THE ARMY OF THE EARLY PRINCIPATE

 

OVERVIEW

The army depicted here is that commanded by the emperor Trajan during his Dacian Campaigns (101-102 and 105-106 CE), although it could be used more generically for any army fielded during the Early Principate (25 BCE-197 CE). The army of this period owed much to the martial traditions of the later Republic, with citizen legionary heavy infantry at its core, but Augustus regularized the recruitment, training, and equipment of the various support arms (henceforth known collectively as auxilia). During this period, the Romans also subsidized an extensive chain of buffer states along its borders (both within and outside the official borders), and these client states often provided the Roman army with various kinds of specialized troops to supplement the regular corps of the Roman army on specific campaigns. Usually, this was done only when the Roman army was operating alongside such client states to secure the territory along that border or to strike at an enemy beyond that border, but some of these allied units proved so valuable that they were hired to serve with the Roman army throughout the empire (e.g., Numidian light horsemen from North Africa, Balearic slingers from the islands off the eastern coast of Spain, Syrian bowmen from the eastern Mediterranean, and Sarmatian lancers from north of the Danube River). The army of this period conquered a vast empire, fighting against a wide variety of military systems in a wide variety of topographies, and amazingly did so without radical modifications to the empire's basic strategic posture or the tactical stance of its constituent units.

 

The advantages the Roman army enjoyed over its opponents during this period were in organization and corps discipline, logistics, and technology. Other peoples could field individual warriors who may have been as disciplined and well-trained as any Roman soldier (in some cases surpassing them), but few had a military doctrine that put heavy emphasis on drilling their troops to act as a unit. Those that did (the Hellenized kingdoms of the eastern Mediterranean) generally lacked the political unity and/or logistical genius of the Romans. The organization of each Roman army, with a command structure that reached all the way down to relatively small units with their own commanders (e.g., centuries commanded by centurions), allowed this unit drill to be carried out on a number of tactical levels, allowing for both rigid and highly mobile formations, as the situation demanded. Although the Roman army had iron discipline, subcommanders were encouraged to use their own initiative when they saw an advantage, and both individuals and units were picked out for either reward or punishment depending on performance. No army that Rome faced during the Early Principate had anything approaching the expertise in logistics enjoyed by the Roman army. Put simply, the Romans were consistently able to put the right number of men, in the right place, at the right time, and to keep them well supplied, while their opponents often failed to do so. Finally, while other peoples were able to match (or surpass) the technical skills of the Romans in specific areas (e.g., the production of weapons and armor), none could match them in either their ability to mass produce these items or in their ability to combine multiple high-quality technologies (e.g., high quality soldier's kit, high quality torsion and tension artillery, and effective military engineering techniques and equipment). This allowed the Romans to field large armies that were relatively uniformly equipped to a high standard, while opponents were generally only able to do so for a small proportion of their troops (e.g., nobles or other elites). Finally, the Roman genius for acquiring and modifying foreign technologies to work within the framework of their own system is legendary (e.g., the standard Roman infantry sword, the gladius, was derived from Spanish models).

 

COMMAND UNITS AND THE PRAETORIAN GUARD

At the time of Augustus' accession to power, it was common practice for Roman generals in the field to have a bodyguard of picked troops called a cohors praetoriae ("company of the command tent"). These units were like a legion in microcosm—a core of picked infantry supported by picked cavalry. A cohort was generally 500 men, but the Romans weren't always literal about such things, so the size and composition of such units depended on each general's preference and the resources he had available. When Augustus came to power and began his reforms of the Roman army, one of the first things he did was create (ca. 27 BCE) what amounted to a small private army, the Praetoriani (commonly known as the Praetorian Guards), whose official functions were to act as the garrison of Rome, to provide the emperor with an elite core of fighting men on campaign, and to provide the emperor with personal bodyguards. Unofficially, the Praetorians were used to intimidate the Senate—Augustus had a fort built for them right outside Rome, the Castra Praetoria ("Fort of the Praetorians")(it was against the law for any Roman general to bring armed troops within the sacred precincts of Rome, and Augustus was at pains to maintain the fiction of republican government). Policing the city was done by the vigiles, "watchmen," and the riot police, the cohortes urbanae, "urban cohorts," although the Praetorians occasionally operated within the city environs as the emperor's enforcers and bodyguards—this decision ultimately proved fateful, as the commanders of the Praetorians began to play an increasingly political role throughout the Principate. The Praetorians were, like the bodyguard units of other Roman generals, organized into cohorts, except the emperor had ten of them (the number fluctuated, but this was the number of Praetorian cohorts throughout most of the history of the corps). On campaign, the emperor could take as many Praetorian cohorts with him as he desired, but one—the Corporis Custodes Augusti ("Guards of the Body of the Emperor")—was always detailed to escort him wherever he went. From 27 BCE until 69 CE the Julio-Claudian emperors also maintained a personal bodyguard unit of Germanic mercenaries called the Germani Corporis Custodes ("German Guards of the Body of the Emperor"). Originally recruited from the Batavii and Ubii tribes—both of which had served Caesar well during his invasion of Gaul—these mercenaries were paid directly from the privy purse of the emperor (Praetorians received donatives from the emperor, but their regular payroll came from state funds). With the outbreak of the Batavian Revolt (69-70 CE), the idea of Germanic bodyguards for the emperor lost its appeal and the unit was disbanded. Trajan created another bodyguard unit (the date is uncertain) called the Equites Singulares Augusti ("Personal Cavalry of the Emperor"). Unlike the Praetorian cohorts, which were primarily infantry units with some cavalry, the Singulares were organized into an ala ("wing") consisting entirely of cavalry (generally between 1,000 and 2,000 cavalrymen). The Singulares were also the only Praetorian unit that recruited peregrini (provincial citizens) as well as cives Romani ("Roman citizens"). 

