title: Imperial Roman army

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


title: Imperial Roman army

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


title: Imperial Roman army

text: "Equites cataphractarii", or simply "cataphractarii" for short, were the heavily armoured cavalry of the Roman army. Based on Sarmatian and Parthian models, they were also known as "contarii" and "clibanarii", although it is unclear whether these terms were interchangeable or whether they denoted variations in equipment or role. Their common feature was scalar armour which covered the whole body and conical helmets. Their lances ("contus") were very long and were held in both hands, precluding the use of shields. In some cases, their horses are also depicted as protected by scalar armour, including head-piece. Normally, they were also equipped with long swords. In some cases, they carried bows instead of lances.


title: Imperial Roman army

text: Together with new units of light mounted archers, the "cataphractarii" were designed to counter Parthian (and, in Pannonia, Sarmatian) battle-tactics. Parthian armies consisted largely of cavalry. Their standard tactic was to use light mounted archers to weaken and break up the Roman infantry line, and then to rout it with a charge by the "cataphractarii" concentrated on the weakest point. The only special heavy cavalry units to appear in the 2nd century record are: "ala Ulpia contariorum" and "ala I Gallorum et Pannoniorum cataphractaria" stationed in Pannonia and Moesia Inferior respectively in the 2nd century. Both faced the so-called "Sarmatian salient" between the Roman territories of Pannonia and Dacia, i.e., the Hungarian Plain, the territory of the Iazyges, a Sarmatian tribe which had migrated there and seized control of it during the 1st century.


title: Imperial Roman army

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


title: Imperial Roman army

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


title: Imperial Roman army

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


title: Imperial Roman army

text: A substantial number of auxiliary regiments (32, or about one in twelve in the 2nd century) were denoted "sagittariorum", or archer-units (from "sagittarii" lit. "arrow-men", from "sagitta" = "arrow": It. "saetta", Rom. "sageata"). These 32 units (of which four were double-strength) had a total official strength of 17,600 men. All three types of auxiliary regiment ("ala", "cohors" and "cohors equitata") could be denoted "sagittariorum". Although these units evidently specialised in archery, it is uncertain from the available evidence whether all "sagittariorum" personnel were archers, or simply a higher proportion than in ordinary units. At the same time, ordinary regiments probably also possessed some archers, otherwise their capacity for independent operations would have been unduly constrained. Bas-reliefs appear to show personnel in ordinary units employing bows.


title: Imperial Roman army

text: From about 218 BC onwards, the archers of the Roman army of the mid-Republic were virtually all mercenaries from the island of Crete, which boasted a long specialist tradition. During the late Republic (88–30 BC) and the Augustan period, Crete was gradually eclipsed by men from other, much more populous, regions with strong archery traditions, newly subjugated by the Romans. These included Thrace, Anatolia and above all, Syria. Of the thirty-two "sagittarii" units attested in the mid 2nd century, thirteen have Syrian names, seven Thracian, five from Anatolia, one from Crete and the remaining six of other or uncertain origin.


title: Imperial Roman army

text: Three distinct types of archers are shown on Trajan's Column: (a) with scalar cuirass, conical steel helmet and cloak; (b) without armour, with cloth conical cap and long tunic; or (c) equipped in the same way as general auxiliary foot-soldiers (apart from carrying bows instead of javelins). The first type were probably Syrian or Anatolian units; the third type probably Thracian. The standard bow used by Roman auxilia was the recurved composite bow, a sophisticated, compact and powerful weapon.


title: Imperial Roman army

text: From about 218 BC onwards, the Republican army's slingers were exclusively mercenaries from the Balearic Islands, which had nurtured a strong indigenous tradition of slinging from prehistoric times. As a result, in classical Latin, "Baleares" (literally "inhabitants of the Balearic Islands") became an alternative word for "slingers" ("funditores", from "funda" = "sling": It. "fionda", Fr. "fronde"). Because of this, it is uncertain whether the most of the imperial army's slingers continued to be drawn from the Balearics themselves, or, like archers, derived mainly from other regions.


title: Imperial Roman army

text: Independent slinger units are not attested in the epigraphic record of the Principate. However, slingers are portrayed on Trajan's Column. They are shown unarmoured, wearing a short tunic. They carry a cloth bag, slung in front, to hold their shot ("glandes").


title: Imperial Roman army

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


title: Imperial Roman army

text: Throughout the Principate period, there is evidence of ethnic units of "barbari" outside the normal auxilia organisation fighting alongside Roman troops. To an extent, these units were simply a continuation of the old client-king levies of the late Republic: "ad hoc" bodies of troops supplied by Rome's puppet petty-kings on the imperial borders to assist the Romans in particular campaigns. Some units, however, remained in Roman service for substantial periods after the campaign for which they were raised, keeping their own native leadership, attire and equipment and structure. These units were variously called by the Romans "socii" ("allies"), "symmachiarii" (from "symmachoi", Greek for "allies") or "foederati" ("treaty troops" from "foedus", "treaty"). One estimate puts the number of "foederati" in the time of Trajan at c. 11,000, divided into c. 40 "numeri" (units) of c. 300 men each. The purpose of employing "foederati" units was to use their specialist fighting skills. Many of these would have been troops of Numidian cavalry (see light cavalry above).


title: Imperial Roman army

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


title: Imperial Roman army

text: As all-citizen formations and symbolic protectors of the dominance of the Italian "master-nation", legions enjoyed greater social prestige than the auxilia for much of the Principate. This was reflected in better pay and benefits. In addition, legionaries were equipped with more expensive and protective armour than auxiliaries, notably the "lorica segmentata", or laminated-strip armour. However, in 212, the Emperor Caracalla granted Roman citizenship to nearly all the Empire's freeborn inhabitants. At this point, the distinction between legions and auxilia became moot, the latter becoming all-citizen units also. The change was reflected in the disappearance, during the 3rd century, of legionaries' special equipment, and the progressive break-up of legions into cohort-sized units like the auxilia.


title: Imperial Roman army

text: The military chain of command was relatively flat. In each province, the deployed legions' "legati" (legion commanders, who also controlled the auxiliary units attached to their legion) reported to the "legatus Augusti pro praetore" (provincial governor), who also headed the civil administration. The governor in turn reported directly to the Emperor in Rome. There was no general staff in Rome, but the leading "praefectus praetorio" (commander of the Praetorian Guard) often acted as the Emperor's "de facto" military chief-of-staff.


title: Imperial Roman army

text: Compared to the subsistence-level peasant families from which they mostly originated, legionary rankers enjoyed considerable disposable income, enhanced by periodical cash bonuses on special occasions such as the accession of a new emperor. In addition, on completion of their term of service, they were given a generous discharge bonus equivalent to 13 years' salary. Auxiliaries were paid much less in the early 1st century, but by 100 AD, the differential had virtually disappeared. Similarly, in the earlier period, auxiliaries appear not to have received cash and discharge bonuses, but probably did so from the reign of Hadrian onwards. Junior officers ("principales"), the equivalent of non-commissioned officers in modern armies, could expect to earn up to twice basic pay. Legionary centurions, the equivalent of senior warrant officers, were organised in an elaborate hierarchy. Usually promoted from the ranks, they commanded the legion's tactical sub-units of "centuriae" (about 80 men) and cohorts (about 480 men). They were paid several multiples of basic pay. The most senior centurion, the "primus pilus", was automatically elevated to equestrian rank on completion of his single-year term of office. The senior officers of the army, the "legati legionis" (legion commanders), "tribuni militum" (legion staff officers) and the "praefecti" (commanders of auxiliary regiments) were all of at least equestrian rank. In the 1st and early 2nd centuries, they were mainly Italian aristocrats performing the military component of their "cursus honorum" (conventional career-path). Later, provincial career officers became predominant. Senior officers were paid enormous salaries, multiples of at least 50 times a soldier's basic pay.


title: Imperial Roman army

text: Soldiers spent only a fraction of their lives on campaign. Most of their time was spent on routine military duties such as training, patrolling, and maintenance of equipment. Soldiers also played an important role outside the military sphere. They performed the function of a provincial governor's police force. As a large, disciplined and skilled force of fit men, they played a crucial role in the construction of a province's military and civil infrastructure. In addition to constructing forts and fortified defences such as Hadrian's Wall, they built roads, bridges, ports, public buildings and entire new cities ("colonia"), and cleared forests and drained marshes to expand a province's available arable land.


title: Imperial Roman army

text: Soldiers, mostly drawn from polytheistic societies, enjoyed wide freedom of worship in the polytheistic Roman system. Only a few cults were banned by the Roman authorities, as being incompatible with the official Roman religion or being politically subversive, notably Druidism and Christianity. The later Principate saw the rise in popularity among the military of Eastern mystery cults, generally centred on one deity, and involving secret rituals divulged only to initiates. By far the most popular cult in the army was Mithraism, an apparently syncretist cult which mainly originated in Asia Minor.


title: Imperial Roman army

text: Under the Augustan settlement, the Roman Empire formally remained a republic and ultimate military authority was still vested in the consuls. However actual power resided with the governors – proconsuls or lower promagistrates – who were in charge of all military forces within their province. Hence August moved to secure "supreme proconsular authority" ("imperium proconsulare maius") from the Senate, thereby subjecting the provincial governors to his command and becoming, in effect, commander-in-chief of the Roman army. In addition, the emperor frequently had himself elected as one of the Consuls or Censors. The latter post was especially useful, as it gave him the power to appoint (or remove) members from the roll of Senators and from the Order of Knights, the two aristocratic orders of imperial Rome, which filled all senior administrative and military positions.


