Dates in brackets give an approximate indication of period.
ala: (1) Term used under the Republic for the contingents of Italian allies, roughly equivalent in size to a Roman legion. The name meant ‘wing’ and derived from the standard formation of a consular army that placed two legions in the centre with an ala on either flank (late fourth to second century вс). (2) Term used for the cavalry units of the Imperial auxilia. These were either 512 or 768 strong and commanded by a prefect or tribune respectively (first to third century AD).
aquilifer: The standard-bearer who carried the legion’s standard (aquila), a silver, later gold, statuette of an eagle (first century вс to third century ad).
auctoritas: The informal reputation or prestige of a Roman politician which determined his influence in the Senate and was greatly added to by his military achievements (third to first century вс).
auxilia: Troops recruited from non-citizens, the auxilia of the Principate provided a valuable source of extra manpower for the Roman army, as well as the vast majority of its cavalry. They were not organized into legion-sized units, but into cohorts and alae (first to third century ad).
ballista: A two-armed, torsion catapult capable of firing bolts or stones with considerable accuracy. These were built in various sizes and most often used in sieges (third century вс to sixth century ad).
beneficiarius: A grade of junior officer usually recruited from experienced rankers who performed a range of policing and administrative roles often detached from their units (first to third century ad).
bucellarii: The household troops paid and supported by particular commanders, although nominally loyal to the emperor. The bucellarii were usually high-quality cavalry. The name derives from bucellatum, the army’s hard-tack biscuit, and emphasized the commander’s obligation to feed and provide for his men (fourth to sixth century ad).
Cantabrian ride: A drill practised by the Roman cavalry during which men rode in turn towards a target, wheeling to the right at short range and then riding parallel, keeping their shields towards the target. The object was to maintain a continual barrage of missiles at a single point in the enemy line, weakening an enemy before launching a charge sword in hand. Similar tactics were employed by cavalry, especially horse-archers, of many nations (first to sixth century ad).
cataphract: Close order, heavily armoured cavalrymen whose main tactic was the shock charge. Often the horses were also protected by armour. Their normal weapon was the two-handed lance, the contus, but some cataphracts carried bows as well. These troops were more common in the eastern empire, centurion: Important grade of officers in the Roman army for most of its history, centurions originally commanded a century of 60-80 men. Under the Principate many served for very long periods and provided an element of permanence in the otherwise short-term officer corps of the legion. The most senior centurion of a legion was the primus pilus, a post of enormous status held only for a single year (first century вс to third century ad).
century (centuria): The basic sub-unit of the Roman army, the century was commanded by a centurion and usually consisted of sixty, later eighty, men (late fourth century вс to third century ad).
cheiroballista: A version of the scorpion mounted on a mule-drawn cart to increase mobility (first century вс to sixth century ad).
clibanarius (clibanarii): A heavily armoured cavalryman, it is unclear whether or not these were identical to cataphracts, but it is possible that the term was applied to the heaviest troops. The name derived from a nickname meaning ‘bread-oven’, cohort (cobors): Originally the name given to the contingents which formed the Allied Alae under the Republic, the cohort became the basic tactical unit of the army by the end of the second century вс. It usually consisted of 480 men in six centuries, but there were also larger units of 800 in five or ten centuries (second century вс to third century ad). comes: Officers of the later Roman army, ranking below the magistri militum (late third to sixth century ad).
comitatenses: Units included in the regional forces not tied to specific frontier provinces (fourth to sixth century ad). consul: The year’s two consuls were the senior elected magistrates of the Roman Republic, and held command in important campaigns. Sometimes the Senate extended their power after their year of office, in which case they were known as proconsuls.
contubernium (contubernia): Term applied to the groups of eight men who shared a tent and messed together (third century вс to third century ad).
contus (or kontos): The long, two-handed thrusting spear employed by Parthian, Persian, Sarmatian, and later Roman cataphracts (first century вс to sixth century ad).
cornicularius: A grade of clerks included on the administrative staff of several officers in the legion (first to third century ad).
