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The Late Roman army is the term used to denote the military forces of the Roman Empire from the accession of Emperor Diocletian in 284 until the Empire's definitive division into Eastern and Western halves in 395. A few decades afterwards, the Western army disintegrated as the Western empire collapsed. The East Roman army, on the other hand, continued intact and essentially unchanged until its reorganization by themes and transformation into the Byzantine army in the 7th century. The term "late Roman army" is often used to include the East Roman army.

The army of the Principate underwent a significant transformation as a result of the chaotic 3rd century. Unlike the Principate army, the army of the 4th century was heavily dependent on conscription and its soldiers were more poorly remunerated than in the 2nd century. Barbarians from outside the empire probably supplied a much larger proportion of the late army's recruits than in the army of the 1st and 2nd centuries. There is no evidence, however, that barbarian recruitment damaged the army's effectiveness.

The army of the 4th century was probably no larger than that of the 2nd. The main change in structure was the establishment of large armies that accompanied the emperors (comitatus praesentales) and were generally based away from the frontiers. Their primary function was to deter usurpations. The legions were split up into smaller units comparable in size to the auxiliary regiments of the Principate. In parallel, legionary armour and equipment were abandoned in favour of auxiliary equipment. Infantry adopted the more protective equipment of the Principate cavalry.

The role of cavalry in the late army does not appear to have been enhanced as compared with the army of the Principate. The evidence is that cavalry was much the same proportion of overall army numbers as in the 2nd century and that its tactical role and prestige remained similar. Indeed, the cavalry acquired a reputation for incompetence and cowardice for their role in three major battles in mid-4th century. In contrast, the infantry retained its traditional reputation for excellence.

The 3rd and 4th centuries saw the upgrading of many existing border forts to make them more defensible, as well as the construction of new forts with much higher defensive specifications. The interpretation of this trend has fuelled an ongoing debate whether the army adopted a defence-in-depth strategy or continued the same posture of "forward defence" as in the early Principate. Many elements of the late army's defence posture were similar to those associated with forward defence, such as forward location of forts, frequent cross-border operations, and external buffer-zones of allied barbarian tribes. Whatever the defence strategy, it was apparently less successful in preventing barbarian incursions than in the 1st and 2nd centuries. This may have been due to heavier barbarian pressure, and/or to the practice of keeping large armies of the best troops in the interior, depriving the border forces of sufficient support.

Sources

Much of our evidence for 4th century army unit deployments is contained in a single document, the Notitia Dignitatum, compiled ca. 395–420, a manual of all late Roman public offices, military and civil. The main deficiency with the Notitia is that it lacks any personnel figures so as to render estimates of army size impossible. Also, it was compiled at the very end of the 4th century; it is thus difficult to reconstruct the position earlier. However, the Notitia remains the central source on the late Army's structure due to the dearth of other evidence.^[1]

The main literary sources for the 4th century army are the Res Gestae (History) of Ammianus Marcellinus, whose surviving books cover the period 353 to 378. Marcellinus, himself a veteran soldier, is regarded by scholars as a reliable and valuable source. But he largely fails to remedy the deficiencies of the Notitia as regards army and unit strength or units in existence, as he is rarely specific about either. The third major source for the late army is the corpus of imperial decrees published in the East Roman empire in the 5th and 6th centuries: the Theodosian code (438) and the Corpus Iuris Civilis (528–39). These compilations of Roman laws dating from the 4th century contain numerous imperial decrees relating to all aspects of the regulation and administration of the late army.

De re militari, a treatise on Roman military affairs by Vegetius, a late 4th century writer, contains considerable information on the late army, although its focus is on the army of the Republic and Principate. However, Vegetius (who wholly lacked military experience) is often unreliable. For example, he stated that the army abandoned armour and helmets in the later 4th century (offering the absurd explanation that this equipment was too heavy), which is contradicted by sculptural and artistic evidence.^[2] In general, it is not safe to accept a Vegetius statement unless it is corroborated by other evidence.

Scholars of the late army have to contend with a dramatic diminution of the epigraphic record in the 3rd and 4th centuries, compared with the 1st–2nd centuries. Diplomas were no longer issued to retiring auxiliaries after 203 (most likely because almost all were already Roman citizens by then). In addition, there was a huge reduction in the number of tombstones, altars and other dedications by Roman servicemen. Official stamps of military units on building materials (e.g. tiles) are much rarer. But this trend should probably not be seen as indicating a decline in the army's administrative sophistication. Papyrus evidence from Egypt shows that military units continued to keep detailed written records in the 4th century (the vast bulk of which are lost due to organic decomposition). Most likely, the decline in inscriptions is due to changing fashion, in part influenced by the increase in barbarian recruits and the rise of Christianity.^[3] The dearth of inscriptions leaves major gaps in our understanding of the late army and renders many conclusions tentative.

Evolution of the 4th century army

Background: the Principate army

The regular army of the Principate was established by the founder–emperor Augustus (ruled 30 BC – 14 AD) and survived until the end of the 3rd century. The regular army consisted of two distinct corps, both being made up of mainly volunteer professionals.

The elite legions were large infantry formations, varying between 25 and 33 in number, of ca. 5,500 men each (all infantry save a small cavalry arm of 120) which admitted only Roman citizens.^[4] The auxilia consisted of around 400 much smaller units of ca. 500 men each (a minority were up to 1,000 strong), which were divided into approximately 100 cavalry alae, 100 infantry cohortes and 200 mixed cavalry/infantry units or cohortes equitatae.^[5] Some auxilia regiments were designated sagittariorum, meaning that they specialised in archery. The auxilia thus contained almost all the Roman army's cavalry and archers, as well as (from the late 1st century onwards) approximately the same number of foot soldiers as the legions.^[6] The auxilia were mainly recruited from the peregrini: provincial subjects of the empire who did not hold Roman citizenship, but the auxilia also admitted Roman citizens and possibly barbari, the Roman term for peoples living outside the empire's borders.^[7] At this time both legions and auxilia were almost all based in frontier provinces.^[8] The only substantial military force at the immediate disposal of the emperor was the elite Praetorian Guard of 10,000 men which was based in Rome.^[9]

The senior officers of the army were, until the 3rd century, mainly from the Italian aristocracy. Members of the senatorial order, the highest echelon, exclusively filled the following posts:

(a) legatus Augusti (provincial governor, who commanded military forces in the province as well as heading the civil administration)