title: Imperial Roman army

text: In the border provinces where military units were mostly stationed (i.e. 15-17 of the 42 Hadrianic provinces), the governors mostly bore the title "legatus Augusti pro praetore", although in a few smaller provinces they were known as "procurator" or "praefectus". The governors, who normally held office for three years, commanded all forces in their provinces, both legions and auxilia, as well as being the heads of the civil administration. The governors reported directly to the emperor – there were no intermediate levels of command. However, there are instances during the Principate where the governors of smaller provinces were subordinated to governors of larger neighbouring ones e.g. the "praefectus" (later "procurator") of Judaea was normally subordinate to the "legatus Augusti" of Syria.


title: Imperial Roman army

text: At Rome, there was no army general staff in the modern sense of a permanent central group of senior staff-officers who would receive and analyse military intelligence and advise on strategy. Augustus established a formal "consilium principis" ("imperial council") of magistrates and leading senators in rotation to advise him on all state matters and to prepare draft-decrees for submission to the Senate. But the real decisions were made by a semi-formal group of senior officials and close friends, the "amici principis" ("friends of the emperor"), whose membership was chosen by himself and might vary from time to time. Under Tiberius, the "amici" superseded the formal "consilium" and became the effective governing body of the empire.


title: Imperial Roman army

text: Several "amici" would have had extensive military experience, due to the traditional mixing of civilian and military posts by the Principate aristocracy. But there was no "consilium" specifically dedicated to military affairs. Commanders of the Praetorian Guard, especially if they did not share their command with a partner, might acquire a predominant influence in military decision-making and act as "de facto" military chief-of-staff e.g. Sejanus, who was sole commander of the Guard AD 14–31, most of the emperor Tiberius' rule.


title: Imperial Roman army

text: The emperor and his advisors relied almost entirely on reports from the 17-odd "military" governors for their intelligence on the security situation on the imperial borders. This is because a central military intelligence agency was never established. The imperial government did develop an internal security unit called the "frumentarii". In military jargon, this term, literally meaning "grain-collectors" (from "frumentum" = "grain"), referred to detachments of soldiers detailed to forage food supplies for their units in the field. The term came to be applied to auxiliary soldiers seconded to the staff of the "procurator Augusti", the independent chief financial officer of a province, to assist in the collection of taxes (originally in kind as grain). At some point, probably under Hadrian (r. 117–38), the term acquired a very different meaning. A permanent military unit ("numerus") of "frumentarii" was established. Based in Rome, it was under the command of a senior centurion, the "princeps frumentariorum". According to Aurelius Victor, the "frumentarii" were set up "to investigate and report on potential rebellions in the provinces" (presumably by provincial governors) i.e. they performed the function of an imperial secret police (and became widely feared and detested as a result of their methods, which included assassination). Although doubtless well-informed about events in the border-provinces through their network of local agents and spies, it appears that the "frumentarii" never expanded beyond internal security to fulfil a systematic military intelligence role.


title: Imperial Roman army

text: The lack of independent military intelligence, coupled with the slow speeds of communication, prevented the emperor and his "consilium" from exercising anything but the most general control over military operations in the provinces. Typically, a newly appointed governor would be given a broad strategic direction by the emperor, such as whether to attempt to annex (or abandon) territory on their province's borders or whether to make (or avoid) war with a powerful neighbour such as Parthia. For example, in Britain, the governor Gnaeus Julius Agricola appears to have been given approval for a strategy of subjugating the whole of Caledonia (Scotland) by Vespasian, only to have his gains abandoned by Domitian after AD 87, who needed reinforcements on the Danube front, which was threatened by the Sarmatians and Dacians. However, within these broad guidelines, the governor had almost complete autonomy of military decision-making.


title: Imperial Roman army

text: In those provinces that contained military forces, the governor's immediate subordinates were the commanders ("legati legionis") in command of the legions stationed in the province (e.g. in Britain, three "legati" reported to the governor). In turn, the legionary commander was reported to by the combat-unit commanders: the "centuriones pili priores" in command of the legion's cohorts and the "praefecti", in command of the auxiliary regiments attached to the legion. The empire's high command structure was thus remarkably flat, with only four reporting levels between combat-unit commanders and the emperor.


title: Imperial Roman army

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


title: Imperial Roman army

text: A critical advantage enjoyed by the imperial army over all its foreign enemies except the Parthians was a highly sophisticated organisation to ensure that the army was properly supplied on campaign. Like their enemies, the army would rely as much as possible on foraging for supplies when campaigning on enemy soil, but this was impractical in winter or even in summer if the land was barren or the enemy employed "scorched-earth" tactics. On Roman territory, foraging was obviously undesirable. The empire's complex supply organisation, as set up under Augustus, enabled the army to campaign in all seasons and in enemy territory. The quantities of food supplies required by an army on campaign were enormous and would require lengthy and elaborate planning for major campaigns. An imperial legion of 5,500 men would require a minimum of 12.5 tonnes of grain-equivalent "every day". Thus, Agricola's Caledonian task-force at the Battle of Mons Graupius, around 25,000-strong, would have required, c. 5,000 tonnes of grain-equivalent for three months' campaigning (plus fodder for the horses and pack animals).


title: Imperial Roman army

text: Such vast cargoes would be carried by boat as far as possible, by sea and/or river, and only the shortest possible distance overland. That is because transport on water was in ancient times much faster and more economical than on land (as it remains today, although the differential is smaller). Land transport of military supplies on the "cursus publicus" (imperial transport service) was typically on wagons ("angariae"), with a typical payload of 650 kg, drawn by two pairs of oxen. During the Principate, large vessels of several hundred tonnes' capacity were not uncommon. A vessel of, say 200 tonnes' capacity, with a 20-man crew, could carry the same load as c. 300 wagons (which required 300 drivers and 1,200 oxen, plus pay for the former and fodder for the animals). A merchant ship would also, with a favourable wind, typically travel three times faster than the typical achieved by the wagons and for as long as there was daylight, whereas oxen could only haul for at most five hours per day. Thus freighters could easily cover per day, compared to c. by the wagons. However, freighters of this capacity were propelled by square sails only and could progress only if there was a following wind, and could spend many days in port waiting for one. (However, coastal and fluvial freighters called "actuariae" combined oars with sail and had more flexibility, but smaller capacity, typically 30-40 tonnes). Maritime transport was also completely suspended for at least four months in the winter (as stormy weather made it too hazardous) and even during the rest of the year, shipwrecks were common. Even so, surviving shipping-rates show that it was cheaper to transport a cargo of grain by sea from Syria to Lusitania (i.e. the entire length of the Mediterranean – and a ways beyond – c. 5,000 km) than just overland.


title: Imperial Roman army

text: Rivers constituted the vital supply arteries of the army. The establishment of the Rhine-Danube line as the European border of the empire was thus primarily due to its value as a major fluvial supply route, rather than its defensibility. The Rhine and Danube rivers were dotted with purpose-built military docks ("portus exceptionales"). The protection of supply convoys on the rivers was the responsibility of the fluvial flotillas ("classes") under the command of the governors of provinces along the rivers: by AD 68, and perhaps from the time of Augustus, flotillas had been established on the Rhine ("classis germanica") and Danube ("classis Histrica").


title: Imperial Roman army

text: A grain cargo would first be transported from its region of origin (e.g. from the northern Black Sea region or Egypt) by large seagoing freighter to a port at the mouth of a navigable river (e.g. the Danube). There it would be transferred to a number of smaller-capacity fluvial "actuariae", which would transport it up-river to the grain-dock of a legionary fortress. The cargo would then be stored in a purpose-built granary within the fortress, where it would be safe from contamination or decay until it was needed. At the start of the campaigning season, it would be transported, still by river if possible, otherwise overland on wagons, to the tactical base used for operations. From there the campaigning legion would haul its own supplies to its current marching-camp. This was accomplished by a legion's mule-train of c. 1,400 mules. (In addition, each of the legion's 600 "contubernia" – 8-man platoons who shared a campaign-tent – possessed one or two mules to carry its tent and other equipment).


title: Imperial Roman army

text: The driving of the supply mule-train, and the care of the pack-animals, was in the hands of the legion's "calones", professional camp-servants, most likely also on the army pay-roll, who accompanied the unit everywhere on campaign. These men were armed as light infantry and given basic combat-training, so that they could protect the mule-train and, in emergencies, the marching-camp itself. 200-300 "calones" would accompany each legion. ("Calones" were distinct from the personal servants – slaves or freedmen – whom officers generally took with them on campaign).


title: Imperial Roman army

text: Beyond marching- and training-camps, the imperial army constructed various types of permanent fortifications: the legionary fortress ("castra legionaria"), designed to accommodate an entire legion of 5,000–6,000 men; the auxiliary fort ("castellum"), which normally held an auxiliary regiment of c. 500 men; smaller forts for detachments; watch-towers and signal-stations; border barriers ditches or ramparts; city walls; infrastructure, such as bridges, grain and arms depots, etc.


