Structural history of the Roman military

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This article is part of the series on: Military of ancient Rome (Portal) 800 BC - AD 476

Structural history

Roman army (unit types and ranks, legions, generals)

Roman navy (fleets, admirals)

Campaign history

Lists of Wars and Battles

Decorations and Punishments

Technological history

Military engineering (castra, siege engines, arches, roads)

Personal equipment

Political history

Strategy and tactics

Infantry tactics

Frontiers and fortifications (Limes, Hadrian's Wall)

The structural history of the Roman military describes the changes in constitution and organisation of the military forces of ancient Rome, from around 800 BC to around 476 AD. The highest level branches of the military of ancient Rome were the Roman army and the Roman navy. Within these top-level branches the actual structure of the Roman military was subject to substantial change throughout the history of ancient Rome. The general trend in Rome's military can however be generalised as three phases. In the first phase, Rome's military consisted of citizen soldiers performing military service as part of their duty to the state, making seasonal campaigns against largely local adversaries.

As the territories belonging to Rome increased, along with the size of its army, the soldiery of ancient Rome was increasingly professional and salaried, with military service at the lower (non-staff) levels becoming longer-term. Military units were, largely, homogeneous, and well defined and regulated. The basic army unit consisted of legions of infantry as well as non-legionary allied troops known as auxilia, often providing cavalry support.

In the final phase of Rome's military, military service continued to be salaried and professional, but the trends of employing allied or mercenary troops was expanded such that they became the majority of Rome's forces. At the same time, the uniformity of structure found in Rome's earlier military forces disappeared, and soldiery ranged from lightly-armed mounted archers to heavy infantry. This was accompanied by a general trend of increasing reliance on cavalry.

Contents 1 Tribal forces (800 BC - 578 BC) 2 Etruscan-model hoplites (578 BC - 510 BC) 3 Manipular legion (509 BC - 217 BC) 4 Proletariatisation of the infantry (217 BC to 107 BC ) 5 Marian legion (107 BC - 49 BC) 6 Non-Citizen Recruitment (49 BC - 27 BC) 7 Imperial legions and reformation of the auxilia (27 BC - 75 AD) 8 Introduction of vexillationes (76 AD - 117 AD) 9 Barbarisation of the army (117 AD - 253 AD) 10 Rise of the cavalry (254 AD - 306 AD) 11 Comitatenses and limitanei (307 AD - 358 AD) 12 Barbarian Allies (358 AD - 476 AD) 13 Collapse in the West and Survival in the East (395 AD - 476 AD) 14 References 14.1 Citations 14.2 Bibliography

[edit] Tribal forces (800 BC - 578 BC)

The early Roman army is often referred to as Rome's curiate army, named for the subdivisions of the three founding tribes (Latin: curia) of Rome. It was a relatively small force and consisted "mainly of raiding and cattle rustling with the occasional skirmish-like battle".^[1] It lacked much of the professionalism and organisation of later armies, with individual units or regiments being probably established on a tribal or gens-based basis. Although the army would have had an infantry element since its inception sometime in the first millennia BC, the cavalry, known as the celeres or literally "the swift", was, according to tradition, only formed in the time of the apocryphal Romulus.^[2] During this period Rome was probably fortified as a hill-top village and its army can be compared loosely to a typical Iron-Age warrior band led by a warrior chieftain. Much of the arms and armour of this period was very similar to the rest of Villanovan culture, with swords being fashioned of bronze. Patterns were very similar to the bronze antennae hilted weapons in use by other peoples of the age.

The army (Latin: legio) according to Livy consisted of exactly 3,000 infantry and 300 cavalry during this period, one third from each tribe.^[3] The numbers are a little too exact and Livy's historical remove too great for these figures to be taken too literally, but Livy is correct that the greater mass of the army at this time would have consisted of footsoldiers (Latin: pedites), probably undifferentiated infantry armed with javelins. The cavalry (Latin: celeres) would have been small in number and probably consisted of the richest citizens.

By the 7th century BC, Etruscan civilization was dominant in the region. As with most of the other peoples in the region, the Romans warred against the Etruscans and by the close of the 7th century the Etruscans had conquered Rome and established a military dictatorship or kingdom.

