Roman Military Glossary

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Actuarius – Senior clerk’s deputy

Assisted the cornicularius with his duties in the tabularium, and was himself assisted perhaps by several librarii.

Aedes – Dwelling place of a God

The main chapel, in which legionary insignia, among others, was stored, located in the central part of principia, surrounding the courtyard. The main treasury (aerarium) was often located in its floor. In this chapel stood statues of gods and divine emperors, and altars on which sacrifices were made;

Ala(e) – ‘Wing(s)’

Auxiliary cavalry squadron(s) commanded by a praefectus and consisting nominally of either five-hundred or one-thousand horsemen. The name ala means ‘wing’ in Latin, and refers to their being used during battle deployed on the flanks of an army. In a second-century census of the Roman military, the alae quingenariae outnumbered the alae millariae by ninety units to ten. A single cavalry ala would be subdivided into several turmae, which likely varied in size depending on the size of the parent unit.

Ala Quingenaria – ‘Five-hundred strong wing’

A squadron of auxiliary cavalry containing a nominal 500 horsemen, subdivided into 16 turmae. The number of cavalrymen in each troop is generally believed to be 32, though this figure is not proven. Each turma was commanded by a decurio, who was certainly not to be numbered among the ordinary cavalrymen, though it is uncertain whether his junior officers, Arrian’s duplicarius and sesquiplicarius should be included. If we settle for a troop strength of 32 and include the sub-officers in this figure, the quingenary auxiliary cavalry cohort would contain 512 troopers, 16 decurions and a prefect.

Ala Milliaria – ‘One-thousand strong wing’

A squadron of auxiliary cavalry containing a nominal 1,000 horsemen, though the actual figure is almost certainly less. This unit is known to have consisted of 24 turmae, each commanded by a decurio, but the actual number of cavalrymen in each troop is uncertain. If there were 32 troopers per turma, which is thought to be the case in the smaller alae quingenariae, the unit size would be only 768 troopers, rather small for a nominal ‘one-thousand strong wing’. It has been suggested – by Eric Birley – that the turmae in a milliary cavalry unit each had 42 men, which gives 1,008 troopers per unit. As in the smaller cavalry unit, the decurio was not numbered among the ordinary troopers, and would be in addition to whatever troop-size proves to be correct. Given our current knowledge, the milliary auxiliary cavalry cohort contained anything between 768 to 1,008 troopers plus 24 decurions and the praefectus alae.
I am inclined towards a figure of 40 men per milliary troop, based on the premise that an extra contubernium of eight men were simply added to the four already thought to exist in a quingenary unit, which would increase the troop strength from 32 to 40. If we then accept this figure of 40 troopers to each turma, the total strength of an ala milliaria including all it’s officers would be 985 men, which is closer to the mark. The only milliary cavalry fort excavated is that of Ala II Flavia pia fidelis at Heidenheim in Germany, which was the largest fort in the Roman province of Raetia. The floor-plans of the timber-built triple barrack-blocks uncovered in the retentura here, suggest that there were six contubernia per milliary troop, though the irregular plan of the rooms adjacent to the officers quarters at each end of the blocks perhaps indicate that these rooms formed part of the officer’s accommodation, and were not used to house ordinary troopers.


The man who carried the silver eagle (later gold eagle), the legion’s most important standard, was the aquilifer; consequently, he was also the most important of the legion’s standard bearers (signiferi). The loss of an eagle was not something to be tolerated; the legion was expected to fight until its own destruction rather than surrender it.

Armamentarium – Armoury/Arsenal

Weapons stores containing ballistae and bolts, onagri and slingshot, caches of gladii and pilae and other items of weaponry. They were sometimes built in long ranges along both sides of the courtyard in the principia, and in other forts they have been identified as separate buildings within the latera praetorii. The armamentaria were often subdivided into several rooms with access from the courtyard of the principia, in these cases it is probable that one or more of the rooms were used by the custos armorum or even a curator operis armamentarii.

Armilustrium – ‘Purification of the Armaments’

A military festival held annually on October 19-20th to celebrate the conclusion of the campaign season, during which captured arms were dedicated to Mars, and the standards purified.

Ascensi – Staircases

These gave access to the rampart walk on the vallum (ascensi valli) from the interior of the fort or intervallum, notably in the immediate area of the gates, though usually found at regular intervals around the defences. Unless in a temporary tactical encampment where they were of turf, ascensi were usually of wooden construction, sometimes with stone foundations and at other times entirely of stone, especially if the defences themselves were of stone.

Auguratorium – ‘Place of Augury’

In the camp of Hyginus this was an area in the latera praetorii where religious sacrifices were made and the auspices taken. In the later forts, they were probably incorporated within the cross-hall of the principia.



Ballistarius (plural ballistarii) were infantrymen of the Roman army who handled ballistae. They were classed as immunes, exempt from fatigue duty of entrenching or building.


The ballista, plural ballistae, sometimes called bolt thrower, was an ancient missile weapon that launched either bolts or stones at a distant target.


Campestres – The Goddesses of the Parade Ground

These deities were revered by cavalry troopers rather than infantry soldiers, and in some instances may have been honoured with shrines erected on or beside the campus, such as at Benwell (Condercum)(RIB1988).

Campus – Parade Ground

Beside each auxiliary fort there was an open area of ground, cleared of vegetation and often topped with gravel, on which weapon training and military drill would be practiced.