title: Imperial Roman army

text: In the 1st century, army fortifications predominantly consisted of earthen ramparts, topped by wooden parapets. Using commonly available materials, these were cheap and quick to construct and provided effective protection, especially from tribal enemies with no artillery or siegecraft skills. However, this type of fortification required constant maintenance: the rampart was vulnerable to soil-slides caused by torrential downpours and to the action of burrowing animals. The wooden parapet was vulnerable to rot, and to heavy missiles launched from catapults and, in dry conditions, to incendiary missiles. From around AD 50, when the empire's borders had begun to stabilise, the army started building fortifications of stone. These were much more expensive and time-consuming to erect, but were invulnerable to most natural threats (except earthquakes), provided much better protection against missiles and needed far less maintenance (many, such as Hadrian's Wall, would still be largely intact today if they had not been pillaged for their dressed stones over the centuries). However, earth-and-wood fortifications remained an important part of the empire's defences until c. AD 200, when stone fortifications became the norm.


title: Imperial Roman army

text: The first global estimate for the size of the imperial army in the ancient sources is in the "Annales" of Tacitus. In AD 23, shortly after the end of the rule of Augustus, there were 25 legions (about 125,000 men) and "roughly the same number again of auxiliaries" in about 250 regiments.


title: Imperial Roman army

text: From this base-line of c. 250,000 effectives, the imperial army grew steadily in the 1st and 2nd centuries, almost doubling in size to c. 450,000 by the end of the rule of Septimius Severus (AD 211). The number of legions increased to 33, and auxiliary regiments even more sharply to over 400 regiments. The army under Severus probably reached its peak size for the Principate period (30 BC – AD 284).


title: Imperial Roman army

text: In the late 3rd century, it is likely that the army suffered a sharp decline in numbers due to the Crisis of the Third Century (235–70) a period of numerous civil wars, major barbarian invasions and above all, the Plague of Cyprian, an outbreak of smallpox which may have eliminated as many as a third of the army's effectives. It is possible that, by AD 270, the army was not much greater than in AD 24. From this low point it seems that numbers were substantially increased, by at least a third, under Diocletian (): John the Lydian reports at some point in his reign the army totalled 389,704 men – restoring overall strength to the level attained under Hadrian.


title: Imperial Roman army

text: Army costs thus rose only moderately as a share of GDP between 14 and 150 AD, despite a major increase in army effectives of c. 50%. This is because the empire's population, and therefore total GDP, also increased substantially (by c. 35%). Thereafter, the army's share of GDP leapt by almost half, although army numbers increased only c. 15%. This is due to the Antonine plague, which is estimated by epidemiological historians to have reduced the empire's population by 15-30%. Nevertheless, even in 215, the Romans spent a similar proportion of GDP on defence than today's global superpower, the United States of America (which spent c. 3.5% in 2003). But the effective burden on taxpayers in an unmechanised agricultural economy with little surplus production (80% of the population depended on subsistence agriculture and a further 10% were on subsistence income), would have been relatively far heavier. Indeed, a study of imperial taxes in Egypt, by far the best-documented province, concluded that the burden was relatively severe.


title: Imperial Roman army

text: Military spending swallowed up c. 50-75% of total government budget, as there was little "social" spending, the main items of the latter consisting of prestige construction projects in Rome and the provinces; grain-dole and cash-handouts for Rome's proletariat; and subsidies to Italian families (similar to modern child benefit), to encourage them to produce more children. Augustus instituted this policy, with a one-off payment of 250 "denarii" per child. (Additional subsidies to poor Italian families, known as "alimenta", were introduced by Trajan).


title: Imperial Roman army

text: The Roman army had a strong interest in looking after the health of its effectives and developed a sophisticated medical service, based on the best medical knowledge and practice of the ancient world (i.e. Greek medicine). The Roman army's medics were highly skilled and possessed enormous practical experience. Although their knowledge was entirely empirical, not analytical, their practices were rigorously tried-and-tested on the battlefield and thus more effective than those available to most armies before the 19th century. (Roman army medics were, for example, far more competent than the "quacks" of the 17th and 18th centuries with their lethal practices such as bleeding).


title: Imperial Roman army

text: As with much of the imperial army's organisation, it was Augustus who, drawing on the evolved but "ad hoc" practices of the Republican army, established systematic medical services for the army, with a formal medical hierarchy and the construction of large, fully staffed and well-supplied military hospitals ("valetudinaria") in legionary bases e.g. the fully excavated hospital at "Castra Vetera" (Xanten, Rhineland).


title: Imperial Roman army

text: In overall charge of the legion's medical staff and services was the legion's executive officer, the "praefectus castrorum". Directly under him was the "optio valetudinarii", or director of the hospital in the legionary fortress, who would have overall charge of its administration and staff. However, the clinical head of the legion's medical service was the chief physician, called simply the "Medicus" (the capital "M" here is used to distinguish from several other ranks of "medicus"). Most often an ethnic-Greek from the eastern part of the Empire, the "Medicus" was generally a highly qualified practitioner, occasionally even a published academic. The most notable example is Pedanius Dioscorides, an army surgeon in the time of Nero, who published "Materia Medica", which remained for centuries the standard textbook on medicine. The rank of the "Medicus" is uncertain, but was probably on a par with the military tribunes i.e. equestrian. In many cases, the "Medicus" served a short commission, in the role of senior medical consultant, and then returned to civilian life.


title: Imperial Roman army

text: Reporting to the chief physician were 10 "medici ordinarii", qualified medics who were charged with the care of the men of each cohort. These held the rank of centurion. These were trained to handle the whole range of troops' medical problems, but specialists are attested e.g. "medicus chirurgus" (surgeon) and a "medicus ocularis" (ophthalmologist) in the "classis Britannica" (Channel fleet). Underneath the "ordinarii" were medical orderlies, some of whom held the rank of "principales", the rest as "milites immunes". The latter included "capsarii" (wound-dressers, from "capsa", a type of box in which they carried bandages) and "seplasarii" ("ointment-men"), who administered medicines.


title: Imperial Roman army

text: Auxiliary regiments had their own medics, although on a smaller scale than a legion's. Because of the smaller size of units, there was no equestrian chief physician, but a "medicus ordinarius". Also attested are medics who ranked as "principales", including a "veterinarius" in charge of animal welfare, as well as "immunes" on the bottom rung.


title: Imperial Roman army

text: From Greek medical science, Roman army medics inherited a wide knowledge of the medicinal properties of plants and herbs e.g. centaury, which was effective in healing wounds and eye diseases. Forts received regular supplies of medicines, and medics also composed herbal remedies themselves. Remains of at least five medicinal plants have been found in fort sites, suggesting that herb-gardens were cultivated inside fort precincts.


title: Imperial Roman army

text: On the battlefield, medics and orderlies would be on hand behind the lines to treat injured soldiers on the spot. Using a wide range of sophisticated surgical instruments, medics would promptly remove extraneous bodies such as arrow- and spear-heads, clean and disinfect wounds using clean water and medicated wine or beer and stitch them. Orderlies would then bandage them. Speed in cleaning, closing and bandaging the wound was critical, as, in a world without antibiotics, infection was the gravest danger faced by injured troops, and would often result in a slow, agonising death.


title: Imperial Roman army

text: Explanation of modern rank comparisons: It is difficult to find precise modern equivalents to the ranks of an ancient, unmechanised army in which aristocratic birth was a pre-requisite for most senior positions. Thus such comparisons should be treated with caution. Nevertheless, some approximate parallels can be found. The ones presented here are based on rank-comparisons used in Grant's translation of the "Annales" by Tacitus.


title: Imperial Roman army

text: As they mostly rose from the ranks, centurions are compared to modern sergeants-major, the most senior officers without a commission. An ordinary centurion was in command of a "centuria" of 80 men, equivalent to a company in a modern army, and is thus comparable to a British company sergeant-major (U.S. first sergeant). Senior centurions, known as "primi ordinis" ("of the first order"), consisted of the five commanders of the double-strength "centuriae" of the First Cohort (160 men each); and the nine "pilus prior" centurions (commanders of the 1st "centuria" of each cohort), who in the field are generally presumed by scholars to have been the actual (though not official) commanders of their whole cohort of 480 men, equivalent to a modern battalion. A senior centurion is thus likened to a British regimental sergeant-major (U.S. command sergeant major), the most senior non-commissioned officer in a battalion. The "primus pilus", the chief centurion of the legion, has no clear parallel.


title: Imperial Roman army

text: From the centurionate, the rank-structure jumps to the military tribunes, aristocrats who were directly appointed senior officers and thus comparable to modern commissioned officers. Although primarily staff-officers, in the field tribunes could be placed in command of one or more cohorts (Praetorian Guard cohorts were commanded by tribunes, and in the auxilia, a "praefectus", equivalent in rank to a tribune, commanded a cohort-sized regiment). These officers are thus comparable to modern colonels, who normally command battalions or regiments in a modern army. Finally, the "legatus legionis " was in command of the whole legion (over 5,000 men, equivalent to a modern brigade), plus roughly the same number of auxiliaries in attached regiments, bringing the total to c. 10,000 men, equivalent to a modern division. Thus a "legatus" is comparable to a modern general officer. The legions thus lacked any equivalent to modern junior commissioned officers (lieutenant to major). This is because the Romans saw no need to complement their centurions, who were considered fully capable of field commands, with commissioned officers. As a consequence, a chief centurion promoted to "praefectus castrorum" would, in modern terms, leap from sergeant-major to the rank of colonel in one bound.