cuneus: (1) Term used for a formation intended to break through an enemy line by concentrating the moral and physical shock of a charge at a single point. It may have been triangular in shape or alternatively a deep, narrow-fronted column. (2) Term used for cavalry units of unknown size (third to fourth century ad).
decurion: Cavalry officer who originally commanded ten men. Under the Principate a decurion led a turma of about thirty horsemen (first to third century ad).
dictator: In times of extreme crisis a dictator was appointed for a six-month period during which he exercised supreme civil and military power. Later victors in civil wars, such as Sulla and Julius Caesar, used the title as a basis for more permanent power (fifth to first century вс ).
dux: Officers of the later Roman army (late third to sixth century ad).
dux (duces) limitis: Commanders of all troops (limitanei) within one of the regions into which the frontier provinces of the later empire was divided (late third to sixth century ad). equites singulares: The term used for the bodyguard cavalry attached to the staff of provincial governors under the Principate. These units seem to have been about 500 strong and were recruited from men seconded from the auxiliary alae (first to third century ad).
equites singulares augusti: The emperor’s own horse guards for
the first three centuries of the Principate, these provided an elite cavalry force to support the Praetorian Guard. They were recruited from the pick of the troopers in the provincial alae, and enjoyed very favourable service conditions and good chances of promotion (first to third century ad).
foederati: Allied barbarians obliged to provide military service to the emperor. They usually served in their own units and sometimes under their own commanders who usually held Roman rank. As time went on these became increasingly indistinguishable from units of the regular army, especially in the East (fourth to sixth century ad).
gladius: A sword, gladius is conventionally used to describe the gladius hispaniensis, the short Spanish sword which was the standard Roman sidearm until well into the third century ad. The weapon could be used for cutting, but was primarily intended for thrusting (third century вс to third century ad).
basta: A spear. It has proved difficult to associate the basta or the lancea firmly with a particular size or shape of weapon discovered in the archaeological record (fifth century вс: to sixth century ad).
hastatus (bastati). The first line of heavy infantry in the Republican legion, recruited from younger men (late fourth to second century вс).
Hippaka Gymnasia: The cavalry games which displayed the training of the alae of the Principate. Intended as a spectacle the troopers were dressed in bright colours and wore highly decorated armour (first to third century ad).
imaginifer: The standard-bearer who carried the imago (imagines), a standard with a bust of the emperor (first to third century ad).
immunes: Soldiers exempt from ordinary fatigues, usually as a result of possessing special skills (first to third century ad). imperium: The power of military command held by magistrates and pro-magistrates during their term of office (third century вс to third century ad).
laeti: Term applied to groups of barbarians settled by the emperor on land in the provinces under the obligation of providing recruits for the army. These rarely served in distinct contingents of their own (fourth to sixth century ad).
legatus (legati): A subordinate officer who held delegated imperium rather than exercising power in his own right. Legati were chosen by a magistrate rather than elected (third to first century вс). (1) Legatus augusti pro praetore: This title was given to the governors of the military provinces under the Principate, who commanded as representatives of the emperor (first to third century ad). (2) Legatus legionis: The title given to legionary commanders under the Principate (first to third century ad).
legion (legio): Originally a term meaning levy, the legions became the main unit of the Roman army for much of its history. Under the Republic and Principate they were large, predominantly infantry, formations of around four to five thousnd men, but by late antiquity most seem to have dwindled to a strength of about one thousand.
limitanei: The grade of troops commanded by the duces limitis, the military commanders of the various regions, usually on the frontier, into which the provinces of the later empire were divided (fourth to sixth century ad).
lorica: A corselet or breastplate. Three types of armour were most common. (1) Lorica hamata or ring-mail armour was probably copied from the Gauls. It offered good protection and was relatively simple, if time consuming, to manufacture. Its main disadvantage was its great weight, which primarily rested on the shoulders, although the military belt helped to transfer some of this burden to the hips (third century Bt: to sixth century ad). (2) Lorica squamata or scale armour was less flexible and offered poorer protection than mail. It seems to have been popular for most of the army’s history, perhaps in part because it could be polished into a high sheen and made the wearer look impressive (third century Bt: to sixth century ad). (3) Lorica segmentata is the name invented by modern scholars to describe the banded armour so often associated with the Romans. It offered good protection and its design helped to spread its weight more evenly than mail, but was complex to manufacture and prone to damage, which may explain its eventual abandonment (first to third century ad).