[edit] Etruscan-model hoplites (578 BC - 510 BC)

Although several Roman sources talk extensively about the Roman army of the Roman Kingdom, including Livy and Polybius, none of them are contemporary sources - Polybius, for example, was writing some 300 years after the events in question, and Livy some 500 years later. The sources can therefore not be seen as reliable as on later military history from the First Punic War onwards.

The three Etruscan kings of Rome, according to tradition, are Tarquinius Priscus, Servius Tullius, and Tarquinius Superbus. The reformation of the army during this period into the centurial army based on socio-economic class^[4] is traditionally attributed to the second of these Etruscan kings (and the sixth apocryphal king), Servius Tullius. Livy tells us that Tullius reformed the army as a result of his transplanting onto the army the structure derived for civil life from his conducting the first Roman census. At all levels the military was considered to be a civic responsibility at this time and a way of advancing one's status within Roman society.^[5]

However, since Rome's social classes were qualified rather than created by the census - and given that Tullius was not the first Etruscan king of Rome but the second - it is perhaps more accurate to say that the army's structure was more closely defined during this period rather than reformed: the qualification of "First Class" citizens (those who qualified to serve militarily as heavy armoured infantry) as being those with 100,000 or more asses (Latin: as (coin)) in assets doesn't alter the fact that even prior to such classification, poorer citizens would not have been able to afford the arms and armour to serve as heavy infantry in any case.

The army is traditionally said to have doubled in size at this point from 3,000 to 6,000 men, consisting of 60 centuries of 100 men each.^[6] The army consisted of a number of troop types based upon the social class of qualified citizens, collectively known as adsidui. From the poorest in the "fifth class" to the richest in the "first class" and the equestrians above them, military service was compulsory for all.^[7] However, on the contrary to being seen as a burden, military service was, in contrary to later Roman views, at this time seen as a proper undertaking of duty. Whereas there are accounts of Romans in the late empire mutilating their own bodies to exempt them from military service, there seems to have been no such reluctance to serve in the military of early Rome.

The equestrians, the highest social class of all, served as the mounted cavalry units of the equites. The first class of the richest citizens served as heavy infantry with swords and long spears (resembling hoplites), and provided the first line of the battle formation. The second class were armed similarly to the first class, but without a breastplate and with an oblong rather than a round shield, and stood behind the first class in battle formation. The third and fourth classes were more lightly armed with a thrusting spear and throwing javelins, and stood behind the second class in battle formation, providing javelin support. The poorest men of the fifth class were generally too poor to afford much equipment at all and were armed as skirmishers with slings and stones; they would be deployed in a screen in front of the main army, covering its approach and masking its manoeuvers.

The very poorest of men, those excluded from the qualifying social classes of the adsidui, were exempted from military service on the grounds that they were too poor to provide themselves with any arms whatsoever.^[7] However, in the most pressing circumstances, even these proletarii would have been pressed into service,^[8] though their military worth was probably questionable.

[edit] Manipular legion (509 BC - 217 BC)

It was traditionally supposed that the army of the early Roman republic was created through the military Camillian Reforms of the semi-apocryphal figure of Marcus Furius Camillus, but Grant and others argue that the early republican army was rather created by natural evolution of the pre-existing centurial army, rather than through a singular and deliberate policy of reform.^[9]

At this period an army formation of around 5000 men was known as a legion (Latin: legio). However, contrary to later legions of exclusively heavy infantry, the legions of the Republic consisted of mixed light and heavy infantry and therefore the term manipular army (an army based on units called maniples) is normally used to contrast to the later legionary army of the empire that was based around a system of cohort units. The manipular army of the Roman Republic was based partially upon social class and partially upon age and military experience. It therefore represents theoretically a "halfway house" between the earlier socially-divided army, and the later class-free armies of later years. In practice, as a matter of practicality, even slaves were at one time pressed into the army of the Republic.^[10]

The manipular army gets its name from the tactical deployment of its heavy infantry into maniples, units of 120 men each from a single infantry class. The maniples permitted tactical movement of individual units of infantry on the battlefield within the framework of the greater army. This stratification was further assisted by the typical deployment of the maniples into three discreet lines (Latin: triplex acies) based on the three heavy infantry types of hastati, principes and triarii.^[11] The first line, the hastati, were leather armoured infantry soldiers with an iron-clad wooden shield, 4 feet tall and a convex rectangle in shape, a sword known as a gladius, a brass helmet adorned with 3 feathers approximately 30cm in height, a brass cuirass, and two throwing spears known as pila: one the heavy pilum of popular imagination and one a slender javelin.^[12]