title: Imperial Roman army

text: As had been the case during the Republic, the legions of the Principate era recruited Roman citizens exclusively. In the 1st and 2nd centuries, these represented a minority of the empire's inhabitants (about 10–20%). From the time of Augustus, legionary recruitment was largely voluntary. Republican-style conscription of citizens was only resorted to during emergencies which demanded exceptionally heavy recruitment, such as the Illyrian revolt (AD 6–9).


title: Imperial Roman army

text: Once the borders of the empire stabilised in the mid-1st century, most legions were based in particular provinces long-term. The number of Italian-born recruits dwindled. According to one survey, c. 65% were Italian-born in the early Julio-Claudian period (to AD 41), 49% in the period 42–68, 21% in the Flavian era (69–96) and around 8% under Hadrian. Italians thus represented c. 4% of total army recruits under Hadrian, if one takes into account the auxilia, despite constituting c. 12% of the empire's population, and well over 50% of its citizen-body, in 164. However, it should be borne in mind that many legionary recruits born outside Italy were residents of Roman colonies originally established to settle legionary veterans. As descendants of the latter, such recruits were, at least partially, of Italian blood; e.g. the emperor Hadrian, who was born in the Roman colony of "Italica" in Spain and whose father was of Italian descent while his mother is thought to have been of local Iberian origin. However, the proportion of legionaries of Italian blood dropped still further as the progeny of auxiliary veterans, who were granted citizenship on discharge, became a major source of legionary recruits. It was probably to redress this shortfall that Marcus Aurelius, faced with a major war against the Marcomanni, raised two new legions in 165, "II Italica" and "III Italica", apparently from Italian recruits (and presumably by conscription).


title: Imperial Roman army

text: A major recruitment problem for the legions was that the host provinces often lacked a sufficiently large base of citizens to satisfy their recruitment needs. For example, the Roman Britain province, where Mattingly doubts that the three legions deployed could fill their vacancies from a citizen-body of only c. 50,000 in AD 100 (less than 3% of about two million total inhabitants). This implies that the British legions must have drawn many recruits from elsewhere, especially from northern Gaul.


title: Imperial Roman army

text: The frontier legions' recruitment problems have led some historians to suggest that the rule limiting legionary recruitment to citizens was largely ignored in practice. But the evidence is that the rule was strictly enforced e.g. the recorded case of two recruits who were sentenced to be flogged and then expelled from a legion when it was discovered that they had lied about their status. The only significant exception to the rule appears to have concerned the sons of legionaries. From the time of Augustus until the rule of Septimius Severus (), serving legionaries were legally prohibited from marrying (presumably so as to discourage them from deserting if they were deployed far from heir families). However, with most legions deployed in the same bases long-term, legionaries often did develop stable relationships and bring up children. The latter, although of Roman blood, were illegitimate in Roman law and thus could not inherit their fathers' citizenship. Nevertheless, it appears that the sons of serving legionaries were routinely recruited, perhaps through the device of granting them citizenship when they enlisted.


title: Imperial Roman army

text: In the 1st century, the vast majority of auxiliary common soldiers were recruited from the Roman "peregrini" (second-class citizens). In the Julio-Claudian era (to AD 68), conscription of "peregrini" seems to have been practiced, probably in the form of a fixed proportion of men reaching military age in each tribe being drafted, alongside voluntary recruitment. From the Flavian era onwards, it appears that the auxilia were, like the legions, a largely volunteer force, with conscription resorted to only in times of extreme manpower demands e.g. during Trajan's Dacian Wars (101–106). Although recruits as young as 14 are recorded, the majority of recruits (66%) were from the 18–23 age group.


title: Imperial Roman army

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


title: Imperial Roman army

text: About fifty auxiliary regiments founded by Augustus were, exceptionally, recruited from Roman citizens. This was due to the emergency manpower requirements of the Illyrian revolt (AD 6–9), which was described by the Roman historian Suetonius as the most difficult conflict Rome had faced since the Punic Wars. Although the Republican minimum property requirement for admission to the legions had long since been abandoned, citizens who were vagrants, convicted criminals, undischarged debtors, or freed slaves (Roman law accorded citizenship to the freed slaves of Roman citizens) were still excluded. Desperate for recruits, Augustus had already resorted to the compulsory purchase and emancipation of thousands of slaves for the first time since the aftermath of the Battle of Cannae two centuries earlier. But the emperor found the idea of admitting such men to the legions unpalatable. Therefore, he formed separate auxiliary regiments from them. These units were accorded the title "civium Romanorum" ("of Roman citizens"), or "c.R." for short. After the Illyrian revolt, these cohorts remained in being and recruited "peregrini" like other auxiliary units, but retained their prestigious "c.R." title. Subsequently, many other auxiliary regiments were awarded the "c.R." title for exceptional merit, an award that conferred citizenship on all their currently serving members.


title: Imperial Roman army

text: Apart from the citizen-regiments raised by Augustus, Roman citizens were regularly recruited to the auxilia. Most likely, the majority of citizen-recruits to auxiliary regiments were the sons of auxiliary veterans who were enfranchised on their fathers' discharge. Many such men may have preferred to join their fathers' old regiments, which were a kind of extended family to them, rather than join a much larger, unfamiliar legion. Legionaries frequently transferred to the auxilia (mostly promoted to a higher rank). The incidence of citizens in the auxilia would thus have grown steadily over time until, after the grant of citizenship to all "peregrini" in 212, auxiliary regiments became predominantly, if not exclusively, citizen units.


title: Imperial Roman army

text: It is less clear-cut whether the regular auxilia recruited "barbari" (barbarians, as the Romans called people living outside the empire's borders). Although there is little evidence of it before the 3rd century, the consensus is that the auxilia recruited barbarians throughout their history. In the 3rd century, a few auxilia units of clearly barbarian origin start to appear in the record e.g. "Ala I Sarmatarum", "cuneus Frisiorum" and "numerus Hnaufridi" in Britain.


title: Imperial Roman army

text: At the bottom end of the rank pyramid, rankers were known as "caligati" (lit: "sandalled men" from the "caligae" or hob-nailed sandals worn by soldiers), or simply as "milites" ("soldiers"). Depending on the type of regiment they belonged to, they held the official ranks of "pedes" (foot-soldier in a legion or auxiliary "cohors"), "eques" (cavalryman in legionary cavalry or an auxiliary "cohors equitata") and "eques alaris" ("ala" cavalryman). A new recruit under training was known as a "tiro", and received half-pay.


title: Imperial Roman army

text: Soldiers' working lives were arduous. As well as facing the hardships of military discipline and training, and the dangers of military operations, soldiers fulfilled a large number of other functions, such as construction workers, policemen, and tax collectors (see below, Everyday life). It has been estimated from the available data that only an average of c. 50% of recruits survived their 25-year term of service. This mortality rate was well in excess of the contemporary demographic norm for the 18–23 age-group. An indication of the rigours of military service in the imperial army may be seen in the complaints aired by rebellious legionaries during the great mutinies that broke out in the Rhine and Danube legions on the death of Augustus in AD 14.


title: Imperial Roman army

text: "Old men, mutilated by wounds are serving their 30th or 40th year. And even after your official discharge, your service is not finished. For you stay on with the colours as a reserve, still under canvas - the same drudgery under another name! And if you manage to survive all these hazards, even then you are dragged off to a remote country and settled in some waterlogged swamp or untilled mountainside. Truly the army is a harsh, unrewarding profession! Body and soul are reckoned at two and a half "sesterces" a day - and with this you have to find clothes, weapons, tents and bribes for brutal centurions if you want to avoid chores. Heaven knows, lashes and wounds are always with us! So are hard winters and hardworking summers..."


title: Imperial Roman army

text: "The soldiers' reply was to tear off their clothes and point to the scars left by their wounds and floggings. There was a confused roar about their wretched pay, the high cost of exemptions from duty, and the hardness of the work. Specific reference was made to earthworks, excavations, foraging, collecting timber and firewood..."


title: Imperial Roman army

text: Basic legionary pay was set at 225 "denarii" per annum under Augustus. Until at least AD 100, auxiliary soldiers were apparently paid less than their legionary counterparts. In the early Julio-Claudian period, it has been suggested that an auxiliary foot-soldier was paid only a third the rate of a legionary (although an "eques alaris" was paid two-thirds). By AD 100, the differential had narrowed dramatically. An auxiliary "pedes" was paid 20% less than his legionary counterpart at the time of Domitian () (but an "eques cohortalis" the same and an "eques alaris" 20% more).


title: Imperial Roman army

text: General military pay was increased by 33% "denarii" under Domitian (r.81-96). Septimius Severus (r. 197–211) increased the rate by a further 25%, and then his successor Caracalla (r. 211–8) by 50% again. But in reality, these pay rises only more-or-less covered price inflation over this period, which is estimated at c. 170% by Duncan-Jones. Since the debasement of the central silver coinage, the "denarius", roughly reflected general inflation, it can be used as a rough guide to the real value of military pay:


title: Imperial Roman army

text: Furthermore, a soldier's gross salary was subject to deductions for food and equipment. The latter included weapons, tents, clothing, boots and hay (probably for the company mules). These deductions would leave the 1st-century legionary with a modest disposable income of c. 115 "denarii", and an auxiliary 78 "denarii".