Cardo Decumanus – Dorsal Axis

The longer of the two principal axes upon which a Roman fort was laid out, crossed at right-angles in the centre of the camp by the cardo maximus, and providing the line of both the via praetoria at the front and via decumana at the rear of the camp.

Cardo maximus – Lateral Axis

The shorter of the two principal axes of a Roman fortification which provided the line of the via principalis in the completed camp, the centre of which was termed the groma and was crossed at right angles by the cardo maximus.

Carnarium – Provision Rack

Described by several classical authors usually in a culinary context, a carnarium was a framework with hooks upon which provisions could be hung, particularly joints of meat. It is possible that carnaria of some description were utilised by the Roman military to store provisions in the roof-spaces of the horrea, above the grain bins.

Cella – Storehouse

in its primary sense, means a store-room of any kind. Of these there were various descriptions, which took their distinguishing denominations from the articles they contained, as, for instance:

  • the cella penuaria or penaria, where all kinds of provisions (penus) were stored, especially those of which a stock was laid in for a long time,
  • the cella promptuaria, promptuarium, or promum, the larder, where meat and other things required for immediate consumption were kept
  • the cella olearia,  the magazine of an olive-yard in which the oil was stored
  • and cella vinaria, store-room of a vineyard, in which the new wine was kept in dolia or cupae, while older wine was put into amphorae and matured in the apotheca.

Centuria – ‘Company of One-hundred Men’ / Century

A primary unit of manpower in a legion; there were six centuries in each legionary cohort, and ten cohorts per legion, therefore, sixty centuries per legion. In antiquity the count of men in each century was exactly one-hundred, which was in late republican times reduced to eighty men and subdivided into ten contubernii of eight men each. The centuriae in the first cohort of an imperial Roman legion were of double strength, each numbering one-hundred and sixty legionaries.

In the marching camp of Hyginus each legionary century was housed in eight leather tents or papiliones, which were pitched in a straight line (hemistrigium) with the centurion’s larger tent at the end nearest to the vallum. Each tent would house a contubernium of eight men, the remaining sixteen men from each century which were currently posted on guard duty would not require accomodation; the tents in a Hyginian camp were used, therefore, on a rota-basis. The eight papiliones per century of the Hyginian marching camp would be translated in a permanent fort into ten contubernia.

Centurio – Century Commander / Centurion

The officer in charge of an individual centuria. He was assisted by his subordinate officers; the signifer, the optio and the tesserarius. All these officers would be housed in separate quarters at the end of each barrack-block, in comparative luxury to the common legionaries. In the Roman legions – also in the auxilia – there were different grades within the rank of centurion, which also determined which century within the cohort the centurion would command:

Table of Ranks of Legionary Centurions

CenturyFirst CohortOther Cohorts
1stprimus piluspilus prior
2ndprincepspilus posterior
3rdhastatusprinceps prior
4thprinceps posteriorprinceps posterior
5thhastatus posteriorhastatus prior
6th hastatus posterior

Cippi – Obstacle Trenches

These were long pits or fossae, 5 feet deep, perhaps with a W-like profile, inside which were fixed obstacles of sharpened tree branches; they are described by Caesar (De Bello Gallico, VII.73-80).

Clavicula – ‘Steering Obstacles

These are extensions to the vallum of a camp in the area of the portae, forming a defended passageway which permitted egress to the camp by an enemy only from his right, thus exposing the unshielded sword-arm to the defenders on the rampart on approach. There are two types; the external clavicula was an extension of the right-hand rampart, angled obliquely outwards then in front of the gateway, whilst the internal clavicula was an extension of the left-hand rampart which curved inwards behind the gateway.

Contubernium –

¹ eight man tent-section The smallest unit into which a legionary force was divided, comprising eight soldiers, all of whom shared a papilio on campaign, or a contubernia in garrison. These men would eat, sleep, drill and march together, fight the enemy side by side, go on duty at the same time, share their ablutions, and also spend much of their off-duty moments in each-others company. It is apparent from a pottery graffito found in the Neronian fortress at Burrium (Usk) Legionary Fort, that each contubernium had a leader appointed from among its members – probably based on the length of military service – who was presumably responsible for the general conduct of the men in his tent-section, and would also ensure that the rooms allocated for their use in the barrack-block were kept in order.

² section quarters There were ten contubernia to each barrack-block in a legionary fortress or auxiliary infantry fort, each holding an eight-man tent section or contubernium. They were divided into two areas; the forward area or arma where personal equipment and weapons would be stored, and a rear area or papilio where bunks were installed, meals were prepared, board games were played, and the men generally lived when off duty; the entrance to the section quarters was usually through a covered portico running along the length of the barrack-block. In the auxiliary cavalry forts there were eight contubernia to each barrack-block, where it appears that the troopers from two turmae were housed together. The contubernia in cavalry barracks were appreciably larger than those of the infantry units, as befitting their enhanced status.

Cornicularius – Senior Clerk

Chief official in charge of the administrative paperwork in the tabularium, assisted by the actuarius and perhaps several librarii.

Custos Armorum – Armourer

Literally ‘Keeper of the Armaments’, was the official entrusted with the keys to the armamentarium, drawn from among the most experienced centurions, he ranked very high in the administrative hierarchy of a Roman military encampment.