 

LEGIONS

The legiones ("levies") were the backbone of the Roman army—originally composed of both volunteers and conscripts, but by the Early Principate they had become standing battalions of professional soldiers. Recruitment into the legions was long limited only to Roman citizens, but during the reign of Trajan provincials were first allowed in, and by the end of the Principate even barbarians from beyond the borders could be recruited. The organization of each legion was built from the bottom up, with progressively larger units that could either operate independently or to fit into a cohesive whole. The smallest unit was the contubernium (“common tent”), consisting of eight men that shared a common tent and mess in camp, and carried many of their own supplies on the march (both on their backs and using mules). The contubernium was not a fighting unit (unless ambushed on the march), but a logistical division that allowed the Roman army to move very quickly and efficiently through any landscape. Next came the centuriae (“hundreds”), each commanded by a centurio (“hundred-commander”), and each consisting of 100 infantrymen (this was a paper strength, however, that was rarely actually achieved in the field due to injuries, sickness, casualties, etc.). This was the basic tactical unit that could either act independently or in conjunction with four other centuries to form a cohors (“company”) with a total of 500 infantrymen. The resulting cohort was commanded by one of that cohort’s five centurions, who held the rank of pilus prior (“leading spear”). Each legion had one double cohort (the cohors prior or “leading cohort”) of five double centuries of 200 men each. The commanding centurion of this double cohort was the primus pilus (“first spear”)—he acted as the commander of his own double century, of his own double cohort, and as the senior centurion of the legion. The cohort was a powerful tactical unit and the basic unit of maneuver for an army in the field. The first cohort (the double cohort) was often used as an independent strike force to achieve important tactical objectives within the larger battle scheme. A legion had ten cohorts, including the double cohort, for a total of 5,500 infantrymen (paper strength). Like the other tactical units, legions could act independently or in conjunction with other legions to create different-sized armies for different strategic needs. Each legion had a staff of senior officers, including five tribuni angusticlavii (“narrow-band tribunes,” a reference to the purple band they wore on their tunics that signified their social rank) that acted as staff officers and were often young noblemen learning how to command, a praefectus castrorum (“chief of the camp”) that was the legion’s chief logistical officer in charge of supplies (including the all-important legionary treasury) and was generally an experienced veteran, and a tribunus laticlavius (“broad-band tribune”) that acted as the legion’s senior officer and was generally a man of senatorial rank that had been appointed by the emperor. Overall command of a single legion or several legions that had been combined into a battle group was in the hands of a legatus legionis (“legionary envoy”), a man of senatorial rank (including scions of the imperial family) appointed by the emperor (and of course, the emperor himself could choose to command).

 

Symbolism became a powerful tool in the legions, and each unit had standards in the keeping of officers that also acted like priests. Each cohort had a signifer (“symbol-bearer”) whose role was to bear the signum (“symbol”) of that cohort, including a totem-like imago (“image”) of the unit’s patron god, patron emperor, or other religious symbol (usually a sculpture or image in some precious metal). The imago stood at the apex of a pole carried by the signifer, while other symbols (diplomae), such as awards for unit valor, were arranged beneath it. Moreover, each legion had an aquilifer (“eagle-bearer”) that carried a pole topped by the legion’s silver aquila (“eagle”), the standard totem of all the legions. Loss of these symbols in combat was viewed as a major disaster and had a profound psychological impact on the unit involved. It is a mark of the confidence and competence of the Roman army that these symbols were carried into battle in the vanguard. Each cohort also had a cornicen (“trumpeter”) whose duty was to relay audible signals to the unit regarding basic maneuvers (e.g., attack, retreat, etc.). In addition to the aquilifer, each legion had a vexillifer (“flag-bearer”) that carried a vexillum (“flag”) with that legion’s particular emblem and name on it. This flag was used in combination with a group of legionary cornicens to relay signals to the cohorts that were to be passed on to the soldiers. It was common to detach sub-units for various purposes (e.g., to brigade with under-strength units or to carry out independent tactical objectives), and these sub-units would also be given their own vexillum—thus these semi-independent brigades came to be called vexillationes (“flag units”). Each legion was designed to be as independent as possible, so rather than use a large number of distinct support units, legionaries with special skills were identified and tasked with operating in a number of support roles—cavalry dispatch riders and scouts, infantry scouts and bowmen, and artillerymen (discussed separately below). The legions had no separate engineering corps, but legionary infantrymen were given considerable training and practice in various engineering skills (road building, fort construction, bridge construction, and siege work), and there were those who excelled at such activities that acted as the legion's chief engineers.