title: Imperial Roman army

text: A legionary's daily pay-rate of 2.5 "sesterces" was only marginally greater than a common day-labourer in Rome could expect in this period (typically two "sesterces" per day). Such modest remuneration for a tough service raises the question of how the imperial army succeeding in raising sufficient volunteers with only the occasional recourse to conscription. The reason is that the comparison with a Rome day-labourer is misleading. The vast majority of the army's recruits were drawn from provincial peasant families living on subsistence farming i.e. farmers who after paying rent, taxes and other costs were left with only enough food to survive: the situation of c. 80% of the Empire's population. To such persons, any disposable income would appear attractive, and the physical rigours of army service no worse than back-breaking drudgery in the fields at home. In any case, where a peasant family had more children than its plot of land could support, enlistment of one or more sons in the military would have been a matter of necessity, rather than choice.


title: Imperial Roman army

text: In addition, soldiers enjoyed significant advantages over day-labourers. They had job security for life (assuming they were not dishonourably discharged). Legionaries could count on irregular but substantial cash bonuses ("donativa"), paid on the accession of a new emperor and on other special occasions; and, on completion of service, a substantial discharge-bonus ("praemia") equivalent to 13 years' gross pay, which would enable him to buy a large plot of land. Auxiliaries were exempt from the annual poll-tax payable by all their fellow-"peregrini" and were rewarded on discharge with Roman citizenship for themselves and their heirs. Duncan-Jones argues that, at least from the time of Hadrian, auxiliaries also received "donativa" and "praemia". Finally, a ranker had a one in twenty chance of increasing his pay by 50-100% by gaining promotion to the rank of "principalis" or junior officer. Out of 480 men, a typical cohort would contain 24 junior officers (other than specialists).


title: Imperial Roman army

text: The great mutinies of AD 14, which were about pay and conditions – as distinct from later revolts in support of a contender for the imperial throne – were never repeated. The reason they occurred at all was probably because, at the time, many legionaries were still conscripts (mostly enlisted during the Illyrian revolt crisis of AD 6–9) and the majority still Italians. This made them far less tolerant of the hardships of military life than provincial volunteers. Italians were by this stage used to a higher standard of living than their provincial subjects, largely due to a massive effective subsidy by the latter: Italians had long been exempt from direct taxation on land and heads and, at the same time, rents from the vast imperial and private Roman-owned estates carved out by conquest in the provinces largely flowed to Italy. Thus, a central demand of the 14 CE mutineers was that legionary pay be increased from 2.5 to 4 "sesterces" (1 "denarius") per day. This was conceded by Tiberius in order to pacify the mutiny, but soon revoked as unaffordable, and pay remained at roughly the same real level into the 3rd century.


title: Imperial Roman army

text: Rankers with specialist skills were classed as "milites immunes" ("exempt soldiers"), meaning that they were exempt from the normal duties of their fellow-soldiers so that they could practice their trade. A legion would contain over 600 "immunes". Over 100 specialist jobs are attested, including the all-important blacksmiths ("fabri"), among whom the "scutarii" ("shield-men"), probably smiths that specialised in weapons manufacture or repair, and other craftsmen who worked in the "fabrica"; "carpentarii" ("wagon-makers/repairers", or, generally, "carpenters"); "capsarii" (wound-dressers) and "seplasiarii" ("ointment-men"), medical orderlies who worked in the "valetudinarium" (hospital in a legionary fortress) or "hospitium" (auxiliary fort hospital); "balniator" (bath attendant); and "cervesarius" (beer-brewer). It is uncertain, however, whether the latter two jobs were held by "milites immunes" or by civilians working for the unit on contract. "Immunes" were on the same pay-scale as other rankers.


title: Imperial Roman army

text: Below centurion rank, junior officers in the "centuria" were known as "principales". "Principales", together with some specialists, were classified in two pay-scales: "sesquiplicarii" ("one-and-a-half-pay soldiers") and "duplicarii" ("double-pay soldiers"). These ranks probably most closely resembled the modern ranks of corporal and sergeant respectively. A higher rank of "triplicarius" ("triple-pay soldier") is attested very rarely in the 1st century and this pay-scale was probably short-lived. "Sesquiplicarii" included the "cornicen" (horn-blower), who blew the "cornu", a long, three-piece circular horn. Above him was the "tesserarius" (literally "tablet-holder", from "tessera" = "wax tablet", on which the daily password was inscribed), who was the officer of the watch. "Duplicarii", in ascending order of rank, were the "optio", or centurion's deputy, who was appointed by his centurion and would expect to succeed him when the latter was promoted. While a centurion led his unit from the front in battle, his "optio" would bring up the rear. Responsible for preventing rankers from leaving the line, the "optio" was equipped with a long, silver-tipped stave which was used to push the rear ranks forward. Ranking just below centurion was the "signifer" (standard-bearer), who bore the "centuria"'s "signum". In the field, the "signifer" wore the skin of a wolf's head over his own. At the legionary level, the "vexillarius" had charge of the commander's "vexillum", or banner, and accompanied the "legatus" in the field. The "aquilifer" bore the legion's "aquila" standard, and wore a lion's head. He accompanied the chief centurion, as did the legion's "imaginifer", who bore a standard with the emperor's image. All these standard-bearers were "duplicarii".


title: Imperial Roman army

text: Between junior officers ("principales") and senior officers ("tribuni militum"), the Roman army contained a class of officers called centurions ("centuriones", singular form: "centurio", literally "commanders of 100 men") in the infantry and decurions ("decuriones", singular form "decurio", literally "commanders of 10 men") in the auxiliary cavalry. These officers commanded the basic tactical units in the army: a centurion headed a "centuria" (company, 80 men-strong) in the infantry (both legionary and auxiliary) and a decurion led a "turma" (squadron, 30-men strong) in the auxiliary cavalry (in the small contingents of legionary cavalry, squadron-leaders were called centurions). Broadly speaking, centurions and decurions were considered to be of corresponding rank.


title: Imperial Roman army

text: The great majority of rankers never advanced beyond "principalis". The few who did became centurions, a rank they would normally attain after 13–20 years of service to reach this level. Promotion to the centurionate, known to the Romans simply as the "ordo", or "rank", was normally in the hands of the "legatus legionis". However, the latter occasionally followed the Republican tradition and allowed the men of a "centuria" to elect their own centurion. Although most centurions rose from the ranks, there are a few instances attested of young men who were directly appointed centurions on enlistment: these were mostly the sons of active or retired centurions.


title: Imperial Roman army

text: Centurions were arguably the most important group of officers in the army, as they led the legions' tactical sub-units (cohorts and "centuriae") in the field. In consequence, on becoming a centurion, a soldier's pay and prestige would undergo a quantum-leap. Centurions were paid far more than their men. The available evidence is scant, but suggests that, in the 2nd century, an ordinary centurion was paid 16 times the pay of a ranker. If so, the differential had widened dramatically since the days of the Punic Wars, when a centurion was paid just double the rate of a ranker i.e. was a "duplicarius" in imperial terms. By the time of Caesar, the standing of centurions had already greatly increased: in 51 BC, after an especially tough campaign during the Gallic War, Caesar promised his troops a bonus of 50 "denarii" per man, and 500 each to the centurions, indicating that a differential of 10 times was commonplace even in the late Republic.


title: Imperial Roman army

text: Each legion contained 60 (later 59) centurions, ranked in an elaborate hierarchy. Each of the 10 cohorts was ranked in seniority, the 1st Cohort (whose "centuriae", after about AD 80, were double-strength) being the highest. Within each cohort, each of its six "centuriae", and thus of its commanding centurion, was likewise ranked. Within this hierarchy, three broad ranks can be discerned: centurions ("centuriones ordinarii"), senior centurions ("centuriones primi ordinis" or "first-rank centurions") and the legion's chief centurion ("centurio primus pilus"). Senior centurions included those in command of the five "centuriae" in the 1st Cohort and the "centuriones pilus prior" ("front-spear") centurions of the other nine cohorts (i.e. the centurions in command of the 1st "centuria" of each cohort, who many historians believe, was also in "de facto" command of the whole cohort).


title: Imperial Roman army

text: All centurions, including the "primus pilus", were expected to lead their units from the front, on foot like their men, and were invariably in the thick of any combat melee. As a consequence, their casualty rates in battle were often heavy. An example from Caesar's "De Bello Gallico", during a battle against the Belgic tribes of northern Gaul (57 BC): "Caesar had gone to the right wing, where he found the troops in difficulties... All the centurions of the 4th cohort [of the 12th legion] were dead, and the standard lost; nearly all the centurions of the rest of the cohorts were either killed or wounded, including the chief centurion, P. Sextius Baculus, a very brave man, who was so disabled by serious wounds that he could no longer stand on his feet." Or again, in a later battle against Vercingetorix at "Gergovia" (52 BC): "Attacked from all sides, our men held their ground until they had lost 46 centurions..." In battle, centurions were also responsible for the security of their unit's standard, whose bearer, the "signifer", stayed close to his centurion on the battlefield. The chief centurion was accompanied by the "aquilifer" and had the even weightier responsibility of protecting the legion's "aquila" (eagle-standard).


title: Imperial Roman army

text: Centurions were also responsible for discipline in their units, symbolised by the "vitis" or vine-stick which they carried as a badge of their rank. The stick was by no means purely symbolic and was frequently used to beat recalcitrant rankers. Tacitus relates that one centurion in the army in Pannonia gained the nickname "Da mihi alteram!" ("Give-me-another!") for his propensity to break his stick over his men's backs and then shout at his "optio" to bring him a new one. Centurions often earned the hatred of their men, as shown during the great mutinies which broke out on the Rhine-Danube borders on the death of Augustus. In one legion, each centurion was given 60 lashes of the flail by the mutineers, to represent the legion's total number of centurions, and was then thrown into the Rhine to drown.