Decurion –

Decurion (Latin: decurio, plural decuriones) was a Roman cavalry officer in command of a squadron (turma) of cavalrymen in the Roman army. (Polybius VI.25)


Equites – Knight

The equites constituted the second of the property-based classes of ancient Rome, ranking below the senatorial class. A member of the equestrian order was known as an eques.

Evocatus – “Those called forth or the summoned”

An evocatus (plural evocati) was a soldier in the Ancient Roman army who had served out his time and obtained an honourable discharge (honesta missio) but had voluntarily enlisted again at the invitation of the consul or other commander. (Cassius, Dio. Roman History. 45.12)


Fabrica – Workshop

A Roman legion held within its ranks a formidable array of artisans, whose skills excused them from normal duties, they were thus termed immunes. Vegetius lists several skills – ‘engineers, carpenters, masons, wagon-makers, blacksmiths, painters and other artificers’ (epitoma rei militaris, II.11) – all of which would have been employed in the fabrica of a legionary camp under the command of a praefectus fabrum, the probable auxiliary equivalent for this post being the optio fabricae. Many buildings containing iron-smelting furnaces, large water cisterns and hypocausti have been identified as fabricae. They have been found in many of the legionary fortresses throughout the Roman empire, but few have been positively identified in auxiliary forts. It is probable that the workshop in an auxiliary fort was used maintenance rather than production, thus the heavier industries such as iron smelting, which would help to identify the site of the auxiliary fabrica would not be present, giving the false impression there were none. Hyginus places the fabrica in the praetentura, as far away from the valetudinarium as possible, so as not to disturb the sick soldiers, however, a large workshop has been identified in the retentura of the legionary fortress at Inchtuthil, where almost one-million iron nails had been buried, and there seem to be no hard rules for placement of the fabrica in practice.

Feriale Duranum – Timetable of Festivals

A list of military religious festivals which were observed by every unit in the Roman army. The list includes the festivals of the cultus signorum, the Rosaliae Signorum and the festival of natis signorum, all of which honour the regimental standards.

Fossae – Ditches

Although the typical Roman military ditch had a regular V-like profile, termed by Hyginus a fossa fastigata, there were other types of ditch employed. Ditches with a W-like profile may either be of the cippus type, or represent subsequent recuttings of a normal V-profile ditch on a slightly different line. The fossa punica is another well-known variant. In the marching camp of Vegetius the single ditch was a regulatory 5 feet wide and 3 feet deep, but auxiliary forts and legionary fortresses could have any number of ditches, depending on the local topography; all had at least one, many had two, and several had more, sometimes varying in number on different sides of the camp. The average dimensions for individual fossae of auxiliary forts ranged from 7 to 20-odd feet in width and between 4 to 10 feet deep. The actual width of the surrounding defensive system, however many individual ditches it contained, was obviously limited by the effective range of the garrison’s weapons hurled from the vallum.

Fossa Fastigata – ‘Slope-sided Ditch’

The classic V-profile ditch used by the Roman Military in their fortifications, is often found with a narrow slot in the bottom, variously interpreted as either an ‘ankle-breaker’ or as an aid to ditch drainage, probably a design feature, but possibly due simply to frequent clearance with a standard square-edged excavation tool.

Fossa Punica – ‘Punic Ditch’

This was a popular variation of the regular V-profile fossa fastigata, which, if present, was usually placed outermost in any ditch system surrounding a permanent fort or legionary fortress. This type of ditch had an irregular profile, the innermost slope closest to the vallum was quite shallow while the outer slope was almost vertical. This design has been interpreted as a type of ‘man-trap’; anyone foolish enough to venture inside its perimeter would be forced to turn his back in order to climb the steep outer-wall, thus exposing himself to the defenders on the ramparts as an easy javelin target. It is probable that the shallow inner slope was merely to enable the bottom of the ditch to be seen from the rampart, but may also have served to lure any attackers into the ‘killing zone’ by the seemingly easy appearance of its inner slope.


Groma –

¹ survey tool A groma was the singular most important instrument of the mensores, or Roman military surveyors, and their commander the praefectus castrorum. The groma was used to mark-out the two main axes of the camp; the cardo decumanus which pointed in the direction from which the main danger would arise, and the cardo maximus which lay at right-angles to it. The groma consisted of a cruciform metal frame, set at meticulous right angles, with plumb-lines suspended from the extremities of each arm. The instrument was suspended from a tall staff set slightly off-centre, which would allow the surveyor to make sightings along the plumb-lines unimpeded by the pole itself. The main axes of the camp would then be measured by the mensores – using accurately cut poles perhaps ten feet in length – and marked-out using coloured flags, along the line indicated by the groma.

² focus of the camp The word groma is also thought to name the point where the two main streets crossed before the entrance to the headquarters building – where the like-named surveying instrument was initially placed. There has been evidence of small, temporary altars erected at this position at several forts, particularly in Germany, and it is thought that these altars were used during a religious ceremony conducted by the commander of the regiment, which conferred the blessing of the martial gods upon the camp itself.

Gyrus – Training Ring / Animal Corral

Also identified as a vivarium, the only known example of an auxiliary fort containing a purpose-built gyrus/vivarium throughout the whole of the Roman empire is ‘The Lunt’ fort at Lunt (Baginton) Roman Fort near Coventry. The structure was formed from fifty semi-circular cut timbers set upright in a circular trench, probably supporting a framework of cross-timbers. A single entrance passage adjoined the structure on the north-east, which had gates at both ends, presumably to control the animals entering or leaving the main structure. It is probable that both horses and men were trained within the gyrus, the instructor most likely remained in the centre of the ring, while the trainee was walked around the perimeter on the end of a leash.