 

Legionaries wore a corselet either of mail (lorica hamata) or scale (lorica squamata). Both covered the wearer's torso from about the upper thighs/groin to the shoulders, and had sleeves that hung down to mid-bicep.  For comfort and extra protection, a padded arming jacket (subermalis) was often worn beneath the corselet, and a thick scarf (focale) both prevented chafing and provided the throat with minimal protection. By the time of the Early Principate, most legionaries were wearing a style of helmet originally based on Gallic models known in Latin as the Galea ("Gallic"). This helmet continued to be refined and reinforced until by the end of the Principate there were models that provided substantial cranial, neck, and face protection. Crests were often worn for parade, but probably not for battle (except officers). For arms, Roman legionaries carried a variety of weapons, each with its own tactical uses, and so not all would have been carried simultaneously. Roman legionaries used a variety of spears (relatively heavy, used mainly for thrusting), javelins (lighter and used mainly for mid-distance throwing), and darts (small, but weighted, and used for relatively long-distance throwing). These included, but were not limited to, the hasta (the basic Roman spear), the gaesum (a Celt-inspired heavy spear), the pilum (a uniquely engineered Roman heavy javelin), the lancea (a light javelin), and the plumbata or martiobarbulis (lead-weighted throwing darts). The standard Roman infantry sword was the gladius, the Roman version having been based on an Iberian sword encountered by Republican Roman troops during the conquest of Hispania (Spain). The gladius was generally 2-3 feet long, with a double edge and a sharply tapered point. The gladius had decent cutting potential, but it was primarily a thrusting sword—Roman infantry were trained to use short, fast, physically economical underhand jabs. Roman soldiers also carried a short dagger called a pugio ("puncher") that was very similar in design to a push dagger (it had a very broad blade relative to overall length). Indeed, Roman authors tell us the edge was virtually useless, but it was devastating when used to stab an opponent. Roman legionaries also had recourse to a pickaxe called a dolabra. Normally, this was a tool used in various engineering activities (digging, chipping away at enemy fortifications, chopping wood, etc.), but it was a formidable weapon in its own right. There are some dynamic scenes depicted on Trajan's Column that show legionaries hacking down Dacian warriors with dolabra. Last, but certainly not least, is the legionary shield (scutum). As with the legionary helmet, the legionary shield evolved over time, but its basic design remained constant—it was constructed by gluing several layers of wood lathes together, creating a kind of light plywood, then it was covered with leather and painted canvas (painted with a legion-specific design), bound around the edges with a bronze or iron rim, and a bronze or iron boss (umbo) was bolted to the center (the handle was usually attached on the backside, behind the boss). Most of the iterations of the scutum were rectangular and at least partially curved. The shield was primarily a defensive piece of equipment, but it was also used offensively to perform a shield-punch that could knock an opponent off balance and create an opening for a lightening-fast thrust of the gladius.

 

Special note should be made of a few items of legionary armor. What most people consider to be the "typical" Roman armor is the cuirass of segmented plate called the lorica segmentata or lorica laminata. While it is true that this type of armor seems to have been used over a fairly large part of the empire for about three hundred years (roughly between the late first century BCE until the late third century CE), modern filmmakers have greatly exaggerated both its popularity with Roman soldiers and the time span of its use. It never achieved the ubiquity of mail and scale. Modern historical miniatures manufacturers and game designers also tend to follow the artistic conventions of Roman monuments (e.g., Trajan's Column) by portraying the lorica segmentata as exclusively legionary, despite the considerable amount of evidence that it was used by the auxilia as well. Roman sculptors tended to homogenize the appearance of different subjects to make them easily identifiable to viewers—while such a trope was and is undeniably useful as a kind of visual shorthand, it is not rigorously accurate. During Trajan's Dacian campaigns, some Roman soldiers augmented their torso armor with protection for the arms (manica) and legs (ocrea). The manica was similar in construction to the lorica segmentata, consisting of overlapping bands of bronze, iron, or hardened leather that extended from the shoulder to the wrist. Manica were usually only worn on the sword arm. Ocrea during this period were most often plate greaves that encased the wearer's shins and calves, sometimes with a projection that covered the knee. The reason for this added armor was the formidable Dacian falx, a two-handed sword with a scythe-like blade that Dacian warriors were adept at using to sever limbs. Roman officers tended to prefer muscled cuirasses of bronze, iron, or hardened leather, with several rows of laminated linen or hardened leather strips called pteruges ("feathers") hanging down from the shoulders and waistline to provide protection for the upper arms and hips/groin, respectively. Pteruges are a uniquely Mediterranean form of armor that gives Greek and Roman soldiers a distinct appearance.