title: Imperial Roman army

text: Outside the military sphere, centurions performed a wide range of administrative duties at a senior level, which was necessary in the absence of an adequate bureaucracy to support provincial governors. A centurion might serve as a "regionarius", or supervisor of a provincial district, on behalf of the provincial governor. They were also relatively wealthy individuals, due to their high salaries. In retirement, they often held high civic positions in the councils of Roman "coloniae" (veterans' colonies).


title: Imperial Roman army

text: However, in social rank, the great majority of centurions were commoners, outside the small senatorial and equestrian elites which dominated the empire. In the class-conscious system of the Romans, this rendered even senior centurions far inferior in status to any of the legion's "tribuni militum" (who were all of equestrian rank), and ineligible to command any unit larger than a "centuria". This is probably the reason why a cohort did not have an official commander. (However, many historians believe that a cohort in the field was under the de facto command of its leading centurion, the "centurio pilus prior", the commander of the cohort's 1st "centuria"). Until c. AD 50, centurions had been able to command auxiliary regiments, but the emperor Claudius restricted these commands to Knights. The only escape-route for centurions from this "class-trap" was to reach the highest grade of "centurio primus pilus". On completing his single-year term of office, the chief centurion of each legion (i.e. some 30 individuals each year) was elevated to the Order of Knights by the emperor.


title: Imperial Roman army

text: Normally, an outgoing "primus pilus" (known as a "primipilaris") would be promoted to "praefectus castrorum" (quartermaster and third officer) of a legion or to prefect of an auxiliary regiment or to tribune of a Praetorian cohort in Rome. Beyond these posts, the senior command-positions reserved for knights were in theory open to "primipilares": command of the imperial fleets and of the Praetorian Guard, and the governorships of equestrian provinces (most importantly, Egypt). But in practice, "primipilares" rarely progressed to these posts due to their age (unless they were in the minority of centurions directly appointed as young men). It would take a ranker a median of 16 years just to reach centurion-rank and probably the same again to reach "primus pilus". Most "primipilares" would thus be in their 50s when elevated to the Order of Knights, and already eligible for retirement, having completed 25 years' service. (In contrast, hereditary knights would be appointed to military tribunates of a legion and command of auxiliary regiments in their 30s, leaving plenty of time to move on to the senior posts).


title: Imperial Roman army

text: Each legion contained six senior officers, five of equestrian and one of senatorial rank, called "tribuni militum" ("tribunes of the soldiers"). The title "tribune" derives from the fact that in Republican days, they were elected by the Roman people's assembly ("comitia centuriata") from the ranks of Roman knights. The elected officers would stand on the "tribunal" (dais). Originally the elected tribunes took turns to command their legion in pairs (see Roman army of the mid-Republic). Under Julius Caesar, command of legions became informally entrusted to single officers dubbed "legati" ("chosen ones") appointed by the proconsul, or governor, of the province in which the legions were stationed. This position was formalised under Augustus.


title: Imperial Roman army

text: In the imperial army, the tribunes thus became staff-officers to the "legatus". Formally, tribunes were entrusted with the legion's administration and paperwork, for which purpose they were each provided with a small personal staff of "principales" and military clerks ("cornicularii"). Tribunes' military role was apparently kept ill-defined and flexible, so as to provide the legion commander with a small group of senior officers to carry out special tasks. Tribunes could be asked to command detachments of one or more cohorts; command specialist units, such as a flotilla; lead special operations; supervise fortification projects or the collection of supplies. In a pitched battle scenario, the available evidence does not permit a clear picture of a tribune's role. For example, Caesar relates (57 BC): "Noticing that the 7th legion, which was nearby, was also under heavy pressure, Caesar ordered the military tribunes to gradually join together the two legions [the 7th and the 12th] and form a square formation, so that they could advance against the enemy in any direction." Or again (52 BC): "Caesar ordered the trumpeters to sound the retreat and the 10th legion, which was with him, immediately halted their advance. But the other legions did not hear the signal, as they were separated by a wide depression, although the legates and military tribunes did their best to hold them back, in accordance with Caesar's orders." This evidence is consistent with two possible battle-roles for tribunes. A tribune may have played a formal role in command of a sector of the legion's battle-line. Alternatively, tribunes may have accompanied the "legatus" around the field, ready to convey his orders to particular senior centurions, or to assume command of a particular sector of the line at the behest of the "legatus". In either case, as Roman knights, tribunes would move around the battle-field on horseback, not on foot like the centurions, and they would generally remain outside the fray, in order to maintain a strategic overview of the field.


title: Imperial Roman army

text: The legion's five equestrian tribunes were known as "angusticlavii" ("narrow-banded", from the stripes a Roman knight was entitled to wear on his "tunica", which was narrower than a senator's). They differed from their senatorial colleague, the "laticlavius" ("broad-banded"), in age, rank and experience. Before embarking on their military service ("tres militiae"), their normal "cursus honorum" required them to perform the full range of administrative and religious posts in the council of their home city. Minimum-age limits for such posts implied that they would be at least 30 before starting the "tres militiae". By the time they became tribune of a legion, they would already have led an auxiliary cohort for three or four years, giving them substantial command experience.


title: Imperial Roman army

text: There is no evidence regarding the pay of military tribunes. But since they ranked on a level with the commanders of auxiliary regiments, who were paid c. 50 times more than rankers, it is safe to assume that tribunes were paid a similar multiple of legionary's pay. Tribunes' pay would in any case have fallen somewhere between the 16-multiple of centurions and the 70-multiple of "legati".


title: Imperial Roman army

text: The legion's third officer was the "praefectus castrorum" ("prefect of the camp"), a post mostly filled by former chief centurions. These would typically be in their 50s, having earned their equestrian status by a lifetime of experience at the sharp end of legionary activity. Officially, the role of the "praefectus" was, as the title implies, that of camp quartermaster, in charge of the legion's headquarters and supplies. But with their enormous experience, the "praefectus" role extended much further, to acting as executive officer to the "legatus", advising on all manner of military operations. In the absence of the "legatus", the "praefectus" would normally deputise for him, under the nominal command of the "laticlavius". From the time of Gallienus (), these officers were routinely placed in command of their legion.


title: Imperial Roman army

text: The legate's nominal second-in-command was the single military tribune of senatorial rank attached to the legion, the "laticlavius" (literally: "broad-banded", referring to the wide stripe men of senatorial rank wore on their "tunica"). Typically the son of a senator (sometimes the legate's own son), and aged in his early twenties, he was performing his military service before seeking election as "quaestor" and thereby gaining a seat in the Senate (for which the minimum age was 25 years). His lack of military experience did not prevent him leading important combat missions. In the highly status-conscious Roman social system, his high birth would have commanded the automatic respect of even the most experienced commoner.


title: Imperial Roman army

text: The commander of an imperial legion was known as the "legatus legionis". He was typically a senator of praetorian rank i.e. he had held the post of praetor, implying that he would normally be in his mid-30s. His military experience would be limited to that gained as serving in his early twenties as "tribunus laticlavius". As a consequence, he would rely heavily on the advice of his enormously experienced "praefectus castrorum". The evidence suggests that a "legatus" would be paid c. 70 times a ranker's salary.


title: Imperial Roman army

text: An auxiliary regiment's junior officers appear broadly the same as in the legions. These were, in ascending order: "tesserarius", "optio", "signifer" (standard-bearer for the "centuria"). However, auxiliary regiments also attest a "custos armorum" ("keeper of the armoury"), on pay-and-a-half. The "vexillarius", bore the regiment's standard, on double-pay. In addition, the "turma" of an "ala" appear to have contained a "curator" on double-pay, ranking just below decurion, apparently in charge of horses and caparison.


title: Imperial Roman army

text: In the early Julio-Claudian period, the commanders of the auxiliary units ("praefecti auxiliorum") were often senior centurions and so ranked below the legionary tribunes. The position changed under Claudius, who restricted command of auxiliary regiments to men of equestrian rank. Furthermore, an equestrian military "cursus honorum" became established, known as the "tres militiae" ("three commands"), each held for 3–4 years: command of an auxiliary cohort, followed by military tribune of a legion, followed by command of an "ala". These reforms had the effect of elevating "praefecti" to the same rank as legionary tribunes. Under Hadrian, a fourth "militia", command of a double-strength "ala milliaria" was established for especially proficient officers.


title: Imperial Roman army

text: It appears that in the 2nd century, the majority of auxiliary prefects were still of Italian origin. In contrast, the evidence for the 3rd century is that Italians provided less than a third of prefects.