(b) legatus legionis (legion commander)

(c) tribunus militum laticlavius (legion deputy commander).^[10]

The equites (or "knights"), the second order of nobility, provided:

(a) the governors of Egypt and a few minor provinces

(b) the two praefecti praetorio (commanders of the Praetorian Guard)

(c) a legion's praefectus castrorum (3rd-in-command) and its remaining five tribuni militum (senior staff officers)

(d) the praefecti (commanders) of the auxiliary regiments.^[11]

Although the two aristocratic orders were hereditary, they were not closed to outsiders. Commoners could be elevated to equestrian rank, and equites to senatorial rank, by decree of the emperor, issued in his capacity as Roman censor. Elevation was usually granted only to those who met the minimum property qualification for each order, which was set by Augustus at 250,000 denarii for senators and at 100,000 denarii for equites (For comparison, a 1st century legionary's gross pay was 250 denarii per annum). Apart from the higher property requirement, it was far more difficult for a family to enter the senatorial order because the head of the family needed first to win a seat in the Senate itself, whose membership was limited to 600 life peers and where, as a consequence, only a few vacancies became available each year. Equites, whose numbers were unrestricted, thus greatly outnumbered senatorians. Already wealthy to start with, the aristocracy accumulated even greater riches by their monopoly of the senior posts in the administration, which carried enormous salaries (and also opportunities for peculation). The senatorial governor of Africa Proconsularis province was paid 250,000 denarii, the same each year as the entire property qualification for his order, whilst the praefectus of an auxiliary cohort was paid ca. 50 times as much as a common foot soldier.^[12][13] Senatorians were prohibited from engaging in commerce, which was considered beneath their status, and therefore invested all their wealth in land. Vast land portfolios, often spread across multiple provinces of the empire, were established. For example, in the time of emperor Nero (54-68), half of the cultivable land of Africa province, then among the most productive agriculturally, was owned by just six senators.^[14] Equites, who were unrestricted, invested not only in land, but also in commercial enterprises: tax collection, shipping and overland transport, mines, construction and manufacturing industry. The Roman aristocracy thus monopolised political, military and economic power.

Hereditary senators and equites normally combined military service with civilian posts, a career path known as the cursus honorum, typically starting with a period of junior administrative posts in Rome, followed by 5–10 years in the military and a final period of senior positions in the either the provinces or Rome.^[15] This tightly-knit ruling oligarchy achieved a remarkable degree of political stability. During the first 200 years of its existence (30 BC - 180 AD), the empire suffered only one major episode of civil strife (the Civil War of 68-9). Otherwise, usurpation attempts by provincial governors were very few and swiftly suppressed.

But already by the late 1st century, an alternative aristocracy, non-Italian and military, was becoming established. This was a result of the practice whereby the emperor customarily elevated the primuspilus (chief centurion) of each legion to equestrian rank on completion of his year in office. This resulted in some 30 career soldiers, mostly non-Italian and risen from the ranks, joining the aristocracy each year.^[16]

3rd century developments

The seminal development for the army in the early 3rd century was the Constitutio Antoniniana (Antonine Decree) of 212, issued by Emperor Caracalla (ruled 211–18). This granted Roman citizenship to all free inhabitants of the empire, ending the second-class status of the peregrini.^[17] This had the effect of breaking down the distinction between the citizen legions and the auxiliary regiments. In the 1st and 2nd centuries, the legions were the symbol (and guarantors) of the dominance of the Italian "master nation" over its subject peoples. In the 3rd century, they were no longer socially superior to their auxiliary counterparts (although they may have retained their elite status in military terms) and the legions' special armour and equipment (e.g. the lorica segmentata) was phased out.^[18]

The traditional alternation between senior civilian and military posts fell into disuse in the 2nd and 3rd centuries, as the Italian hereditary aristocracy was progressively replaced in the senior echelons of the army by the primipilares (former chief centurions).^[19] In the 3rd century, only 10% of auxiliary prefects whose origins are known were Italian equestrians, compared to the majority in the previous two centuries.^[20] At the same time, equestrians increasingly replaced the senatorial order in the top commands. Septimius Severus (ruled 197–211) placed equestrian primipilares in command of the three new legions he raised and Gallienus (260–68) did the same for all the other legions, giving them the title praefectus pro legato ("prefect acting as legate").^[21][22] The rise of the primipilares may have provided the army with more professional leadership, but it resulted in a major increase in military rebellions by ambitious generals seeking supreme power. The 3rd century saw numerous coups d'etat and destructive civil wars. Few 3rd century emperors enjoyed long reigns or died of natural causes.^[23]

Emperors responded to the increased insecurity with a steady build-up of the forces at their immediate disposal. These became known as the comitatus ("escort", from which derives the English word "committee"). To the Praetorian Guard's 10,000 men, Septimius Severus added the legion II Parthica. Based at Albano Laziale near Rome, it was the first legion to be stationed in Italy since Augustus. In addition, he doubled the size of the imperial escort cavalry, the equites singulares Augusti, to 2,000 by drawing select detachments from alae on the borders.^[24] In total, his comitatus numbered some 17,000 men, equivalent to 31 infantry cohortes and 11 alae of cavalry.^[25] The trend for the emperor to gather round his person ever greater forces reached its peak in the 4th century under Constantine I the Great (ruled 312–37), whose comitatus may have reached 100,000 men, perhaps a quarter of the army's total effective strength.^[26]

The rule of Gallienus saw the appointment of a senior officer, with the title of dux (plural form: duces, the origin of the medieval noble rank of duke), to command all the comitatus cavalry. This force included some contingents of equites promoti (cavalry contingents detached from the legions), plus some apparently new Dalmatian light cavalry (equites Dalmatarum) and elements of allied barbarian cavalry (equites foederati).^[27] Under Constantine I, the head of the comitatus cavalry was given the title of magister equitum ("master of horse"), which in Republican times had been held by the deputy to a Roman dictator.^[28] But neither title implies the existence of an independent "cavalry army", as was suggested by some more dated scholars. The cavalry under both officers were integral to mixed infantry and cavalry comitatus, with the infantry remaining the predominant element.^[25]