Horrea – Granaries

The staple diet of the Roman army was corn, and great care was taken to ensure that the grain-supply was secure – soldiers tend to mutiny if they are not fed. The granaries in an auxiliary fort were generally placed in the latera praetoria beside the principia, though in the legionary fortress at Inchtuthil Roman Fortress the granaries were arranged beside the barrack-blocks of each cohort, in the retentura and praetentura. The floors of the granaries were raised off the ground by various means, to allow the free circulation of air around the building and thus to reduce humidity, which would cause the stored grain to spoil. The walls of the buildings were heavily buttressed, to compensate for the lateral pressure exerted by the ‘semi-fluid’ grain. The interior was protected from intrusion by insects and rodents with amurca, the residue left over from the processing of olives, which was pasted into any cracks in the walls and floor, and also mixed into the plaster used to seal the room. The floors of the granaries were taken up by large wooden storage bins to hold the corn, perhaps with carnaria in the roof-spaces from which to hang more provisions. In some timber-built forts, for example the antonine fort at Bearsden Roman Fort, the granaries are the only buildings built of stone, which underlines how important these buildings were to the Roman military.


Immunes – ‘The Exempt’

These were men who were excused the routine tasks such as ditch-digging and patrolling the ramparts because they possessed some specialised skill or trade which qualified them for special duties. Vegetius lists several skills which would qualify a soldier among the immunes; ‘engineers, carpenters, masons, wagon-makers, blacksmiths, painters and other artificers’. Other trades included farriers, surveyors, shipwrights, glaziers, fletchers, armourers, hunters, butchers, grooms, plumbers, bronze-smiths, lime and charcoal burners, and keepers of sacrificial animals. Many of these technical specialists were employed in the buildings of the latera praetorii of the camp, primarily the valetudinarium, the veterinarium, and especially the fabrica. It is very likely that these men were seconded to other units on a temporary basis when required.


Another of the signiferi, introduced after the formation of Roman empire, this man bore an image of the emperor to remind the legionaries of their oaths and where their loyalties lay. The post was first established during the reign of Augustus.

Intervallum – ‘Within the Ramparts’

Polybius records that a 200 foot wide gap should be left between the ramparts and the tents, forming an annular space all around the camp, this was known as the intervallum; Hyginus reduces this to only 60 feet. The purpose of this gap was to allow the soldiers unhindered access to the ascensi leading to the vallum itself, and also to ensure that burning missiles hurled into the camp interior should fall short of any buildings. A road named the via sagularis ran through the intervallum around the entire camp perimeter. The barrack-blocks within many Roman camps were built with the centurion’s quarters closest to the intervallum, so that the officers could quickly answer any call to arms and coordinate the manning of the ramparts. In many forts the camp ovens were placed in the intervallum, either embedded into the rear of the rampart, or in covered cook-houses. Rainwater was directed away from the centre of the camp along covered drainage channels, into culverts running along the edges of the intervallum, along which the rainwater was ultimately diverted into the fort ditch. In many forts the ablutions were situated in the lowest part of the intervallum, adjacent to the rampart, where the water draining from the camp interior would be used to flush the latrines, a prime example in Britain being Housesteads (Vercovicivm) on Hadrian’s Wall.

Latera Praetorii – ‘Beside the Praetorium’

This was the central range of the camp, separated from the praetentura at the front of the fort by the via principalis, and from the retentura at the rear of the camp by the via quintana. The main buildings of the camp were built in the latera praetorii; the principia or headquarters building was almost always located at the physical centre of the fort in this area, surrounded to the rear and sides by the praetorium (commanding officer’s house), the horrea (granaries), the valetudinarium and veterinarium for sick men and animals, and in some forts a fabrica (workshop).

Legatus Legionis  – Legate

The men who filled the office of Legate were drawn from among the senatorial class of Rome. There were two main positions; the legatus legionis was an ex-praetor and the man in command of one of Romes elite legions, while the legatus pro-praetore was an ex-consular, who was given the governorship of a Roman province with the magisterial powers of a praetor, which in the case of Britain gave him overall command of up to four legions.

Liberarii – Office Clerks

Assisted the cornicularius with his duties in the tabularium.

Lilia – ‘Lilies’

These obstacles were described by Caesar (G.W. VII.73), and consisted of a three foot deep pit with tapering sides, at the bottom of which a sharpened stake was fixed upright and concealed with brushwood and leaves. These man-traps were named ‘lilies’ because of their resemblance to that flower, and were generally deployed in a quincunx pattern.

Papilio(nes) – Military Tent(s)

Made of sewn leather sections and measuring 10 x 10 Roman feet, they housed a contubernium of eight legionaries when on campaign. The eight tents allocated to each centuria were pitched close together in a straight line (hemistrigium) with the centurion’s tent at the end of the line closest to the vallum. Arms and equipment were stored in the areas immediately before each tent, and the baggage animals tethered in the spaces between each centuriae, which were, according to Hyginus, erected facing each-other in pairs.