title: Imperial Roman army

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


title: Imperial Roman army

text: The numbering of the legions is confusing, due to duplicated and inconsistent numeration by various emperors. Several legions shared the same serial number with others. Augustus numbered the legions he founded himself from I, but at the same retained the serial numbers of those legions he inherited from his predecessors. This policy was generally followed by those of his successors who also founded new legions (there were thus many legions numbered I). However, even this practice was not consistently followed. For example, Vespasian formed two new legions out of units disbanded in disgrace after the Civil War of 68–9, but gave them the same serial numbers (but different titles) as the disbanded ones. Trajan numbered the first legion he founded XXX because there were 29 other legions in existence at that time; but the second Trajanic legion was given the serial number II. XVII, XVIII and XIX, the numbers of the legions annihilated in the Teutoburg Forest, were never used again. (No titles are recorded in surviving ancient sources for these three legions, suggesting that their titles may have been deliberately suppressed due to their disgrace). As a result of this somewhat chaotic numeration, it became necessary to accord a title, as well as a serial number, to each legion in order to distinguish between legions with the same number. The geographical titles indicate (a) the country where a legion was originally recruited e.g. "Italica" = from Italy or (b) peoples the legion vanquished, e.g.,"Parthica" = victorious over the Parthians. Legions bearing the personal name of an emperor, or of his "gens" (clan) (e.g., "Augusta", "Flavia") were either founded by that Emperor or accorded the name as a mark of special favour.


title: Imperial Roman army

text: The nomenclature of the great majority of auxiliary regiments followed a standard configuration: unit type ("ala" or "cohors"), followed by serial number, followed by name of the "peregrini" tribe (or nation) from whom the regiment was originally raised, in the genitive (possessive) plural case e.g. "cohors III Batavorum" ("3rd Cohort of Batavi"); "cohors I Brittonum" ("1st Cohort of Britons"). Some regiments combine the names of two "peregrini" tribes, most likely after the merger of two previously separate regiments e.g. "ala I Pannoniorum et Gallorum" ("1st Wing of Pannonians and Gauls"). A minority of regiments are named after an individual, mostly after the first prefect of the regiment e.g. "ala Sulpicia" (presumably named after a prefect whose middle ("gens") name was Sulpicius). The latter is also an example of the minority of regiments that did not carry a serial number. After the tribal name, one or more epithets could be added, to further describe the regiment: "equitata" (infantry cohort with a cavalry contingent attached); "sagittariorum" (archer unit) etc.


title: Imperial Roman army

text: Legions often carried several titles, awarded after successive campaigns, normally by the ruling emperor, e.g., "XII Fulminata" also boasted: "paterna" ("senior"), "victrix" ("victorious"), "antiqua" ("venerable"), "certa constans" ("reliable, steadfast") and "Galliena" ("(the emperor) Gallienus's favourite"). "Pia fidelis" ("dutiful, loyal"), "fidelis constans" and others were titles awarded to several legions, sometimes several times to the same legion.


title: Imperial Roman army

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


title: Imperial Roman army

text: Each tactical unit in the imperial army, from "centuria" upwards, had its own standard. This consisted of a pole with a variety of adornments that was borne by dedicated standard-bearers who normally held the rank of "duplicarius". Military standards had the practical use of communicating to unit members where the main body of the unit was situated, so that they would not be separated, in the same way that modern tour-group guides use umbrellas or flags. But military standards were also invested with a mystical quality, representing the divine spirit ("genius") of the unit and were revered as such (soldiers frequently prayed before their standards). The loss of a unit's standard to the enemy was considered a terrible stain on the unit's honour, which could only be fully expunged by its recovery.


title: Imperial Roman army

text: The standard of a "centuria" was known as a "signum", which was borne by the unit's "signifer". It consisted of a pole topped by either an open palm of a human hand or by a spear-head. The open palm, it has been suggested, originated as a symbol of the maniple ("manipulus" = "handful"), the smallest tactical unit in the Roman army of the mid-Republic. The poles were adorned with two to six silver discs (the significance of which is uncertain). In addition, the pole would be adorned by a variety of cross-pieces (including, at bottom, a crescent-moon symbol and a tassel). The standard would also normally sport a cross-bar with tassels.


title: Imperial Roman army

text: The standard of a Praetorian cohort or an auxiliary cohort or "ala" was known as a "vexillum" or banner. This was a square flag, normally red in colour, hanging from a crossbar on the top of the pole. Stitched on the flag would be the name of the unit and/or an image of a god. An exemplar found in Egypt bears an image of the goddess Victory on a red background. The "vexillum" was borne by a "vexillarius". A legionary detachment ("vexillatio") would also have its own "vexillum". Finally, a "vexillum" traditionally marked the commander's position on the battlefield. The exception to the red colour appears to have been the Praetorian Guard, whose "vexilla", similar to their clothing, favoured a blue background.


title: Imperial Roman army

text: From the time of Marius (consul 107 BC), the standard of all legions was the "aquila" ("eagle"). The pole was surmounted by a sculpted eagle of solid gold, or at least gold-plated silver, carrying thunderbolts in its claws (representing Jupiter, the highest Roman god. Otherwise the pole was unadorned. No exemplar of a legionary eagle has ever been found (doubtless because any found in later centuries were melted down for their gold content). The eagle was borne by the "aquilifer", the legion's most senior standard-bearer. So important were legionary eagles as symbols of Roman military prestige and power, that the imperial government would go to extraordinary lengths to recover those captured by the enemy. This would include launching full-scale invasions of the enemy's territory, sometimes decades after the eagles had been lost e.g. the expedition in 28 BC by Marcus Licinius Crassus against Genucla (Isaccea, near modern Tulcea, Rom., in the Danube delta region), a fortress of the Getae, to recover standards lost 33 years earlier by Gaius Antonius, an earlier proconsul of Macedonia. Or the campaigns of AD 14–17 to recover the three eagles lost by Varus in AD 6 in the Teutoburg Forest.


title: Imperial Roman army

text: Under Augustus, it became the practice for legions to carry portraits ("imagines") of the ruling emperor and his immediate family members. An "imago" was usually a bronze bust carried on top of a pole like a standard by an "imaginifer".


title: Imperial Roman army

text: From around the time of Hadrian (r. 117–38), some auxiliary "alae" adopted the dragon-standard ("draco") commonly carried by Sarmatian cavalry squadrons. This was a long cloth wind-sock attached to an ornate sculpture of an open dragon's mouth. When the bearer ("draconarius") was galloping, it would make a strong hissing-sound.


title: Imperial Roman army

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


title: Imperial Roman army

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


title: Imperial Roman army

text: The basic equipment of an imperial foot-soldier was essentially the same as in the manipular Roman army of the Republic: metal armour cuirass, metal helmet, shield and sword. However, new equipment – the "lorica segmentata" and the rectangular version of the "scutum" – was developed for legionaries, although apparently not made available to auxiliaries.


title: Imperial Roman army

text: In the 2nd century, there is evidence of "fabricae" (arms factories) inside legionary bases and even in the much smaller auxiliary forts, staffed mainly by the soldiers themselves. But, unlike for the Late Roman army of the 4th century onwards, there is no evidence, literary or archaeological, of "fabricae" outside military bases and staffed by civilians during the Principate (although their existence cannot be excluded, as no archaeological evidence has been found for the late "fabricae" either).


title: Imperial Roman army

text: "Lorica segmentata": Modern tests have shown that this "lorica" provided better protection to weapon-blows and missile-strikes than the other types of metal armour commonly used by Roman troops, mail ("hamata") or scale ("squamata"), being virtually impenetrable by ancient weapons. However, historical re-enactors have found replicas of the "lorica" uncomfortable due to chafing and could only wear them for relatively short periods. It was also more expensive to manufacture and difficult to maintain due to its complex design of separate laminated strips held together by braces and hooks.


title: Imperial Roman army

text: The bas-reliefs of Trajan's Column, a monument erected in 113 in Rome to commemorate the conquest of Dacia by Emperor Trajan (), are a key source for Roman military equipment. Auxilia are generally shown wearing chain-mail or simple leather corslets, and carrying oval shields ("clipei"). Legionaries are depicted wearing "lorica segmentata" at all times (whether in combat or in other activities, such as construction) and with curved rectangular shields. But the figures in Trajan's Column are highly stereotyped, in order to distinguish clearly between different types of troops. On another Trajanic monument, the Adamclisi Tropaeum, the "lorica segmentata" does not appear at all, and legionaries and auxilia alike are depicted wearing either chain-mail or scales. There is general recognition that the Adamclisi monument is a more accurate portrayal of normality, with the "segmentata" used rarely, maybe only for set-piece battles and parades. It has been suggested that the "lorica" may have been used by auxiliaries also. But there is no firm evidence for this. Traces of this type of armour have been found in forts in Raetia from a time when no legions were stationed in the province. But these may simply have been left behind by legionaries on temporary detachment. Furthermore, auxilia are nowhere depicted wearing such armour.


title: Imperial Roman army

text: The provision of more protective and expensive armour to legionaries was probably due to non-military reasons: the army was highlighting their social superiority, just as it did with higher pay. During the 3rd century, when all "peregrini" were granted citizenship, and therefore legionaries lost their social superiority, the "lorica segmentata" and the rectangular shield disappeared.


title: Imperial Roman army

text: During the 3rd century, the "segmentata" appears to have been dropped and troops are depicted wearing chain mail (mainly) or scale, the standard armour of the 2nd century auxilia. Officers generally seem to have worn bronze or iron cuirasses, as during the Republic, together with traditional "pteruges".


title: Imperial Roman army

text: In the Julio-Claudian era (30 BC – AD 69), it appears that soldiers continued to use the types of helmet used by the army of the Republic since about 250 BC: the Montefortino-type and Coolus-type. From about 70 AD onwards, these were replaced by more sophisticated designs, the so-called "Imperial Italic" and "Imperial Gallic" types. The aim of these innovations was to increase protection, whilst not obstructing the soldier's senses and mobility.