magister equitum: (1) Second-in-command to the Republican dictator, the Master of Horse traditionally commanded the cavalry, since the dictator was forbidden to ride a horse (fifth to first century Bt:). (2) Title given to senior officers of the later Imperial army, equal in status to magistri peditum (fourth to sixth century ad).
magister militum: Title given to the senior officers of the later Imperial army (fourth to sixth century ad). magister peditum: Title given to senior officers of the later Imperial army (fourth to sixth century ad). maniple (manipulus): The basic tactical unit of the Republican legion, the maniple consisted of two centuries. It was commanded by the centurion of the right hand (senior) century if he was present (late fourth to second century вс:). mattiobarbuli: Heavy, lead-weighted darts, often carried clipped into the hollow of a shield. Also known as plumbatae (third to sixth century ad).
military tribune (tribunus militum): Six military tribunes were elected or appointed to each Republican legion, one pair of these men holding command at any one time. Under the Principate each legion had one senior, senatorial tribune (tribunus laticlai’ius who wore a wide purple sash) and five equestrians (tribunii angusticlavii who wore a narrow purple sash), (first to third century ad). Military auxiliary cohorts and alae, or those with special status, were commanded by equestrian officers called tribunes who performed an identical role to auxiliary prefects. Some regiments of the later army were also commanded by tribunes.
numerus: A vague term meaning simply unit or band, numerus was the title given to many units of irregulars from a common ethnic background employed for frontier patrolling from the second century AD onwards. It was also applied to some units of cavalry in the later army.
onager: A one-armed torsion catapult designed to lob stones. It was simpler in construction than the two armed ballistae, but heavier, less mobile, and not as accurate. The basic design was to be followed by the Medieval mangonel (third to sixth century ad).
optio (optiones): Second-in-command of a century, the rank was symbolized by the carrying of the bastile, a shaft tipped with an ornamental knob (first to third century ad).
ovatio: A lesser form of the triumph, in an ovation the general rode through the city on horseback rather than in a chariot (fifth century вс: to first century ad).
palatini: Units of higher status and prestige than the comitatenses, the palatini also formed part of the field armies of late antiquity (fourth to sixth century ad).
pilum: The heavy javelin which was the standard equipment of
the Roman legionary for much of Rome’s history (third century вс to third century ad).
plumbatae: see mattiobarbuli.
praefectus castrorum: Third in command of a legion during the Principate, he was an experienced officer who was usually a former primus pilus (first to third century ad).
Praepositus: Unit commander of the later army, equivalent to a tribune (third to sixth century ad).
praetor: Praetors were annually elected magistrates who governed the less important provinces and fought Rome’s smaller wars.
Praetorian Guard: The military bodyguard of the emperors of the Principate, the Praetorians received higher pay and donatives and enjoyed far better service conditions than the legions. For most of their history they were formed into cohorts commanded by tribunes and the whole corps commanded by two Praetorian Prefects. No emperor could afford to alienate his guardsmen who represented the main military force in Rome or Italy. They were disbanded by Constantine in 312 after supporting his rival Maxentius (first to third century AD), prefect (praefectus): Equestrian commander of an auxiliary cohort or ala (first to third century ad).
princeps (principes): The second line of heavy infantry in the Republican legion, recruited from men in the prime of life (late fourth to second century вс).
principales: The three subordinate officers of the century, the optio, signifer and tesserarius (first to third century ad).
pseudocomitatenses. The grade given to units of limitanei who had become attached to the field armies (fourth to sixth century ad).
quaestor: Magistrates whose duties were primarily financial, quaestors acted as deputies to consular governors and often held subordinate military commands.