The second line, the principes, were heavy infantry soldiers armed and armoured as per hastati, except wearing a coat of mail.^[12] The triarii formed the third rank and were the last remnant of hoplite-style troops in the Roman army: they were armed and armoured as per the principes, except carrying a pike rather than the two pila.^[12] A manipular legion would typically contain 1200 hastati, 1200 principes and 600 triarii.^[13]

The heavy infantry of the maniples were supported by a number of light infantry (Latin: velites) and cavalry (Latin: equites) troops, typically 300 horsemen per manipular legion.^[11] The cavalry was drawn primarily from the richest class of equestrians but additional cavalry (and light infantry) were drawn at times from the Socii and Latini of the Italian mainland. The equites cavalry was still drawn from the equestrian class of nobles in Roman society, and the remaining classes may have retained some slight parallel to social divisions within Roman society, but in theory at least the three lines were based upon: young, unproven men as hastati; older men with some military experience as principes; and veteran troops of advanced age and experience as triarii.

There was an additional class of troop (Latin: accensi), (also adscripticii and later supernumerarii), who followed the army without specific martial roles and would be deployed to the rear of the triarii. They were taken both to supply any vacancies that might occur in the maniples but also seem to have acted sometimes as orderlies to the officers.

The light infantry of 1200 velites^[11] consisted of unarmoured skirmishing troops drawn from the youngest and lower social classes. They were armed with a sword and buckler (3 foot diameter), as well as several light javelins, each with a 3 foot wooden shaft the diameter of a finger, with a 20-30cm narrow metal point.^[12] Their numbers would be swollen by the addition of allied light infantry and irregular rorarii.

A small navy had operated at a fairly low level from the Second Samnite War onwards but it was massively upgraded during this period, expanding from a few primarily river- and coastal-based patrol craft to a full maritime unit of more than 400 ships on the Carthaginian pattern and 100,000 sailors and embarked troops for battle. It thereafter declined in size, partially since a pacified Roman Mediterranean called for little naval force and partially because the Romans chose to rely for some time on ships provided by Greek cities with greater maritime experience.^[14]

[edit] Proletariatisation of the infantry (217 BC to 107 BC )

The extraordinary demands of the Punic Wars meant that a certain flexibility of the existing Camillian military arrangements were required due to a shortage of manpower.^[15] In 217 BC, Rome was forced to effectively ignore wealth considerations for army service when they pressed slaves into naval service^[10] and around 213 BC the official property requirement was reduced from 11,000 to 4,000 asses.^[10] Since it seems improbable that the Romans resorted to employing slaves in their armies in favour of poor citizens,^[16] it must be assumed that in reality at this point the proletarii of the poorest citizens must have been pressed into service despite their legal lack of qualification for military service. By 123 BC, the financial requirement for military service was slashed again from 4,000 asses to just 1,500 asses.^[17] In practice, then, many of the former proletarii had by this time been admitted into the adsidui.^[17]

During the second century, Roman territory saw an overall decline in population,^[18] partially due to the huge losses incurred during various wars. This was accompanied by severe social stresses and the greater collapse of the middle classes into lower classes of the census and the proletarii.^[18] As a result, both the Roman society and its military became increasingly proletarianised. The Roman state was forced to arm its soldiers at the expense of the state, since many of the soldiers who made up its lower classes were now impoverished proletarii in all but name and were too poor to afford their own equipment.^[18]

The distinction between the heavy infantry types of hastati, principes and triarii began to blur, perhaps because the state was now assuming the responsibility of providing standard-issue equipment to all but the first class of troops, who were alone able to afford their own equipment.^[18] By the time of Polybius therefore the triarii or their successors still represented a distinct heavy infantry type armed with a unique style of cuirass, but the hastati and principes were indistinguishable.^[18]

In addition, the shortage of available manpower led to a greater burden being placed upon allies for the provision of allied troops known as socii.^[19] Where accepted allies could not provide the required force types, the Romans were not adverse in this period to hiring mercenaries to fight alongside the legions.^[20]

[edit] Marian legion (107 BC - 49 BC)