The 3rd century saw a progressive reduction in the size of the legions and even some auxiliary units. Legions were broken up into smaller units, as evidenced by the shrinkage and eventual abandonment of their traditional large bases, in Britain for example.^[29] In addition, from the 2nd century onwards, the separation of some detachments from their parent units became permanent in some cases, establishing new unit types, e.g. the vexillatio equitum Illyricorum based in Dacia in the early 2nd century^[30] and the equites promoti^[31] and numerus Hnaufridi in Britain.^[32] This led to the proliferation of unit types in the 4th century, generally of smaller size than those of the Principate. For example, in the 2nd century, vexillatio (from vexillum = "standard") was originally a generic term meaning any detachment from a legion or auxiliary regiment, either cavalry or infantry. In the 4th century, it denoted an elite cavalry regiment.^[33]

In the 3rd century, a small number of regular units are recorded as bearing the names of barbarian tribes (as opposed to peregrini tribal names) for the first time. These were clearly foederati (allied troops under a military obligation to Rome) converted into regular units, a trend that was to accelerate in the 4th century.^[34] The ala I Sarmatarum, for example, based in Britain, was probably composed of some of the 5,500 captured Sarmatian horsemen sent to garrison Hadrian's Wall by emperor Marcus Aurelius in ca. 175.^[35] There is no evidence of irregular barbarian units becoming part of the regular Principate army until the 3rd century.^[36]

3rd century crisis

Roman emperor Valerian I (left, kneeling) begs for his life after being captured by Persian Shah Shapur I (mounted) at the Battle of Edessa (259), the most humiliating of the military disasters suffered by the empire in the late 3rd c. According to one account, Valerian was in subsequent years forced to serve as the Shah's human footstool whenever he mounted his horse. This duty was considered a great honour by the Persians, and normally reserved for the highest-ranking noblemen. But it was certainly not seen as such by contemporary Roman opinion. Rock-cut bas-relief at Naqsh-e Rostam near Shiraz, Iran

The mid-3rd century saw the empire plunged into a military and economic crisis which almost resulted in its disintegration. It consisted of a series of military catastrophes in 251–271 when Gaul, the Alpine regions and Italy, the Balkans and the East were simultaneously overrun by Alamanni, Sarmatians, Goths and Persians respectively.^[37] 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 (268–70).^[38] The evidence for the earlier Antonine pandemic of the late 2nd century, also smallpox, indicates a mortality of 15–30% in the empire as a whole.^[39] Zosimus describes the Cyprianic outbreak as even worse.^[40] 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.^[41]

The 3rd century crisis started a chain-reaction of socio-economic effects that proved decisive for the development of the late army. The combination of barbarian devastation and reduced tax-base due to plague bankrupted the imperial government, which resorted to issuing ever more debased coin e.g. the antoninianus, the silver coin used to pay the troops in this period, lost 95% of its silver content between its launch in 215 and its demise in the 260s.^[42] (In other words, by the end of the period, the government was able to issue 20 times the quantity of antoniniani with the same amount of precious metal). This inevitably led to rampant price inflation. For example, the price of wheat under Diocletian was 67 times the typical Principate figure.^[43] The monetary economy collapsed and the army was obliged to rely on unpaid food levies to obtain sufficient supplies.^[44] Food levies were raised when and where required, without regard to fairness, ruining the border provinces where the military was mainly based.^[45] Soldiers' salaries became virtually worthless, reducing the army's recruits, once well-paid with plenty of disposable income, to a subsistence-level existence little better than that endured by their peasant families.^[46] This in turn discouraged volunteers and forced the government to rely on conscription to find enough recruits.^[47] But even this was not sufficient to plug the recruitment shortfalls caused by the plague. The only solution was large-scale recruitment of barbarians into the regular army. By the mid-4th century, barbarian-born men probably accounted for about a quarter of all recruits (and over a third in elite regiments), likely a far higher share than in the 1st–2nd centuries.^[48]

Illyrian military junta

The Illyrian emperor Claudius II (r. 268–70), whose annihilating victories over the barbarian invaders of the empire saved it from collapse. Claudius was the first in a line of Illyrian emperors that were to rule the empire for a century. Debased silver antoninianus

Emperor Aurelian (270–75), who completed Claudius' expulsion of barbarian invaders from the empire. Bronze antoninianus, Siscia mint

The Aurelian Walls of Rome, built by Aurelian in 270-5. Rome's first new wall since the construction of the Servian Wall after the Gauls sacked Rome 650 years earlier, they symbolised the pervasive insecurity of the 3rd century empire. Original height: 8m (25 ft). Doubled in 410 to 16m (52 ft) after second sack of Rome in 410. Both walls and towers were originally crenellated, but this has only survived in small sections. Most of the 19km circuit still stands today

The emperor Diocletian (ruled 284–305), who launched wide-ranging reforms of the Roman army and government. Bronze follis coin

The Tetrarchs: Diocletian and his three colleagues. To the left, the two Augusti (co-emperors), to the right the two Caesars (deputy emperors). Note the "Pannonian-style" caps commonly worn (out of combat) by officers in the late army as a result of the pervasive influence of the Illyrian officer class; and the sword grips with eagle-head pommels. Porphyry statue on Basilica di San Marco, Venice

The emperor Constantine I (ruled 312–37), who established the first large-scale comitatus (imperial escort army) and divided the army into escort army (comitatenses) and border (limitanei) troops, giving the late Roman army the structure described in the Notitia Dignitatum. Bust in Musei Capitolini, Rome

The Illyrian-speaking tribes that dominated the Roman provinces of Pannonia, Dalmatia and Moesia Superior, and included mountain tribes of semi-nomadic pastoralists such as the Dalmatae and Breuci, had a fearsome reputation as warriors.^[49] They were seen as excellent soldier material. From the time of Domitian (ruled 81–96), when over half the Roman army was deployed in the Danubian regions, the Illyrian provinces became the most important recruiting ground of the auxilia and later the legions.^[50] In the 3rd century, Romanised Illyrians, mostly primipilares and their descendants, came to dominate the army's senior officer echelons.^[51]

Finally, the Illyrian officer class seized control of the state itself. In 268, the emperor Gallienus (ruled 260–68) was overthrown by a coup d'état organised by a clique of Illyrian senior officers, including his successors Claudius II Gothicus and Aurelian (270–75).^[52] They and their successors Probus (276–78) and Diocletian (ruled 284–305) and his colleagues in the Tetrarchy formed a sort of self-perpetuating military junta of Illyrian officers who were born in the same provinces (several in the same city, Sirmium, a major legionary base in Moesia Superior) or had served in the same regiments.^[50]