title: Imperial Roman army

text: The "Imperial Gallic"- type which predominated from about AD 70 onwards, is a good illustration. The helmet features hinged cheek-guards covering the largest possible part of the face without restricting the soldier's breathing, sight and shouting-range. A horizontal ridge across the front of the bowl acted both as nose- (and face)-guard and as reinforcement against downward cuts on the bowl. Ear-guards protrude from the side of the helmet, but do not obstruct hearing. A shallow neck-guard was angled to the bowl to prevent chafing against the metal cuirass.


title: Imperial Roman army

text: The legionary "scutum" (plural form: "scuta"; derivation: It. "scudo", Sp. "escudo", Fr. "écu"; Rom. "scut"), a convex rectangular shield, appeared for the first time in the Augustan era, replacing the oval shield of the army of the Republic. Shields, from examples found at Dura and Nydam, were of vertical plank construction, the planks glued, and faced inside and out with painted leather. The edges of the shield were bound with stitched rawhide, which shrank as it dried improving structural cohesion. It was also lighter than the edging of copper alloy used in earlier Roman shields.


title: Imperial Roman army

text: The "scutum" disappeared during the 3rd century. All troops adopted the auxiliary oval (or sometimes round) shield ("clipeus").


title: Imperial Roman army

text: The "gladius hispaniensis" (adopted by the Romans from an Iberian design, probably during the First Punic War (260-41 BC), was a short (median length: 450 mm) stabbing-sword that was designed for close-quarters fighting. It was standard for the Principate infantry (both legionary and auxiliary). The cavalry used the "spatha" (It. "spada", French "épée", Sp. "espada", Rom. "spada"), a longer (median length: 760 mm) sword that allowed longer reach and easier swing.


title: Imperial Roman army

text: Legionaries were equipped with the developed version of the "pilum", a heavy javelin (throwing-spear) that had been used by Roman soldiers since around 250 BC. This weapon had lead counterweights to assist stability in flight and penetration; a barbed point to prevent withdrawal from flesh or shield; and a buckling shank to prevent it being thrown back. During the Republic, legionaries had been equipped with two of these, but now appear to have carried only one. Modern tests have shown the effective range of these javelins to be about 15 m. It appears that auxiliaries were not equipped with a "pilum", but with a light spear.


title: Imperial Roman army

text: Archers of the imperial army were equipped with the recurved composite bow as their standard. This was a sophisticated, compact and powerful weapon, suitable for mounted and foot archers alike (the cavalry version being more compact than the infantry's).


title: Imperial Roman army

text: In the 1st and 2nd centuries, a Roman soldier's clothes consisted of a single-piece, short-sleeved tunic whose hem reached the knees and special hob-nailed sandals ("caligae"). This attire, which left the arms and legs bare, had evolved in a Mediterranean climate and was not suitable for northern Europe in cold weather. In northern Europe, long-sleeved tunics, trousers ("bracae"), socks (worn inside the "caligae") and laced boots were commonly worn in winter from the 1st century. During the 3rd century, these items of clothing became much more widespread, apparently common in Mediterranean provinces also. However, it is likely that in warmer weather, trousers were dispensed with and "caligae" worn instead of socks and boots.


title: Imperial Roman army

text: Under Augustus, the European borders of the empire he inherited from his grand-uncle Julius Caesar were considerably expanded. During the first half of his sole rule (27 BC – 14 AD), Augustus' central strategic objective was to advance the Roman border from Illyricum and Macedonia to the line of the Danube, Europe's greatest river, in order both to increase strategic depth between the border and Italy and to provide a major fluvial supply route for the Roman armies in the region. The strategy was successfully executed: Moesia (29–7 BC), Noricum (16 BC), Raetia (15 BC) and Pannonia (12–9 BC) were annexed in steady succession. After settling the Danube border, Augustus turned his attention to the North, where Julius Caesar had in 51 BC established the border of Roman Gaul along the river Rhine, the second major European fluvial route. Augustus launched an ambitious strategy of advancing the Rhine border to the river Elbe, aiming to incorporate all the warlike Germanic tribes. This would eliminate their chronic threat to Gaul, increase strategic depth between free Germans and Gaul, and make the western Germans' formidable manpower available to the Roman army. But a massive and sustained military effort (6 BC – AD 9) came to nothing. Roman advances in Germania Magna (i.e., Germany outside the empire) had to be scaled down during the Great Illyrian Revolt of AD 6–9, when many troops were diverted to Illyricum. Then Augustus' expansion strategy suffered a crushing setback when some 20,000 Roman troops were ambushed and massacred by the Germans at the Battle of the Teutoburg Forest in AD 9. After this, Augustus shelved his Elbe strategy. It was apparently revived briefly by his successor Tiberius, whose nephews, the generals Germanicus and Drusus, launched major and successful operations in Germania in AD 14–17, during which the main tribes responsible for Varus' defeat were crushed and the three lost legionary "aquilae" (eagle-standards) were recovered.


title: Imperial Roman army

text: If Tiberius ever contemplated advancing the border to the Elbe, by AD 16 he had clearly abandoned the idea and decided to keep the border at the Rhine. Most likely, he assessed the Germanic tribes as too powerful and rebellious to incorporate successfully into the empire. After this, plans to annex western Germania were never seriously revived by Augustus' successors. Under the Flavian emperors (69–96), the Romans annexed the trans-Rhenane region they called the Agri Decumates, i.e., roughly the territory of the modern southwestern German state of Baden-Württemberg. But this acquisition was strictly aimed at shortening the lines of communication between the legionary bases of Germania Superior and Raetia provinces (Mainz and Strasbourg in Germania Superior and Augst and Regensburg in Raetia), by incorporating the salient between the upper reaches of the Rhine and Danube rivers. It was not part of a renewed effort to subdue Germany as far as the Elbe.


title: Imperial Roman army

text: Doubtless mindful of the costly failure of his Elbe strategy, Augustus reportedly included a clause in his will advising his successors not to attempt to expand the empire further. In the main, this advice was followed, and few major permanent annexations were made for the duration of the Principate. The main exceptions were (a) Britain, which was invaded by the emperor Claudius in AD 43 and was progressively subdued (as far as the Tyne-Solway, line of the later Hadrian's Wall) in 43–78. However, the stiff, prolonged resistance offered by native tribes seemingly confirmed Augustus' warning, and reportedly led the emperor Nero at one stage to seriously consider withdrawing from Britain altogether; and (b) Dacia, conquered by Trajan in 101–6. In both cases, it appears that, apart from the emperors' self-glorification, the primary motivations were probably the target-countries' mineral resources and also to prevent those countries becoming bases for anti-Roman resistance in Gaul and Moesia respectively.


title: Imperial Roman army

text: Apart from Britain and Dacia, other major territorial acquisitions by ambitious emperors were swiftly abandoned by their immediate successors, who took a more realistic view of the value and defensibility of the new possessions:


title: Imperial Roman army

text: The Rhine-Danube line thus remained the permanent border of the Empire in Europe for most of the Principate, with the exceptions of the Agri Decumates and Dacia. (Even these two salients were given up in the late 3rd century: the Agri Decumates were evacuated in the 260s and Dacia by 275. It appears that the Romans had exhausted the recoverable mineral wealth of Dacia and that both salients had become too expensive to defend). In the East, despite a certain amount of see-sawing in the disputed buffer-zone of Armenia, the long-term border with the Parthian empire was settled along the upper Euphrates river and the Arabian desert. In North Africa, the Sahara desert provided a natural barrier. As the borders became settled, the Roman army gradually mutated from an army of conquest to one of strategic defence, with long-term, fortified bases for the legions and strings of auxiliary forts along the imperial borders. The strategy adopted to ensure border security and the role required of the army by that strategy is discussed in Border security strategy, below.


title: Imperial Roman army

text: In a different category are the Roman troops deployed to protect the Greek cities on the northern shores of the Black sea (Pontus Euxinus). These cities controlled trade in the vital resources of the northern Black sea region (principally grain from Sarmatia and metals from the Caucasus region). Pontic Olbia and the Roman client-states of the Bosporan kingdom and Colchis hosted Roman garrisons for much of the Principate era. But here the Romans relied on tame native monarchies rather than direct annexation. By this means, the Black sea was turned into a Roman "lake" inexpensively.


title: Imperial Roman army

text: According to Theodor Mommsen, the imperial Roman army relied on a "forward" or "preclusive" defence strategy, a view generally accepted by modern scholarship: cf. Edward Luttwak's "Grand Strategy of the Roman Army" (1977). Forward-defence aimed at neutralizing imminent barbarian incursions before they reached the imperial borders. This was achieved by stationing units (both legions and auxilia) on or near the border. Luttwak argued that annexations such as the Agri Decumates and Dacia were aimed at providing the Roman Army with "strategic salients", which could be used to attack enemy formations from more than one direction, although this has been doubted by some scholars. According to Luttwak, the Roman response to any threat would be a pincer movement into barbarian territory: large infantry and cavalry forces from the border bases would immediately cross the border to intercept the coalescing enemy army; simultaneously the enemy would be attacked in the rear by elite Roman cavalry ("alae") advancing from the strategic salient(s). In any event, forward-defence obviously required the army to maintain first-rate and timely intelligence of events in the barbarian borderlands, which was provided by a system of small forts and fortified watch-towers in the cross-border regions, and by continuous cross-border patrols and scouting-operations ("explorationes").