quincunx: The chequerboard formation used by the Republican legion in which the three lines were deployed with wide intervals between the maniples, the gaps being covered by the maniples of the next line. There has been much debate over the precise nature of this system, but it is clear that it gave the Roman legions far greater flexibility than the Hellenistic phalanx (late fourth to second century вс).
schola: The units of guard cavalry of the later Roman army. The scbolae provided many senior commanders from among their number (third to sixth century ad).
scorpion: The light bolt-shooting ballista employed by the Roman army both in the field and in sieges. They possessed a long range, as well as great accuracy and the ability to penetrate any form of armour (first century вс to sixth century ad). scutum: A shield, particularly the heavy, legionary shield. This was semi-cylindrical and usually either oval or rectangular. It was held by a single, transverse handgrip behind the central boss, although additional straps were used to support its weight on the march (third century вс to third century ad). signifer: The standard-bearer who carried the standard (signum) of the century. Under the Principate they administered the men’s pay and savings accounts (first to third century ad).
Socii: The Italian allies of the Republic, the socii formed alae which were normally equal in number or more numerous than the Roman troops in an army. After the Social War (90-88 вс) and the general extension of citizenship to most of the Italian peninsula the socii disappeared and all Italians were recruited into the legions (late fourth to second century вс:). spatba: The long sword used by the cavalry of the Principate and eventually adopted by most of the later army. It was well balanced for both cutting and thrusting (first to sixth century ad).
spolia opima: The highest honour which a triumphing general could claim was the right to dedicate spolia opima in the Temple of Jupiter Optimus Maximus on the Capitol. The right could only be gained by killing the enemy general in single combat and was celebrated on just a handful of occasions. tesserarius: Third-in-command of a century, the tesserarius traditionally was responsible for commanding the sentries. The name derived from the tessera, the tablet on which the night’s password was distributed through the camp (first to third century ad).
testudo: The famous tortoise formation in which Roman legionaries overlapped their long shields to provide protection to the front, sides and overhead. It was most commonly used to approach enemy fortifications and allow the legionaries to undermine them (third century вс to third century AD). triarius (triarii): The third and senior line of heavy infantry in the Republican legion, recruited from veteran soldiers (late fourth to second century вс:).
triumph: The great celebration granted by the Senate to a successful general took the form of a procession along the Sacra Via, the ceremonial main road of Rome, displaying the spoils and captives of his victory and culminated in the ritual execution of the captured enemy leader. The commander rode in a chariot, dressed like the statues of Jupiter, a slave holding a laurel wreath of Victory over his head. The slave was supposed to whisper to the general, reminding him that he was mortal. Under the Principate only members of the Imperial family received triumphs, but other commanders were granted the insignia of a triumph (ornamenta triumphalia) (fifth century вс to fourth century ad).
turma (turmae): The basic sub-unit of the Roman cavalry for much of its history, a turma consisted of around thirty men. Under the Principate it was commanded by a decurion (late fourth century вс to third century ad).
Urban cohorts: The paramilitary police force established by Augustus in Rome and a few other key cities, for instance guarding the Imperial mint at Lyon. They were organized into cohorts commanded by tribunes under the overall direction of the Urban Prefect (first to third century ad). veles (velites): The light infantry of the Republican legion, recruited from the poor or those too young to fight as heavy infantry. It is unclear whether they were identical to or superseded the rorarii, another term applied to light infantrymen in the Republican legion (late fourth to second century вс), vexillation (vexillatio): (1) A detachment operating independently, a vexillation might consist of anything from a few men to several thousand and could be drawn from several units. The use of these temporary formations designed for a specific role or operation gave the Roman army considerable flexibility (first to third century ad). (2) Many cavalry units of the later Field Armies were known as vexillations. They appear to have been similar in size to the old alae (fourth to sixth century ad). vexillum: A square flag mounted crosswise on a pole, the vex ilium was used to mark a general’s position and was also the standard carried by a detachment of troops (first to third century ad).
vigiles: The paramilitary fire-brigade established by Augustus in Rome, the vigiles were organized into cohorts, but not equipped with weapons (first to third century ad).