The junta succeeded in reversing the military disasters of 251–71 with a string of brilliant victories, most notably the defeat inflicted at Naissus on a vast Gothic army by Claudius II, which was so crushing that the Goths did not seriously threaten the empire again until a century later at Adrianople (378).^[53]

The Illyrian emperors continued to rule the empire until 379. Indeed, until 363, power was held by descendants of one of the original junta members. Constantine I' s father, Constantius Chlorus was a Caesar (deputy emperor) in Diocletian's Tetrarchy.^[54] His grandson Julian ruled until 363. The Illyrian emperors restored the army to its former strength and effectiveness. But they had a narrow political focus, solely concerned with the needs and interests of the military. They were also divorced from the immensely wealthy Roman senatorial families that continued to dominate the Senate and owned much of the empire's land. This in turn bred a feeling of alienation from the army among the Roman aristocracy which in the later 4th century began to resist the military's exorbitant demands for recruits and supplies.^[55]

Diocletian

Diocletian's wide-ranging administrative, economic and military reforms were entirely aimed at providing the military with sufficient resources, both in manpower and supplies.^[56] In the words of one historian, "Diocletian ... turned the entire empire into a regimented logistic base" (to supply the army).^[57]

To this end, Diocletian instituted the system of indictiones (tax demands issued in advance of the tax cycle), with the amount of tax demanded related to the amount of cultivated land in each province, aimed at making more efficient and more equitable the collection of taxes in kind. To deal with the problem of rural depopulation (and consequent loss of food production), he decreed that peasants must register in their home locality and never leave it.^[58]

To ensure the army received sufficient recruits, Diocletian appears to have instituted systematic annual conscription for the first time since the days of the Roman Republic. In addition he is probably responsible for the decree, first recorded in 313, obliging the sons of serving soldiers (and officers) or veterans to enlist.^[59]

Under Diocletian, the number of legions, and probably of other units, appears to have more than doubled.^[60] But it is unlikely that overall army size increased nearly as much, since unit strengths appear to have been reduced, in some cases drastically.^[61][62] Even so, it is generally agreed that Diocletian increased army numbers substantially. But this was probably from a much lower base than its Severan peak of ca. 440,000, as the army presumably shrank sharply as a result of plague and military disasters in the late 3rd century.^[63] The evidence is that Diocletian restored its strength to at least that of the early 2nd century (ca. 390,000).^[64] But even more than restoring the size of the army, Diocletian's efforts and resources were focused on a massive upgrading of the defensive infrastructure along all the empire's borders, including new forts and strategic military roads.^[65]

Diocletian and his three colleagues each had a comitatus at their disposal. But under Diocletian, these remained informal and small in size and relied on reinforcements from frontier forces for major operations.^[66] Nevertheless, added together, they must have constituted a significant force.

Diocletian's administrative reforms had the twin aims of ensuring political stability and providing the bureaucratic infrastructure needed to raise the recruits and supplies needed by the army.

At the top, Diocletian instituted the Tetrarchy. This divided the empire into two halves, East and West, each to be ruled by an Augustus (emperor); each Augustus would in turn appoint a deputy called a Caesar, who would act both as his second-in-command and designated successor. This four-man team would thus have the flexibility to deal with multiple and simultaneous challenges, while also providing a legitimate succession.^[67]

Diocletian reformed the provincial administration, establishing a three-tiered provincial hierarchy, in place of the previous single-tier structure. The original 42 Principate provinces were almost tripled in number to ca. 120. These were grouped into 12 divisions called dioceses, each under a vicarius, in turn grouped into four praetorian prefectures, to correspond to the areas of command assigned to the four Tetrarchs, who were each assisted by a praefectus praetorio (not be confused with the commanders of the Praetorian Guard). The aim of this fragmentation of provincial administration was probably to reduce the possibility of military rebellion by governors (by reducing the forces they each controlled).^[68]

Also to this end, Diocletian divorced military from civil command in some cases. The old legatus Augusti (governor) of the Principate had combined the role of administrative head with that of commander-in-chief of forces in his province. Now, command of troops in some provinces was entrusted to purely military officers called duces limitis ("border commanders"). However, this was not universally applied. In many provinces, the governor remained in command. In any case, both duces and governors continued to be commanded by their vicarius and praefectus praetorio.^[69] Diocletian completed the exclusion of the senatorial class, still dominated by the Italian aristocracy, from all senior military commands and all top administrative posts except in Italy.^[70]

Ironically, Diocletian's administrative reforms may have worked against the army's best interests by entrenching a largely conscript army. The reforms led to explosive growth in the size of the imperial bureaucracy. The Principate had been a remarkably slimline administration, with just 250 senior officials running the vast empire, relying on local government and private contractors to deliver the necessary taxes and services. By the time of the Notitia, comparable positions had grown to ca. 6,000, a 24-fold increase.^[71] Admittedly, late high officials were paid far less than in the Principate, perhaps an average of a tenth as much.^[72] Nevertheless, the late bureaucracy would still have been around two and a half times as expensive overall, swallowing resources which would probably have been sufficient to bring soldiers' pay back to 2nd-century levels.^[73] The lower pay of the 4th century obliged the army to rely on often reluctant or poor-quality conscripts rather than attracting better-grade volunteers as in the Principate.

Constantine

Constantine I probably completed the replacement of provincial governors as commanders of military units in their provinces by duces. The praefecti praetorio lost their military command and became purely administrative officials, whose central and vital role was to ensure that the armies in their circumscription were properly supplied.^[74]

After defeating Maxentius in 312, Constantine disbanded the Praetorian Guard, ending the latter's 300-year existence.^[75] Although the instant reason was the Guard's support for his rival Maxentius, a force based in Rome had also become obsolete since emperors now rarely resided there. The imperial escort role of the Guard's cavalry, the equites singulares Augusti, was now fulfilled by the scholae. These elite cavalry regiments existed by the time of Constantine and may have been founded by Diocletian.^[76]

Constantine expanded his comitatus into a major and permanent force. This was achieved by the addition of units withdrawn from the frontier provinces and by creating new units: more cavalry vexillationes and new-style infantry units called auxilia. The expanded comitatus was now placed under the command of two new officers, a magister peditum to command the infantry and magister equitum for cavalry (after Constantine's death, these titles became interchangeable, with both officers commanding mixed infantry/cavalry forces). Comitatus troops were now formally denoted comitatenses to distinguish them from the frontier forces (limitanei).^[77] The size of the Constantinian comitatus is uncertain. But Constantine mobilised 98,000 troops for his war against Maxentius, according to Zosimus.^[78] It is likely that most of these were retained for his comitatus.^[79] This represented about a quarter of the total regular forces, if one accepts that the Constantinian army numbered around 400,000.^[80] The rationale for such a large comitatus has been debated among scholars. A traditional view sees the comitatus as a strategic reserve which could be deployed against major barbarian invasions that succeeded in penetrating deep into the empire or as the core of large expeditionary forces sent across the borders. But more recent scholarship has viewed its primary function as insurance against potential usurpers.^[81] (See Strategy below).