In a process known as the Marian reforms, Gaius Marius carried out a deliberate reform of the Roman military. In 107 BC Marius opened up eligibility of entry into the Roman army to all citizens, regardless of wealth or social class,^[10] formalising and concluding a gradual process of removing property requirements for military service that had been continuing for centuries.^[21] The distinction between hastati, principes and triarii which had already become blurred was officially removed^[11] and the legionary infantry of popular imagination was created, forming a homogeneous force of heavy infantry. These legionaries were drawn from citizen stock and by this time Roman or Latin citizenship had been regionally expanded over much of ancient Italy and Cisalpine Gaul.^[22] Lighter citizen infantry, such as the velites, and equites were replaced by non-citizen auxilia that could consist of foreign mercenaries. In practice, due to their unbalanced concentration on heavy infantry^[23] the legions depended on their cavalry attachments and were almost always accompanied through tactical necessity by an approximately equal number of lighter auxiliary troops^[24] drawn from the non-citizens of the Empire's territories. However, there is at least one known exception of legions being formed from non-citizen provinces such as Galatia during this period.^[22]

After Marius, the legions were drawn largely from volunteer citizens rather than citizens conscripted for duty.^[25] Volunteers came forward and were accepted by this point not from citizens of the city of Rome itself but from the surrounding countryside and smaller towns.^[26] Some were classed as veterans in that they were long-term professionals, but greater in numbers were civilians with limited experience who would be in active service perhaps only for a few campaigns.^[27] The legions of the late republic remained, unlike the legions of the later empire, predominantly Roman in origin, although some small number of ex-auxiliary troops were probably incorporated.^[28] The army's higher-level officers and commanders were still drawn exclusively from the aristocracy of Rome.^[29]

The legionaries received standard pay by this time and were not fighting simply on a seasonal basis to protect their land, as earlier, but on a salaried and fixed term basis. As a consequence, military duty appealed most to the poorest sections of society^[30] and the army consisted of a far higher proportion of the poor, particularly the rural poor, than it had previously. A destabilising consequence of this development was that the proletariat "acquired a stronger and more elevated position"^[30] within the state. This professionalisation of the military was made necessary by the need to provide permanent garrisons for territories such as Hispania, something not possible under an army consisting of seasonal citizen militia.

However, R E Smith notes that the need to raise legions in an emergency in response to strategic threats may have resulted in two types of legion.^[31] Long-standing legions deployed overseas would be professional troops forming a standing army; quickly-formed new legions would have consisted instead of younger men, perhaps with little or no military experience, hoping for adventure and plunder. ^[31] However, no distinction in basic pay, discipline or armour is known of between the two types of legion and the practice of veteran troops signing up again voluntarily must have meant that no one army conformed exactly to one or other of these theoretical archetypes.

The legion of the late republic was, structurally, almost entirely heavy infantry. Its main sub-unit was called a cohort and consisted of approximately 480 infantrymen.^[32] The cohort was therefore a much larger unit than the earlier, smaller maniple sub-unit. The cohort itself was divided into six tactical sub-units known as centuriae of 80 men^[32] distributed among 10 "tent groups" (Latin: contubernia) of 8 men each. Legions additionally consisted of a small body, typically, 120 men, of Roman legionary cavalry (Latin: equites legionis) used as scouts and dispatch riders rather than battlefield cavalry,^[33] and a dedicated group of artillery crew of perhaps 60 men.^[32]

Each legion was normally partnered by an approximately equal number of non-Roman auxiliae,^[34] a formalisation of the earlier arrangement of using light allied troops from the Socii and Latini who had received Roman citizenship after the Social War.^[35] Auxiliary troops could be formed from either auxiliary light cavalry known as alae, auxiliary light infantry known as cohors auxiliae, or a flexible mixture of the two known as cohors equitata.^[34] Cavalry types included mounted archers (Latin: sagittarii), heavy shock cavalry (Latin: cataphractii or clibanarii), or lancers (Latin: antesignani or lancearii). Infantry could be armed with bows, slings, throwing spears, long swords, or thrusting spears. Auxilia units were originally led by their own chiefs and in this period their internal organization was left to their commanders.^[36]

However, "the most obvious deficiency" of the Roman army remained its shortage of cavalry, especially heavy cavalry.^[37] The majority of even the auxiliary troops were infantry and Luttwak argues that the "classic trio" of auxiliary forces was Cretan archers, Balearic slingers and Numidian infantry. ^[38] As Rome's adversaries changed from largely infantry-based to largely cavalry-based troops, the infantry-based Roman army began to find itself at a tactical disadvantage.

