figures show the massive deployments in Britannia and Dacia. Together, these two provinces account for 27% of the total auxilia corps.

ee also

* List of Roman auxiliary regiments
* Structural History of the Roman military
* Roman Army
* Auxiliaries in Britain (Roman military)




* Arrian "Acies contra Alanos" (early 2nd c.)
* Dio Cassius "Roman History" (mid 3rd c.)
* Suetonius "De vita Caesarum" (early 2nd c.)
* Tacitus "Agricola" (end of 1st c.)
* Tacitus "Annales" (end of 1st c.)
* Tacitus "Historiae" (end of 1st c.)
* Vegetius "De re militari" (late 4th c.)



External links

* [ Roman Military Diplomas Online]
* [ Batavian auxiliaries re-enactors]
* [ List of auxiliary units in Britain]
* [ Vindolanda Tablets Online]

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