In addition, Constantine appears to have reorganised the border forces along the Danube, replacing the old-style alae and cohortes with new units of cunei (cavalry) and auxilia (infantry) respectively.^[82] It is unclear how the new-style units differed from the old-style ones, but those stationed on the border (as opposed to those in the comitatus) may have been smaller, perhaps half the size.^[83] In sectors other than the Danube, old-style auxiliary regiments survived.^[84]

The 5th-century historian Zosimus strongly criticised the establishment of the large comitatus, accusing Constantine of wrecking his predecessor Diocletian's work of strengthening the border defences: "By the foresight of Diocletian, the frontiers of the Roman empire were everywhere studded with cities and forts and towers... and the whole army was stationed along them, so it was impossible for the barbarians to break through... But Constantine ruined this defensive system by withdrawing the majority of the troops from the frontiers and stationing them in cities which did not require protection."^[85]

Zosimus' critique is probably excessive, both because the comitatus already existed in Diocletian's time and because some new regiments were raised by Constantine for his expanded comitatus, as well as incorporating existing units.^[86] Nevertheless, the majority of his comitatus was drawn from existing frontier units.^[87] This drawdown of large numbers of the best units inevitably increased the risk of successful large-scale barbarian breaches of the frontier defences.^[88]

It was probably this factor that led to the emergence of comitatus based in frontier regions (the regional comitatus), distinct from the comitatus praesentales escorting the emperor(s). From the defeat of the usurper Magnentius in 353, there appears to have always been a comitatus in Gaul and one in the East, each under a magister equitum, and one in Illyricum under a senior comes (rei militaris) (plural form: comites, literally "companion (for military affairs)", the origin of the medieval noble rank of count), irrespective of where the emperor(s) were.^[89] These regional armies became steadily more numerous until, by the time of the Notitia, there were three in the East and six in the West.^[90] Their evolution was a partial reversal of Constantine's policy and, in effect, a vindication of Zosimus' critique that the limitanei forces had been left with insufficient support.^[91] But the imperial escort armies remained in existence, and in ca. 420 the three comitatus praesentales listed in the Notitia, each 20–30,000 strong, still contained a total of ca. 75,000 men.^[92] If one accepts that the army at the time numbered about 350,000 men, the escort armies still contained 20–25% of the total effectives.

Regiments which remained with the escort armies were, not later than 365, denoted palatini (lit. "of the palace", from palatium), a higher grade of comitatenses.^[93] Regiments were now classified in four grades, which denoted quality, prestige and probably pay. These were, in descending order, scholares, palatini, comitatenses and limitanei.^[94]

Army size

The traditional view of scholars is that the 4th century army was much larger than the 2nd century army, in the region of double the size. The late 6th century writer Agathias, gives a global total of 645,000 effectives for the army "in the old days", presumed to mean at its peak under Constantine I.^[95] This figure probably includes fleets, giving a total of ca. 600,000 for the army alone. A.H.M. Jones' Later Roman Empire (1964), which contains the fundamental study of the late Roman army, calculated a similar total of 600,000 (exc. fleets) by applying his own estimates of unit strength to the units listed in the Notitia Dignitatum.^[96]

But the Agathias-Jones view has fallen out of favour with some historians in more recent times. Agathias' figure, if it has any validity at all, probably represents the official, as opposed to actual strength of the Constantinian army. In reality, the slim evidence is that late units were often severely under-strength, perhaps only about two-thirds of official.^[97] Thus Agathias' 600,000 on paper may not have been more than ca. 400,000 in reality. The latter figure accords well with the other global figure from ancient sources, that of the 6th century writer John Lydus of 389,704 (excluding fleets) for the army of Diocletian. Lydus' figure is accorded greater credibility than Agathias' by scholars because of its precision (implying that it was found in an official document) and the fact that it is ascribed to a specific time period.^[98]

Jones' figure of 600,000 is based on assumptions about unit strengths which may be too high. This especially concerns limitanei units (there is less dispute about the size of comitatus units, for which there is more available evidence). Jones calculated unit strengths in Egypt under Diocletian using papyrus evidence of unit payrolls. But a rigorous reassessment of the evidence by R. Duncan-Jones concluded that Jones had overestimated unit sizes by 2–6 times.^[99] For example, Jones estimated legions on the frontiers at ca. 3,000 men.^[100] But Duncan-Jones' revisions found frontier legions of around 500 men, an ala of just 160 and an equites unit of 80. Even allowing for the possibility that some of these units were simply detachments from larger units, it is likely that Diocletianic unit strengths were far lower than earlier.^[101]

Duncan-Jones' figures receive support from a substantial corpus of excavation evidence from all the imperial borders which suggests that late forts were designed to accomodate much smaller garrisons than their Principate predecessors. Where such sites can be identified with forts listed in the Notitia, the implication is that the resident units were also smaller. Examples include the Legio II Herculia, created by Diocletian, which occupied a fort just one-seventh the size of a typical Principate legionary base, implying a strength of ca. 750 men. At Abusina on the Rhine, the Cohors III Brittonum was housed in a fort only 10% the size of its old Trajanic fort, suggesting that it numbered only around 50 men. The evidence must be treated with caution as identification with Notitia sites is often tentative and again, the units in question may be detachments (the Notitia frequently shows the same unit in two or three different locations simultaneously). Nevertheless, the weight of the evidence favours small sizes for frontier units.^[102]

At the same time, more recent work has suggested that the regular army of the 2nd century was considerably larger than the ca. 300,000 traditionally assumed. This is because the 2nd century auxilia were not just equal in numbers to the legions as in the early 1st century, but some 50% larger.^[103] The Principate army probably reached a peak of nearly 450,000 (excluding fleets and foederati) at the end of the 2nd century.^[104] Furthermore, the evidence is that the actual strength of 2nd century units was typically much closer to official (ca. 85%).^[105] In any case, estimates of army strength for the Principate are based on much firmer evidence than those for the later period, which are highly speculative, as the table below shows.