Portae – Gates

In a classical Roman encampment there were six gates; the porta praetoria at the front of the camp, the porta decumana at the rear, the two portae principales, one at each end of the via principalis, and the portae quintanae at each end of the via quintana; in many forts some of these gates would be omitted, particulaly the portae quintanae. The gateways of the camp were generally built out of the same materials as the vallum, and the methods used in their construction are discussed in the Roman Military Camps..

Porta Decumana – Rear Gate

It was from this gate that soldiers convicted of serious crimes, such as desertion, were led out from the camp to be executed, likely by being stoned to death.

Porta Praetoria – ‘Praetorian Gate’

This gate lay at the opposite end of the via praetoria from the principia in the centre of the camp – in republican times called the praetorium. According to both Hyginus and Vegetius, the porta praetoria should lie closest to the enemy.

Portae Principales – ‘Principal Gates’

These gates lay at either end of the via principalis, which ran in front of the principia and the praetorium in the center of the camp.

Portae Quintanae – Side Gates

These portals lay at either end of the via quintana in the rear portion of the camp. They were often omitted, their positions in the ramparts frequently being taken by interval towers instead.

Praefectus Alae – ‘Prefect of the Wing’

This was the commander of one of Rome’s cavalry units, the auxiliary elite, and was the highest military rank normally achievable by the Roman equestrian class, the Knights of Rome. The prefect of an ala milliaria ranked above all other auxiliary commanders.

Praefectus Annonae – ‘Commissioner of the Grain Supply [of Rome]’

Another name for the curator annonae, a position initially offered to Pompey by the Roman senate to counter the famine of 57BC, and offered as a honorary title to Augustus in 22BC. Augustus had in 29BC decreed that the post of praefectus annonae be filled from among the equestrian order.

Praefectus Castrorum‘Prefect of the Camp’

Sometimes known as the praefectus legionis this rank was the third-in-command of a legion, recruited from among its senior centurions, and was the highest rank achieveable by the Roman plebian class. The men who served in this position had spent their entire lives in the army, working their way up through the ranks, and were granted equestrian status on completion of their term of service. The praefectus castrorum was concerned with all the stages of construction of the Roman military camp, and usually responsible for choosing the site, though we are told by Tacitus that the legate Julius Agricola preferred to explore and choose the site himself. His other duties included directing the entrenchments, inspecting the lines of tents in the temporary camp and supervising the construction of barrack-blocks and internal buildings in permanent forts, sinking wells and building aqueducts, and ensuring the supply of saws, entrenching tools, turf-cutters and all the instruments of the military engineer. He was also responsible for the furnishings in the interior buildings, the supply of wood, iron and coal to the fabrica, and the medical supplies used in the valetudinarium.

Praefectus Cohortis – Cohort Commander

These were lower ranking prefects, in charge of the least prestigious auxiliary units the cohors quingenaria peditata (‘cohort of five-hundred foot [soldiers]’), or the cohors quingenaria equitata (‘cohort of five-hundred [soldiers] with horse’) were both commanded by a praefectus.

Praefectus Praetorio – ‘Praetorian Prefect’

This rank represented the epitome of equestrian power, being the man in charge of the Praetorian Guard stationed outside Rome itself.

Praefectus Urbi – ‘Prefect of the City’

This was a consular post, ‘the highest dignity of the senate’ (Dio lxxix.14.2), who was in command of the City of Rome whenever the two consuls were not present. His jurisdiction extended to the countryside surrounding Rome for a distance of one hundred miles. The appointment of Adventus to the position by emperor Macrinus in 217 caused considerable dissent among the senate because he had not yet served as consul, a condition fulfilled since the time of Augustus. We are told (Dio liii.33.3) that in 23BC at least, two Prefects of the City presided over each day of the Feriae Latinae, and that one of them had not yet attained adulthood. Earlier references record that during the republic, there were several urban prefects in office at the same time, and it is also known that Claudius appointed his sons-in-law Pompeius and Silanus to the position to preside over the Latin Games of 41AD.

Praefectus Vigilum – ‘Commander of the Night Watch’

Augustus decreed in 29BC that the posts of praefectus vigilum and praefectus annonae, both highly prestigious offices in Rome, be filled from among the equestrian order.

Praetentura – ‘Forward Extent’

This was the front part of the camp, between the via principalis and the porta praetoria, and bisected by the via praetoria. This area was generally filled with the tents or barrack-blocks of the garrison, the first cohort of a legion being always housed here. In the camp described by Hyginus, this area also contained the valetudinarium and veterinarium, the tribunes’ houses, the scholae of the officers, and the fabrica; most of these building being transferred to the latera praetorii in the auxiliary forts.

Praetorium –

¹ General’s Tent In the temporary marching camps described by Polybius and Hyginus the praetorium is the area reserved in the centre of the camp for the tents of the legionary commander, before which the legionary eagles were grounded along with the standards of each century. In the Polybian camp it was flanked on one side by the quaestorium and on the other by the forum, with the tribune’s tents arranged in front of it along the via principalis. The Hyginian plan places the praetorium in the latera praetorii, with the auguratorium and the general’s tribunal, flanked along one side by the centuriae of the first cohort. The praetorium in temporary marching camps therefore comprised both the living accommodation of the unit commander and the administrative headquarters of the unit.