After having declined in size following the subjugation of the Mediterranean, the Roman navy underwent short-term upgrading and revitalisation in the late Republic to meet several new demands placed upon it. Under Caesar an invasion fleet was assembled in the English Channel to allow the invasion of Britannia, and under Pompey a large fleet was raised in the Mediterranean sea as a task force to clear the sea of Cilician pirates.^[14] During the civil war that followed, as many as a thousand ships were either constructed or pressed into service from Greek cities.^[14]

[edit] Non-Citizen Recruitment (49 BC - 27 BC)

By the time of Julius Caesar in 54 BC, the regular legionary units were supplemented by a body of scouts known as exploratores and a group of spies used to infiltrate enemy camps and known as speculatores.^[39]

Due to the demands of the civil war, the extraordinary measure of recruiting legions from non-citizens was taken: by Caesar in Transalpine Gaul, by Brutus in Macedonia and by Pompey in Pharsalus.^[40] This irregular and extraordinary recruitment paved the way for the general adoption of this practice in the early empire.

[edit] Imperial legions and reformation of the auxilia (27 BC - 75 AD)

The primary military concern under Augustus was the prevention of usurpation of the imperial throne by Roman generals.^[41] The experience of Caesar and, earlier, Marius and Sulla, had demonstrated the willingness of "emergency" legions containing troops keen for plunder to follow their generals against the state. Augustus therefore removed the need for such emergency armies by increasing the size of the standing armies to a size sufficient to provide territorial defence on their own.^[41] Perhaps for similar reasons of concern of usurpation, the legions and auxiliaries of the army were supplemented under Augustus by an elite formation of imperial guards based in Rome known as the Praetorian Guard, as well as a similar formation known as the Cohortes urbanae. The legions, which had been a mix of life professionals and civilian campaigners was altered into a standing army of professionals only.^[42] The actual structure of the cohort army remained much the same as in the late Republic, although around the first century AD the first cohort was doubled in size to total 960 soldiers.^[42][43]

However, whilst the structure remained much the same, the make-up of the legions gradually changed. Whereas early Republican legions had been raised by a draft from eligible Roman citizens, imperial legions recruited solely on a voluntary basis and from a much wider base of manpower - whereas Republican legions had been limited to citizens only, and financially qualified citizens at that, early Imperial legions were open to non-citizens from any territory within the conquered empire.^[44] Caesar, for example, had recruited from Cisalpine Gaul, and by the time of Augustus, recruitment from Rome itself and Central Italy had "almost certainly" ceased.^[44]

The trend of increasing foreign recruitment continued with not just the proportion of non-Roman Italians in the legions increasing, but also the proportion of non-Italian provincials. One estimate places the proportion of Italian troops in the legions as sixty five percent under Augustus at the start of the first century AD, falling to around 49 percent by the end of Nero's reign.^[45]

At the same time, the auxilia were reorganized and a number of allied troops formalized into standing units similar to legions - rather than being raised reactively when required, the process of raising them was carried out in advance of conflicts according to annual targets.^[46] Whereas the internal organization of the auxilia had previously been left up to their commanders, in the early empire they were organised into units known as turmae.^[47] Although never becoming as standardised in their equipment as the legions,^[48] the size of the units as a minimum was standardised to some degree. Cavalry would be formed into either an ala quingenaira of 512 horsemen, or an ala millaria of 1000 horsemen.^[34] Likewise, infantry auxilia could be formed into a cohors quingenaria of 500 men or a cohors millaria of 1000 men.^[34] Mixed cavalry/infantry auxiliaries were typically formed with a larger proportion of foot than horse troops: the cohors equitata quingenaria consisted of 380 foot and 120 horsemen, and the cohors equitata millaria consisted of 760 foot and 240 horsemen.^[34]

The vitality of the empire at this point was such that the use of native auxilia in the Roman army did not apparently barbarise it^[49] but, on the contrary, those serving in the auxilia were granted Roman citizenship on retirement and their sons would be eligible for service in the legions.^[50]

As with the army, many non-Italians were recruited into the Roman Navy, partly because the Romans had never readily taken to the sea.^[51] It appears that the navy was considered to be slightly less prestigious than the auxilia^[51] but, like the auxilia, troops could gain citizenship on discharge upon retirement. In terms of structure, each ship was staffed by a group of men approximately equivalent to a century, with ten ships forming a naval squadron.^[51]