NOTE: Regular land army only (excludes irregular barbarian foederati units and Roman navy effectives)

Army structure

The later 4th century army contained three types of army group: (a) imperial escort armies (comitatus praesentales). These were ordinarily based near the imperial capitals (Milan in the West, Constantinople in the East), but usually accompanied the emperors on campaign. (b) Regional field armies (comitatus). These were based in strategic regions, on or near the frontiers. (c) Border armies (exercitus limitanei).^[121]

Types (a) and (b) are both frequently defined as "mobile field armies". This is because, unlike the limitanei units, they were not based in fixed locations. But their strategic role was quite different. The escort armies' primary role was probably to provide the emperor's ultimate insurance against usurpers: the very existence of such a powerful force would deter many potential rivals, and if it did not, the escort army alone was often sufficient to defeat them.^[122] Their secondary role was to accompany the emperor on major campaigns such as a foreign war or to repel a large barbarian invasion.^[123] The regional comitatus, on the other hand, had the task of supporting the limitanei in operations in the region they were based in.^[124]

Command structure

High command structure of the East Roman army ca. 395. Based on the Notitia Dignitatum. Troop numbers based on recent unit size estimates. Reporting structure as in Jones (1964) 100 and 609

High command structure of the West Roman army ca. 410–425. Based on the Notitia Dignitatum. Troop numbers based on recent unit size estimates.[125]

The command structures of the Eastern and Western armies of the empire, as recorded in the Notitia Dignitatum, are represented diagramatically in the organisation charts (right). The eastern section of the Notitia is dated to ca. 395, at the death of Theodosius I. The western section was completed later, in the 420's, after the West had been overrun by barbarian tribes.^[126] The Notitia thus describes the evolved structure of the late army after a century of mutation. The position under Diocletian and even Constantine would have been very different.

The three comitatus praesentales (two in the East and one in the West) were each commanded by a magister militum ("master of soldiers", the highest military rank. In the East, this title had by 395 replaced magister peditum and magister equitum as these were no longer related to infantry or cavalry, but they were retained in the West). Each magister reported direct to the emperor and was assisted, at least from the early 5th century, by a deputy called a vicarius. The Eastern structure remained essentially intact until the 6th century.^[127] The Western structure was already in a state of collapse at the time of the Western Notitia.

In the East, the commanders of the five regional comitatus (all of magister rank except the comites of Egypt and Isauria) also reported to the emperor direct, according to the Notitia (although 5th century laws imply that the two comites were subordinate to the magister militum per Orientem). In contrast, the commanders of the western regional comitatus were, unlike their Eastern colleagues, all of the lower comes rank, save for the magister equitum per Gallias: this is because all but the latter comitatus were smaller than the typical 20-30,000 commanded by a magister. They reported to the magister peditum in control of the single Western escort army and the effective supreme commander of the Western army. This anomalous structure had arisen through the ascendancy of the half–barbarian military strongman Stilicho (395-410), who was appointed by Theodosius I as guardian of his infant son and successor Honorius. Unlike in the East, however, Stilicho's successors (e.g. Ricimer) had succeeded in retaining their supreme command. It appears that in the earlier 4th century, both the magister peditum praesentalis and the magister equitum per Gallias reported to the emperor but whether the comites also did so is uncertain.^[128]

Under the command of the regional magistri and comites were the duces in command of border forces in their sector. This was the case from at least the 360's onwards when the regional comitatus became permanent. Before that, the duces may have reported to the magistri of the imperial escort armies. In the time of Diocletian, the duces reported to the vicarius of their diocese.^[129]

Outside the normal military chain of command were the scholae, the emperors' personal cavalry escort. They did not belong to the comitatus praesentales and reported to the magister officiorum, a civilian official.^[130] However, this was probably only for administrative purposes. On campaign, the tribuni (regimental commanders) of the scholae probably reported direct to the emperor himself.^[131] At the time of the Notitia, each emperor, Eastern and Western, had his own corps of scholae.

Bases

Comitatus troops and border troops had different accommodation arrangements. Most border units were based in forts as were their predecessors, the auxiliary regiments of the Principate (indeed, in many cases, the same forts).^[132] Some of the larger limitanei units (legiones and vexillationes) were based in cities, probably in permanent barracks.^[133]

Comitatus troops were also based in cities (when not on campaign: then they would be in temporary camps). But it seems that did not usually occupy purpose-built accommodation like the city-based limitanei. From the legal evidence, it seems they were normally compulsorily billeted in private houses (hospitalitas).^[134] This is because they often wintered in different provinces. The comitatus praesentales accompanied their respective emperors on campaign, while even the regional comitatus would change their winter quarters according to operational requirements. However, in the 5th century, emperors rarely campaigned in person, so the praesentales became more static in their winter bases.^[135] The Western comitatus praesentalis normally was based in and around Mediolanum (Milan) and the two Eastern comitatus in the vicinity of Constantinople.^[136]

Regiments

The changes to unit structure in the 4th century were reduction of unit sizes and increase in unit numbers, establishment of new unit types and establishment of a hierarchy of units more complex than the old one of legions and auxilia.^[137]

Unit sizes

The evidence for the strength of late army units is very fragmented and equivocal.^[138] The table below gives some recent estimates of unit strength, by unit type and grade:

• Scholae were not technically comitatenses

Much uncertainty remains, especially regarding the size of limitanei regiments, as can be seen by the wide ranges of the size estimates. It is also possible, if not likely, that unit strengths changed over the course of the 4th century. For example, it appears that Valentinian I split about 150 comitatus units with his brother and co-emperor Valens. The resulting units may have been just half the strength of the parent units (unless a major recruitment drive was held to bring them all up to original strength).^[138]

Scholae are believed to have numbered ca. 500 on the basis of a 6th century reference.^[140]

In the comitatus, there is consensus that vexillationes were ca. 500 and legiones ca. 1,000 strong. The greatest uncertainty concerns the size of the crack auxilia palatina infantry regiments, originally formed by Constantine. The evidence is contradictory, suggesting that these units could have been either ca. 500 or ca. 1,000 strong, or somewhere in between.^[141][142] If the higher figure were true, then there would be little to distinguish auxilia from legiones, which is the strongest argument in favour of ca. 500.