² Commander’s House In the permanent camps the praetorium of the unit commander was displaced from the centre of the camp and located in the latera praetorii, adjacent to the administrative offices of the garrison which were retained at the centre of the fort in the prinicipia. Whether it was a legion of highly-trained citizen troops or a numerus of auxiliary foot soldiers, the commander of one of Rome’s military units was a highly respected man, and a large area was set aside for his personal residence. The praetorium generally took up about a third of the area of the latera praetorii, or about ten percent of the entire space within the ramparts. This not only befitted his status in the military hierarchy, but was also required to accommodate his personal entourage of family members, friends, clients, advisors, lackeys and domestic slaves, and also in order to receive visitors. The praetorium was almost invariably based around a central courtyard, and is closely similar in layout to the traditional Roman domus. The building could contain the same luxury structural features as many of the wealthy town-houses, which included hypocaust heating systems, bath-suites, latrines, kitchens and stables. In some forts, for example Hod Hill (Dunum) Roman Fort, separate smaller praetoria have been identified, often in the praetentura, which may indicate a garrison comprised of several units.

Principia – Headquarters Building

The literal, administrative and religious centre of the later Roman forts, situated in the centre of the latera praetorii, fronting onto the via principalis and facing down the length of the via praetoria, the building was thus visible as soon as one entered the porta praetoria. The building consisted of three distinct parts; a collonaded courtyard, an isled cross-hall and a rear range of rooms. The collonaded courtyard was surfaced with gravel or paved with stone, and may be fronted by a portico or even a separate entrance hall spanning the via principalis, the side ranges of this area may also contain armamentaria, scholae, or other store-rooms and offices. The cross-hall beyond the courtyard extended across the entire width of the building, and was usually the tallest structure in the interior of the camp, having celestory windows in rows, to provide light for the commander’s tribunal and auguratorium which it housed. Beyond the cross-hall was a rear range of rooms, usually five in number, the central room of which housed the regimental standards and treasury, and was named the sacellum, flanked on one side by the tabularium and on the other by the offices of the signiferi.


Quaestorium – ‘Aquisition Area’

Polybius places this section near the centre of his camp, adjacent to the commanding officer’s tents in the praetorium, on the opposite side from the forum. In the Hyginian model, the quaestorium was placed in the retentura at the rear of the camp between the praetorium and the porta decumanus. This area was where prisoners and booty were kept under guard, where supplies were organised and distributed, and also where the artillery and heavy baggage was stored. The area was under the direct supervision of the praefectus castrorum, the Prefect of the Camp, who was possibly also quartered here.


Retentura – ‘Holding Area’

This was the rearward portion in the tripartite camp of Hyginus, alongside the latera praetorii in the centre of the camp, and opposite the praetentura at the front, lying between the via quintana and the porta decumana. In a marching camp this area housed the tents of the least experienced troops, the quaestorium of the Camp Prefect and also the tents of any accompanying auxiliary brigades. The buildings found in the retentura of the permanent forts were mainly centuriae (barrack-blocks), stabuli (stables) and cellae (storehouses). The retentura was sometimes omitted in the smaller forts and fortlets, especially if no rear gate was provided. The Antonine fort at Newstead (Trimontium) Roman Fort in lowland Scotland had a wall erected across the width of the retentura parallel with the via quintana, which apparently was to separate two legionary cohorts stationed in the praetentura from a quingenary cavalry wing housed at the rear. There are several examples of bath-houses built within the retentura of auxiliary forts, especially in Germany.


Sacellum – Regimental Shrine

Regimental Shrine Located on the cardo decumanus close to the geometric centre of the camp, this building was visible through the portals of the principia at the terminus of the via praetoria as soon as one entered through the main gates. The importance the Romans placed on this building is backed-up by field-evidence, for in many modern excavations the sacellum has proved to be the only internal building constructed of stone, or at least, the first to be rebuilt in stone. Centrally located in the rear range of the principia, the sacellum was flanked on one side by the tabularium and on the other by the offices of the signiferi. The building often projected out from the rear of the building or was apisdal in plan. It housed the images of the emperor, the signa of the unit and the vexilla of its constituent companies, and the garrison’s altars, which were often dedicated ‘to the genius of the unit’. The sacellum also housed the regimental pay-chest which was placed directly on the floor in many of the the timber-built forts, or else located in a sunken strongroom beneath the floor of the shrine. The strongroom was lined in timber or stone and accessed either through a trapdoor in the ceiling from the sacellum above or along a stair-passageway often leading from the cross-hall of the principia, but in some instances from the offices of the signiferi next door. A guard was normally posted outside the sacellum, and was a honoured duty.

Scholae – Officer’s Clubs

Hyginus places the scholae in the praetentura or forward part of the camp, alongside the tents of the military tribunes and legionary legates. Evidence has been recovered from the legionary fortress at Lambaesis, which suggests that rooms opening out into either end of the cross-hall of the principia were used as scholae by the officers of the garrison. No comparable evidence of this activity has been recovered from any Roman auxiliary fort, but this does not preclude the existence of scholae within the auxilia. Considering the lack of evidence to the contrary, it is quite possible that scholae were provided with purpose-built offices in the principia of many auxiliary forts, most likely in the rooms surrounding the central courtyard or off the cross-hall. In the Agricolan fortress at Inchtuthil Roman Fortress, a collonaded courtyard building with ranges of rooms along three of its sides has been tentatively identified as the scholae. This building lies in the praetentura of the fortress and opens out onto the via praetoria just behind the row of tribunes houses, evidently following Hyginus’ pattern.