[edit] Introduction of vexillationes (76 AD - 117 AD)

By the final years of the first century AD, the proportion of Italians in the legions had fallen to as low as 22 percent by one account.^[45] At the same time, the borders of the empire having reached their greatest extent under the emperor Trajan, the army's role increasingly transferred to the protection of existing frontiers rather than the expansion into foreign territory that had characterised its earlier existence.^[52] As a result, legions became stationed in largely fixed locations, and although entire legions were occasionally transferred into theatres of war, legions largely remained rooted in one of more legionary bases in a province, detaching smaller bodies of troops (Latin: vexillationes) when they were demanded elsewhere.^[53] This policy was to eventually lead to a splitting of the military's land-based forces into mobile and fixed troops in the later empire. In general, the best troops were despatched as vexillationes and the remainder left to guard border defences were of lower quality, perhaps those with injuries or near retirement.^[54]

[edit] Barbarisation of the army (117 AD - 253 AD)

By the time of the emperor Hadrian the proportion of Italians in the legions had fallen to just one percent.^[45] This lowest figure is probably a direct result of the changing needs of military staffing: a system of fixed border defences (Latin: limes) were established around the empire's periphery under Hadrian, consolidating Trajan's territorial gains. These called for troops to be stationed permanently in the provinces, a prospect more attractive to locally-raised than Italian troops.^[55] The majority of the troops in the legions at the start of the third century AD were from relatively-romanized (though non-Italian) Illyria^[56] but with more and more barbarians being permitted to settle inside, and help in the defence of, Rome's borders, greater numbers of barbarous and semi-barbarous peoples were admitted to the army.^[57]

However, whether this regionalisation of the legions was partnered by a drop in the professionalism of the troops is contested: Santosuosso argues that the strict discipline of the days of Marius had lapsed,^[58] but Alfoldi states that the Illyrian troops were both valiant and warlike.^[59] It seems that discipline in the legions did slacken, with soldiers granted permission to live with wives outside of military lodgings and permitted to adopt a more lavish and comfortable lifestyle, in contrast to the harsh regimen of earlier years.^[60] However it is by no means certain that this led to any reduction in the effectiveness of the legions, due to the greater ferocity of the barbarian recruits. The flavour of the Roman military began not to dictate to but be dictated by its local recruits, leading to a perceived "barbarisation" of Rome's military forces beginning in this period.^[61] The barbarisation of the lower ranks was paralleled by a concurrent barbarisation of its command structure, with the Roman senators who had traditionally provided its commanders becoming entirely excluded from the army and by 235 AD the Emperor, the figurehead of the entire military, was himself born outside of Italy to non-Italian parents.^[62]

The gradual inclusion of greater numbers of non-citizen troops into the military was taken a further step by the creation under Hadrian of a new type of force in addition to the legions and auxilia, known as numeri.^[63] Formed in bodies of around 300 irregular troops,^[34] the numeri were drawn from subjugate provinces and peoples of client-states or even from beyond the borders of the empire. They were both less regimented and less Romanised than auxiliary troops, with a "pronounced national character".^[64], including native dress and native war cries.^[65] The introduction of the numeri was a response to the need for cheap troops, who were nevertheless fierce and provided a force balance of light infantry and cavalry.^[66] They were therefore largely less well armed and less well trained than auxilia or legions, ^[67] although more prestigious elite irregular native troops were also utilised.^[68] However, the legions still made up around one half of the Roman army at this point.^[69]

[edit] Rise of the cavalry (254 AD - 306 AD)

By the late empire enemy forces in both the east and west were "sufficiently mobile and sufficiently strong to pierce [the Roman] defensive perimeter on any selected axis of penetration"^[70] and from the third century onwards both Germanic tribes and Persian armies pierced the frontiers of the Roman empire.^[71] In response, the Roman army underwent a series of changes, more organic and evolutionary than the definitive military reforms of the republic and early empire. Roman forces gradually became more mobile, with one cavalryman for every three infantryman, compared to one in forty in the early Empire,^[72] and a stronger emphasis was placed upon ranged combat ability of all types, such as field artillery, hand-held ballistae, archery and darts. Alfoldi argues that, in 258, Gallienus made cavalry the predominant troop type in the Roman army, over the earlier heavy infantry,^[73] including scutarii and legionary cavalry known as promoti, collectively known as equites.^[74] In around 275 AD, the proportion of catafractarii or clibinarii were also increased.^[75] However, according to Warren Treadgold, the proportion of cavalry did not change between the early 3rd and early 4th centuries.^[76]