For the size of limitanei units, opinion is divided. Jones and Elton suggest from the scarce and ambiguous literary evidence that border legiones numbered ca. 1,000 men and that the other units contained in the region of 500 men each.^[143][144] Others draw on papyrus and more recent archaeological evidence to argue that limitanei units probably averaged about half the Jones/Elton strength i.e. ca. 500 for legiones and around 250 for other units.^[145][146]

Unit types

Scholae

Shield insignia of regiments under the command of the Magister Militum Praesentalis II of the East Roman army ca. 395. Page from the Notitia Dignitatum, a medieval copy of a Late Roman register of military commands

Reenactor wearing the typical equipment of a 3rd century foot soldier. The helmet is a Niederbieber type, with cross-pattern reinforcing ridges on the top of the bowl, and cheek-guards which can be fastened together. The sword is a spatha (median blade length 900 mm), used by the cavalry only in the 1st/2nd c. This soldier carries a spiculum , a heavy pilum-type javelin. Note the chain mail (lorica hamata) shirt and oval shield. Clothing consisted of a long-sleeved tunic, trousers and boots. The equipment of a 4th century infantryman was very similar to the 3rd c., save that the spiculum was usually replaced by a heavy thrusting-spear (hasta) and the helmet was predominantly of the "Intercisa type"^[147]

The scholae consisted, at the end of the 4th century, of five regiments (2,500 men) under the Western Augustus and seven (3,500) in the East. This compares with 2,000 equites singulares in the late 2nd century.^[148] 40 select troops from the scholae, called candidati from their white uniforms, acted as the emperor's personal bodyguards.^[149] All of the Western, and five of the Eastern, scholae were termed schola scutariorum; these were units of 'conventional' heavy cavalry, armoured in a manner similar to the alae of the Principate. The Eastern scholae included two specialised units: the schola scutariorum clibanariorum (first mentioned in 330 in legislation of Constantine I), of very heavily armoured cataphract cavalry, and the schola scutariorum sagittariorum, a unit of horse-archers.^[150]

Comitatenses (inc. palatini)

In the comitatus armies (both escort and regional) cavalry regiments were known as vexillationes, infantry regiments as either legiones or auxilia.^[151] Auxilia were only graded as palatini, emphasising their elite status, while the other two are graded either palatini or comitatenses.^[152]

The majority of Roman cavalry regiments in the comitatus (61%) remained of the traditional semi-armoured type, similar in equipment and tactical role to the alae of the Principate and suitable for mêlée combat. These regiments carry a variety of titles: comites, equites scutarii, equites stablesiani or equites promoti. These titles are probably purely honorary, and do not indicate different unit types or functions.^[153] 24% of regiments were unarmoured light cavalry, denoted equites Dalmatae, Mauri or sagittarii (mounted archers), suitable for harassment and pursuit. Mauri light horse had served Rome as auxiliaries since the Second Punic War 500 years before. Equites Dalmatae, on the other hand, seem to have been regiments first raised in the 3rd century. 15% of comitatus cavalry regiments were heavily armoured cataphracti or clibanarii, which were suitable for the shock charge (all but one such squadrons are listed as comitatus regiments by the Notitia)^[154]

Infantry regiments mostly fought in close order as did their Principate forbears. Infantry equipment was broadly similar to the that of auxiliaries in the 2nd century, with some modifications (see Equipment, below).^[155]

Limitanei

In the limitanei forces, most types of regiment were present. For infantry, there are regiments called milites, numeri and auxilia as well as old-style legiones and cohortes. Cavalry regiments are called equites, cunei and old-style alae.^[156]

The evidence is that comitatenses regiments were considered of higher quality than limitanei. But the difference should not be exaggerated. Suggestions have been made that the limitanei were a part-time militia of local farmers, of poor combat capability. ^[157] This view is rejected by many modern scholars.^{[158][159][160]} In reality, limitanei were full-time professionals.^[161] They were charged with combating the incessant small-scale barbarian raids that were the empire's enduring security problem.^[162] It is therefore likely that their combat readiness and experience were high. This was demonstrated at the siege of Amida (359) where the besieged frontier legions resisted the Persians with great skill and tenacity.^[163] Elton suggests that the lack of mention in the sources of barbarian incursions less than 400-strong implies that such were routinely dealt with by the border forces without the need of assistance from the comitatus.^[164] Limitanei regiments often joined the comitatus for specific campaigns, sometimes remaining long-term with the title of pseudocomitatenses, implying adequate combat capability.^[165]

Specialists

The late Roman army contained a significant number of heavily armoured cavalry called cataphracti (from the Greek kataphraktos, meaning "covered all over"). These were covered from neck to foot by scale and/or lamellar, and their horses were often armoured also. Cataphracts carried a long, heavy lance called a contus, ca. 3.65 m long, that was held in both hands. Some also carried bows.^[166] The central tactic of cataphracts was the shock charge, which aimed to break the enemy line by concentrating overwhelming force on a defined section of it. A type of cataphract called a clibanarius also appears in the 4th century record. This term may de derived from Greek klibanos (a bread oven) or from a Persian word. It is likely that clibanarius is simply an alternative term to cataphract, or it may have been a special type of cataphract.^[167] This type of cavalry had been developed by the Iranic horse-based nomadic tribes of the Eurasian steppes from the 6th-century BCE onwards: the Scythians and their kinsmen the Sarmatians. The type was adopted by the Parthians in the 1st century BCE and later by the Romans, who needed it to counter Parthians in the East and the Sarmatians along the Danube.^[168] The first regiment of Roman cataphracts to appear in the archaeological record is the ala I Gallorum et Pannoniorum cataphractaria, attested in Pannonia in the early 2nd century.^[169] Although Roman cataphracts were not new, they were far more numerous in the late army, with most regiments stationed in the East.^[170]

Archer units are denoted in the Notitia by the term equites sagittarii (mounted archers) and sagittarii (foot archers, from sagitta = "arrow"). As in the Principate, it is likely that many non-sagittarii regiments also contained some archers. Mounted archers appear to have been exclusively in light cavalry units.^[171] Archer units, both foot and mounted, were present in the comitatus.^[172] In the border forces, only mounted archers are listed in the Notitia, which may indicate that many limitanei infantry regiments contained their own archers.^[173]

A distinctive feature of the late army is the appearance of independent units of artillery, which during the Principate appears to have been integral to the legions. Called ballistarii (from ballista = "catapult"), seven such units are listed in the Notitia, all but one belonging to the comitatus. But a number are denoted pseudocomitatenses, implying that they originally belonged to the border forces. The purpose of independent artillery units was presumably to permit heavy concentration of firepower, especially useful for sieges. However it is likely that many ordinary regiments continued to possess integral artillery, especially in the border forces.^[174]

The Notitia lists a few units of presumably light infantry with names denoting specialist function: superventores ("interceptors"), exculcatores ("trackers"), exploratores ("scouts"). At the same time, Ammianus describes light-armed troops with various terms: velites, leves armaturae, exculcatores, expediti. It is unclear from the context whether any of these were independent units, specialist sub-units, or indeed just detachments of ordinary troops specially armed for a particular operation.^[175] The Notitia evidence implies that, at least in some cases, Ammianus could be referring to independent units.