Signa – Standards

The standards of all Roman military units were held to be sacred, thus they were stored in the most holy of places within the fort’s defences, the sacellum, or military shrine in the rear range of the principia. The signa or regimental standards were housed alongside the vexilla or flags of the individual centuries or decuries of the garrison. There were at least two religious ceremonies which revered the standards themselves; the Rosaliae Signorum, where the standards were decorated with crowns of roses, before the entire garrison assembled in the courtyard of the principia, and the festival of the natalis signorum also, was held exclusively in their honour. Vegetius states that half of the emperor’s donatives to the soldiers were to be deposited ad signa or ‘with the standards’.

Signifer(i) – Standard bearer(s)

Vegetius states that the signiferi were directly responsible for the finances of the garrison. Their offices lay in the rear range of the principia, to one side of the sacellum which housed the actual treasury, and the signa themselves. They kept records of all financial transactions, receipts, and accounts, and were directly accountable for all the coinage in the regimental funds, which was held in small bags or baskets, and stored in the paychest under lock and key in the sacellum. They were also responsible for paying each soldier his salary, after taking deductions for his food, kit, retirement pension, burial fund contributions, etc..

Stabulum – Stable

stabulum originally meant a stable, and would also mean a hotel where one could stop in with one’s horse.


Tabularium – Records Office

This normally consisted of two rooms in the rear range of the prinicipia, to one side of the sacellum. It contained records of the day-to-day activities of the fort, such as duty rosters, service records, leave schedules, illness reports and records of promotions, decorations, transfers and secondment. The records were inscribed on a variety of media, depending on local availability; slate, wooden waxed tablets, written in ink on papyrus, etc. The tabularium was the office of the cornicularius, who was assisted in his administrative duties by his deputy the actuarius and a number of librarii.

Tertiata – ‘by Thirds’

Hyginus suggested that ratio between the long and short sides of an encampment should be 3:2, and by the Flavian period almost every new fort or fortress was built to this format, which gives the classic ‘playing card’ outline. The interior of the camp was also divided into thirds, the forward part which lay closest to the enemy was called the praetentura, the rearward section was named the retentura and the middle third was labelled the latera praetorii.


The tessarius was the guard commander. It was his job to circulate the tessara (a small tablet) holding the daily watchword.

Thermae – Baths

In ancient Rome, thermae and balneae were facilities for bathing. Thermae usually refers to the large imperial bath complexes, while balneae were smaller-scale facilities, public or private, that existed in great numbers throughout Rome.

Titulum – ‘Staggered Obstacle’

This was a short length of ditch with an inner bank built in front of a camp gateway to protect the gates from frontal assault. The gates of the Hyginian camp were protected by tituli which were roughly the same length as the corresponding gap in the vallum and placed at a distance of 60 feet in front. A modification of the titulum which allowed egress from one side only, was termed a clavicula.

Tolleno – Water-lifter

A device for lifting water from a well where the water table is high, consisting of a long pivoted pole with a bucket at one end and a counterweight at the other. The poet Martial used a tolleno to water his garden, and his description suggests it was similar in form and function to a shaduf or shadoof, used nowadays in Egypt and throughout the near eastern countries.

Tribunal – Judicial Platform

A tribunal is a raised platform from which a magistrate hears evidence and pronounces judgement. Within a Roman military camp, this was where the camp commander would stand to address his men, issue orders, hear complaints, conduct court-martial proceedings, also to perform the necessary military ceremonial and religious duties. In the Hyginian camp the commander’s tribunal was situated in the latera praetorii, in later camps it was housed at one end of the cross-hall of the principia, usually on the right-hand side as one enters, and facing towards the rear of the building. A tribunal was also the name given to any raised platform, sometimes hastily constructed from cut and stacked turves, from which a Roman general would deliver speeches or review troops on parade; tribunal mounds of this type have been found beside the parade-grounds at Hardknott, Maryport, South Shields and Tomen-y-Mur.


There were six military tribunes attached to each legion in post-Marian era: five narrow-stripe tribunes (tribunus angusticlavius) and one broad-stripe tribune (tribunus laticlavius), the latter serving as the legate’s second in command.

Turma(e) – Cavalry Troop(s)

An operational section of an auxiliary cavalry ala, commanded by a decurio, whose size may have depended in turn on the size of its parent wing. In an ala quingenaria the size of each turma was probably 32 troopers, besides the troop commander, but a troop size of 42 cavalrymen has been suggested for those turmae in an ala milliaria.


Valetudinarium – Hospital

The hospital in a Roman camp was placed by Hyginus in the praetentura alongside the Scholae and the veterinarium, though in many forts the valetudinarium occurs in the latera praetorii alongside the granaries and the principia in the centre of the camp. Hospitals were present in almost all legionary fortresses, but seldom provided in auxiliary forts, notable exceptions in Britain being Housesteads (Vercovicivm) and Wallsend (Segedunum), both on Hadrian’s Wall. The hospital administration was under the control of an optio valetudinarii, though the actual medical practice was under the charge of a Chief Medical Officer or medicus ordinarius, both of which appear to be equal in rank to a centurion. The hospital was manned by a number of medical orderlies bearing the title miles medicus, who were presumably under the direct command of the administrator, and responsible for the day-to-day running of the hospital. The dressing of wounds was carried out by capsarii, similar in rank to the orderlies though commanded by the Chief Medical Officer. The soldiers who worked in the hospital were numbered among the immunes, men who were excused normal duties in order to work in specialized jobs. The valetudinarium building has a fairly distinct profile in legionary fortresses, in the form of an open courtyard, surrounded on all sides by a double row of individual cubiculae, separated by an ambulatory corridor illuminated through celestory windows. The layouts of hospitals in auxiliary forts is more varied, with the central courtyard design often featured, though scaled down, perhaps with a single row of cubiculae surrounding a small courtyard, separated by an ambulatory or peristyle; the hospitals in the forts on Hadrian’s Wall are of this type. Another form often seen in the smaller forts is that of a rectangular building with two rows of cubicles separated by a central corridor running along its main axis, such as at Corbridge (Corstopitum).