The exact histiography is confused but as early as around 295 AD, there seem to have been the beginnings of a central field army to supplement the pattern of forces concentrated around the empire's periphery.^[77] Created and expanded from the core troops of the emperor's personal bodyguards, this force by 295 AD seems to have been too large to be accounted for as a simple bodyguard force, but was still too small to be able to campaign independently of legionary or vexillation support.^[78] It would be expanded further in the fourth century under Constantine.

Additionally, barbarians began to settle in Rome's territories around this time, and the troops they were subsised to provide to the Roman army were no longer organised as numeri but rather were the forerunners of the later entire rented native armies known as foederati.^[79] Though they served under Roman officers, the troops of these units were far more barbarised than the numeri and lacked romanisation of either military structure or personal ideology, nor were they eligible for Roman citizenship upon discharge.^[80] These native troops were not permitted to fight in native warbands under their own leaders as would the later foederati, but rather were split into small groups attached to other Roman units.^[81] They existed therefore as a halfway house between numeri, who were encouraged to be romanised, and the later foederati, who raised officers from their own ranks and were almost entirely self-dependent.

[edit] Comitatenses and limitanei (307 AD - 358 AD)

By the start of the 4th century, the empire's forces were no longer based on a distinction between heavy infantry legions and light infantry and cavalry auxilia but on a distinction between fixed border armies consisting largely of light infantry units and more mobile field armies consisting largely of light infantry and mobile cavalry units. Both types of army were at this point raised from non-Italian peoples living within the empire's borders, many of them recently settled from lands beyond the empire.

The distinction between frontier guard troops and mobile forces that had begun with the use of certain troops to permanentently man frontiers such as Hadrian's Wall in Brittania in the first century AD had led by the late Empire to a trifurcation of troop types. At the very borders fortifications were manned by settled and hereditary troops known as limitanei or riparienses that had evolved from earlier legionary and auxiliary infantry,^[82] in the strategic rear lay more mobile elite reserve troops in a field army known as the comitatenses, and somewhere between the two were provincial reserves known as cunei (cavalry) and auxilia (infantry, not be be confused with earlier meaning of the word) that had evolved from earlier auxiliary cavalry. Of the three, the limitanei border guards are generally considered to have been of lower quality, although this is sometimes disputed.^[83] Whilst the limitanei were supposed to deal with policing actions and low-intensity conflicts, the emphasis of more serious fighting would fall upon the provincial troops, and the countering of the largest scale incursions fell upon the comitatenses or mobile field troops.

Although units described as legiones existed as late as the fifth century in both the border and field armies,^[84] in practice the legionary system of the empire's early years had entirely disappeared in all but name by the middle of the third century. Since the term legion continued to be used, it is unclear exactly when the structure and role of the legions changed, but sometime during the third and forth centuries, the legions' role as elite heavy infantry evaporated entirely.^[85] Instead, those "legions" that remained were no longer drawn exclusively (and perhaps hardly at all) from Roman citizens. They were smaller bodies of light infantry at times only one sixth the size of early imperial legions, and they were armed with some combination of spears, bows, slings, darts and a long slashing sword,^[85] reflecting a greater contemporary emphasis on ranged fighting^[86] compared to the heavy close-quarters infantry of their legionary forebears. The auxilia and numeri had also largely disappeared.^[87]

In terms of troop quality, the limitanei consisted largely of peasant-soliders that were "grossly inferior" to the earlier legions,^[88] whereas the provincial and field armies, with an emphasis on greater mobility, consisted of cavalry forces, much of them from allied or federated peoples.

[edit] Barbarian Allies (358 AD - 476 AD)

In 358 AD, Rome extended the practice of subsidising barbarian peoples in return for the provision of troops by the wholescale adoption of the Frankish people into the Empire. In return for being allowed to settle as foederati in northern Gaul on the near side of the Rhine, the Franks were expected to defend the empire's borders in their territory, and to provide troops to Rome.