Foederati

Outside the regular army were substantial numbers of allied forces, generally known as foederati (from foedus = "treaty") or symmachi in the East. The latter were forces supplied either by barbarian chiefs under their treaty of alliance with Rome or dediticii.^[176] Such forces were employed by the Romans throughout imperial history e.g. the battle scenes from Trajan's Column in Rome show that foederati troops played an important part in the Dacian Wars (101–6).^[177]

In the 4th century, these forces were organised into ill-defined units based on a single ethnic group called numeri ("troops", although numerus was also the name of a regular infantry unit).^[178] They served alongside the regular army for the duration of particular campaigns or for a specified period. Normally their service would be limited to the region where the tribe lived, but sometimes could be deployed elsewhere.^[179]They were commanded by their own leaders. It is unclear whether they used their own weapons and armour or the standard equipment of the Roman army. The more useful and long-serving numeri appear to have been absorbed into the regular late army, rapidly becoming indistinguishable from other units.^[180]

Recruitment

Romans

During the Principate, it appears that most recruits, both legionary and auxiliary, were volunteers (voluntarii). Compulsory conscription (dilectus) was never wholly abandoned, but was generally only used in emergencies or before major campaigns when large numbers of additional troops were required.^[181] In marked contrast, the late army relied mainly on compulsion for its recruitment of Roman citizens. Firstly, the sons of serving soldiers or veterans were required by law to enlist. Secondly, a regular annual levy was held based on the indictio (land tax assessment). Depending on the amount of land tax due on his estates, a landowner (or group of landowners) would be required to provide a commensurate number of recruits to the army.^[182] Naturally, landowners had a strong incentive to keep their best young men to work on their estates, sending the less fit or reliable for military service. There is also evidence that they tried to cheat the draft by offering the sons of soldiers (who were liable to serve anyway) and vagrants (vagi) to fulfil their quota.^[183]

However, conscription was not in practice universal. Firstly, a land-based levy meant recruits were exclusively the sons of peasants, as opposed to townspeople.^[183] Thus some 20% of the empire's population was excluded.^[184] In addition, as during the Principate, slaves were not admissible. Nor were freedmen and persons in certain occupations such as bakers and innkeepers. In addition, provincial officials and curiales (city council members) could not enlist. These rules were relaxed only in emergencies, as during the military crisis of 405–6 (Radagaisus' invasion of Italy and the great barbarian invasion of Gaul).^[185] Most importantly, the conscription requirement was often commuted into a cash levy, at a fixed rate per recruit due. This was done for certain provinces, in certain years, although the specific details are largely unknown. It appears from the very slim available evidence that conscription was not applied evenly across provinces but concentrated heavily in the army's traditional recruiting areas of Gaul (including the two Germaniae provinces along the Rhine) and the Danubian provinces, with other regions presumably often commuted. An analysis of the known origins of comitatenses in the period 350–476 shows that in the Western army, the Illyricum and Gaul dioceses together provided 52% of total recruits. Overall the Danubian regions provided nearly half of the whole army's recruits, despite containing only three of the 12 dioceses.^[186] This picture is much in line with the 2nd century position.^[187]

Prospective recruits had to undergo an examination. Recruits had to be 20–25 years of age, a range that was extended to 19–35 in the later 4th century. Recruits had to be physically fit and meet the traditional minimum height requirement of 6 Roman feet (5ft 10in, 175cm) until 367, when it was reduced to 5 Roman feet and 3 Roman palms (5ft 7in, 167cm).^[188]

Once a recruit was accepted, he was branded to facilitate recognition if he attempted to desert. The recruit was then issued with an identification disk (which was worn around the neck) and a certificate of enlistment (probatoria). He was then assigned to a unit. A law of 375 required those with superior fitness to be assigned to the comitatenses.^[189] In the 4th century, the minimum length of service was 20 years (24 years in some limitanei units).^[190] This compares with 25 years in both legions and auxilia during the Principate.

The widespread use of conscription, the compulsory recruitment of soldiers' sons, the relaxation of age and height requirements and the branding of recruits all add up to a picture of an army that had severe difficulties in finding, and retaining, sufficient recruits.^[191] Recruitment difficulties are confirmed in the legal code evidence: there are measures to deal with cases of self-mutilation to avoid military service (such as cutting off a thumb), including an extreme decree of 386 requiring such persons to be burnt alive.^[190] Desertion was clearly a serious problem, and was probably much worse than in the Principate army, since the latter was mainly a volunteer army. This is supported by the fact that the granting of leave of absence (commeatus) was more strictly regulated. While in the 2nd century, a soldier's leave was granted at the discretion of his regimental commander, in the 4th century, leave could only be granted by a far senior corps commander (dux, comes or magister militum).^[192][193] In addition, it appears that comitatus units were typically one-third understrength.^[194] The massive disparity between official and actual strength is powerful evidence of recruitment problems. Against this, Elton argues that the late army did not have serious recruitment problems, on the basis of the large numbers of exemptions from concription granted.^[195]

Barbarians

Barbari ("barbarians") was the generic term used by the Romans to denote peoples resident beyond the borders of the empire, and best translates as "foreigners" (it is derived from a Greek word meaning "to babble": a reference to their outlandish tongues).

Most scholars believe that significant numbers of barbari were recruited throughout the Principate by the auxilia (the legions were closed to non-citizens).^[196][190] However, there is little evidence of this before the 3rd century. The scant evidence suggests that the vast majority, if not all, of auxilia were Roman peregrini (second-class citizens) or Roman citizens.^[197] In any case, the 4th century army was probably much more dependent on barbarian recruitment than its 1st/2nd century predecessor. The evidence for this may be summarised as