Vallum –

¹ rampart A Roman encampment was always enclosed by a defensive system comprising at least three components; a ditch or fosse, an inner bank or agger containing the ditch outcast, and a palisade or vallum surmounting the bank; the rampart then, contained both the agger and vallum elements. In the Polybian camp, the vallum is described as a linear mound of earth and turf surmounted by a palisade of wooden stakes. Hyginus says that it should be built of earth, turf or stone, eight Roman feet wide and six feet high. The method of construction varied greatly, depending on the size of the unit, the local military situation, and most importantly, the locally available resources. In temporary marching camps the rampart would be simply constructed using the Polybian method, whereas the ramparts of auxiliary forts, campaign forts and legionary fortresses were built using an astonishing variety of methods. Many auxiliary forts were built using the ‘turf and earth’ method, where the turves cut from the areas above the fossae were stacked up into two rows, with the space between being filled with the outcast from the ditches; on top of this basic agger foundation, the defensive structures forming the vallum were then added. The various methods of rampart construction are discussed in the Roman Military Camps.

² defensive system The Antonine Itinerary uses the word vallum to denote the massive frontier defences of Hadrian’s Wall across the north of England; in this context the word should more properly be translated as ‘fortifications’ or ‘defensive system’. Hadrian’s frontier system consisted of several component, one part of which is nowadays known as ‘The Vallum’. This massive structure was built behind the line of the Wall, and followed along its course for almost its entire length; the function it served is unknown.

Veterinarium – Animal Station

In the Roman camp of Hyginus, this building was placed in the praetentura next to the valetudinarium for sick soldiers. The word veterinarium is often interpreted as ‘horse hospital’, though a better translation may be ‘baggage animal park’. This building or area housed the pack animals, mules and oxen, the cavalry mounts, the sacred chickens meant for sacrifice in the principia, in fact every type of animal which the Romans required to run their military machine, and was not only for sick horses. The men working in the veterinarium were known as veterinarii and classed among the immunes who were excused normal duties. The single tombstone of a Hippiatros or ‘Horse Doctor’ serving in a cohors equitata, proves that such a rank existed, though it cannot be said from this lone evidence that every mixed cavalry cohort had one in attendance, or even that the elite cavalry squadrons posessed them.

Viae – Roads

A Roman military encampment was possessed of many roads, set out in a precise pattern, all of which served a specific function:

Via Decumana – ‘Way of the Tenth’

This road lay along the camp’s major axis, on the same line as the via praetoria. It ran from behind the Principia at the centre of the camp, at right-angles away from the mid-point of the via quintana, and passed out through the porta decumana at the rear, bisecting the retentura. The road was so named because it separated the Tenth Cohort from the Ninth in the legionary encampment. In the camp described by Hyginus this road was sixty feet wide.

Via Praetoria – ‘The Praetorian Way’

This road branched off at right-angles from the centre of the via principalis immediately before the entrance to the principia, and bisected the praetentura along the line of the cardo decumanus. The point at which this road pierced the fort’s defences marked the main entrance to the camp, unsurprisingly named the porta praetoria. The via praetoria was so named because in the legionary marching camp it led from the tent of the legionary commander to the front gateway; the commander of a Roman legion being an ex-praetor in rank. According to Hyginus, this road should be made sixty feet wide.

Via Principalis – ‘The Principal Way’

This street lay across the cardo maximus, the shorter axis of the camp, and passed in front of the principia in the centre of the fort. The via praetoria ran at right-angles from the groma marking the central point of the via principalis to the main gates of the fort, directly opposite the entrance to the principia. The via principalis generally continued through the defenses where gateways were maintained, the porta principalis sinistra and porta principalis dextra, to left and right of the principia. In the camp of Hyginus this road was sixty feet wide.

Via Quintana – ‘Way of the Fifth’

The via quintana was so called because in the legionary camp it separated the Fifth Cohort from the Sixth. Hyginus stipulates that it should be forty feet wide.

Via Sagularis – ‘Way of the Cloak’

This road is sometimes called the ‘intervallum road’ as it lay in the space between the rampart and the buildings in the interior of the fort, the intervallum. The via sagularis thus ran around the entire perimeter of the camp within the rampart, encircling the interior buildings. The etymology of its name seems to derive from the sagulum or small military cloak worn by the soldiers when on guard duty. The road may be so named because it ‘encloaks’ the interior of the camp in the same manner the sagulum encircles the shoulders, or possibly, because the soldiers were required to wear the sagulum when on patrol in the interior of the camp along this road.

Viae Vicinariae – ‘Local Ways’

Minor roads running between the barracks, stables, granaries and other buildings in the camp interior. In the legionary camp of Hyginus they were twenty Roman feet wide between the rows of tents.


See ‘gyrus’. above.