In 376 certain Goths asked Emperor Valens to allow them to settle on the southern bank of the Danube river on a similar basis to the Franks, and were also accepted into the empire as foederati. Later that year the Goths rose in rebellion and defeated the Romans in the Battle of Adrianople. The serious loss of military manpower ironically forced the Roman Empire to rely still further on such foederati troops to supplement its forces.^[89]

The Roman Army often recruited non-Roman soldiers into regular military units, as well as seperate allied contingents (of laeti and foederatii). Most soldiers were probably still non-Italian Roman citizens, though many were probably non-citizen barbarians.^[90]

[edit] Collapse in the West and Survival in the East (395 AD - 476 AD)

The non-federated mobile field army known as the comitatenses was eventually split into a number of smaller field armies: a strategically central field army known as the comitatense palatina or prasental under the emperor's direct control; and several other regional field armies.^[11] Santosuosso believes that the latter gradually degraded into low-quality garrison units similar to the limitanei that they either supplemented or replaced.

In 395 the Western Roman Empire therefore had several regional field armies in Italy, Illyricum, Gaul, Britannia and Africa and about twelve border armies; by about 430 they had two more field armies in Hispania and Tingitania^[91] but had lost control of Britannia and much of Africa and Gaul. In the same period the Eastern Roman Empire had two Field Armies in the Emperor's Presence (at Constantinople), three regional field armies (in the East, in Thrace, and in Illyricum) and fifteen frontier armies. The eastern armies totalled about 300,000 soldiers and 30,000 seamen.^[92][93]

In 451, Attila the Hun was defeated only with help of the foederati (who included the Visigoths and Alans). By the fifth century many of the empire's borders had been entirely denuded of troops to support the central field army. With barbarian incursions striking as far as the heart of Italy, and Rome's borders collapsing, forces defending frontiers could swiftly find themselves cut off deep in the enemy's rear.^[94] With barbarian warbands penetrating the empire's borders, both as settlers and invaders, Rome's main military strength rested in the rented mercenary barbarian troops known as foederati.^[94]

When these barbarian troops realised, first, that there was nothing standing between them and the empire's riches, and second, that the empire's coin could be gained more profitably by ravaging its territory than by serving it, barbarian troops in Rome's own pay unseated the last emperor of the western Roman Empire.

The eastern Roman military (now the Byzantine army and Byzantine navy) continued to defend the eastern Roman empire (now the Byzantine Empire) until 1453.

[edit] References

[edit] Citations

[edit] Bibliography

Primary sources Livy, The Rise of Rome, Oxford University Press, 1998 Ammianus Marcellinus, Res Gestae a Fine Corneli Taciti, unknown publisher, unknown date Notitia Dignitatum, unknown publisher, unknown date Polybius, History, unknown publisher, unknown date Tacitus, Annals, unknown publisher, unknown date

Secondary and tertiary sources A Alfoldi, The Crisis of the Empire (AD 249-270), in S A Cook et all (eds.), The Cambridge Ancient History, Vol. XII: The Imperial Crisis and Recovery (AD 193-324), pp. 208ff. Brian Campbell, The Army, in The Crisis of Empire, AD 193-337, in The Cambridge Ancient History, Second Edition, Vol. XII Hugh Elton, Warfare in Roman Europe, unknown publisher, 1996 Emilio Gabba, Republican Rome, The Army and The Allies, University of California Press, 1976 Edward Gibbon, The Decline and Fall of the Roman Empire, Penguin, 1985 Adrian Goldsworthy, In the Name of Rome: The Men Who Won the Roman Empire, Weidenfield and Nicholson, 2003 Michael Grant, The History of Rome, Faber and Faber, 1993 Mark Hassall, The Army, in The High Empire, AD 70-192, in The Cambridge Ancient History, Second Edition, Vol. XI Peter Heather, The Fall of the Roman Empire: A New History, MacMillan, 2005 Arnold Hugh Martin Jones, The Later Roman Empire,Johns Hopkins University Press, 1964 Edward Luttwak, The Grand Strategy of the Roman Empire, Johns Hopkins Philip Matyszak, The Enemies of Rome, Thames and Hudson, 2004 Antonio Santosuosso, Soldiers, Emperors and Civilians in the Roman Empire, Westview Press, 2001 R E Smith, Service in the Post-Marian Roman Army, Manchester University Press, 1958 Warren Treadgold, Byzantium and its Army, unknown publisher, 1995 Graham Webster, The Roman Imperial Army, Barnes and Noble Books, unknown year