 

AUXILIA

Auxilia (“supporters”) formed the standing regular non-citizen corps of the Roman army. By the end of the second century, the Roman army utilized a roughly equal number of auxiliaries and legionaries, including a number of specialized auxiliary troops (mostly archers and cavalry). Auxiliary troops were mainly recruited from free provincial subjects who did not hold Roman citizenship (peregrini). There is evidence that small numbers of Roman citizens were also admitted, and by the end of the second century barbarians (barbari, "babblers") from beyond the borders of the empire began to be admitted in increasingly large numbers. From the time of Augustus, auxiliary troops were organized into regular corps with standardized organization, training, discipline, equipment, and conditions of service. There were three primary types of auxilia—equites (“horsemen”), pedes ("footmen"), and sagittarii ("archers").

 

Equites were the Roman army's standard cavalry. They were organized into alae ("wings"), and as that name implies, they were usually used to guard the flanks of the infantry, but they were also used as a mobile reserve, to screen the deployment of the infantry, and to raid enemy territory in force. There were two types of ala—an ala quingenaria consisting of 16 turmae (“squadrons”) of 30 men each (total strength of 480 men plus commanders), and an ala milliaria consisting of 24 squadrons of 30 men each (total strength of 720 men plus commanders). There were also mixed infantry-cavalry units of auxilia, but in battle the cavalry elements of these units were brigaded with other cavalry and the infantry elements were brigaded with other infantry. The primary horse-breeding regions of the empire were in Spain, North Africa, and Thrace—most Roman horse breeds were relatively short and sturdy, although Spanish horses were reputedly fleet and spirited. Like all other cavalry of the time, Roman cavalry rode without stirrups. Auxiliary cavalry wore mail or scale corselets and bronze or iron helmets (although there is a single image of a Roman cavalryman on Trajan's Column who is wearing what appears to be a mail shirt with the shoulder pieces of a lorica segmentata). They used a flat oval shield (clipeus) similar to the Hellenistic thureos. Beginning in the first century CE, Roman cavalry phased out use of the gladius in favor of a longer cavalry sword (spatha), probably derived from the battle swords carried by Gallic cavalry in Roman service. However, the primary weapons of most Roman cavalry were a combination of spear (hasta) that could be thrust or thrown and light javelins (lancea), several of which were carried in a case hung from the saddle. Although the sword and spear gave auxiliary cavalry decent cut-and-thrust ability, they preferred circulating or sweeping formations on the battlefield, skirmishing with thrown javelins until a clear advantage presented itself to close for hand-to-hand melee (or to ride down fleeing opponents). Beginning in the reign of Trajan, and probably dating from his Dacian campaigns, the Roman army also began to develop contarii ("lancers") on the Sarmatian model. These were initially equipped like other equites, except the spear and javelins were replaced with a long (12-14 feet) lance called a contus ("barge-pole"). The contus was a two-handed weapon, so contarii did not carry shields (they usually compensated with heavier body armor). It is presumed that these lancers, like their Sarmatian counterparts, had a more aggressive tactical stance than ordinary equites, being more eager to charge home an attack (the long lance giving them a considerable advantage in reach over most infantry or other cavalry). Contarii didn't exist in significant numbers until after the end of the Principate. Another experimental unit of Trajan's were the dromedarii ("camel riders"). These were developed during his Parthian campaign, probably as scouts and caravan guards in the desert regions of Syria. This unit still used horses for combat—the camels were there for logistical purposes, carrying supplies and being ridden by cavalrymen when crossing desert regions, allowing the horses to rest.

  

The standard unit of organization of the pedes was the cohort. There were two types of cohort—the cohors quingenaria consisted of 6 centuries of 100 men each (total strength of 500 men plus commanders), and the cohors milliaria consisted of ten centuries of 100 men each (total strength of 1,000 men plus commanders). The auxiliary infantry were armed and armored almost identically to the legionary infantry, except the auxiliaries carried the oval clipeus shield instead of the legionary scutum. The auxiliary infantry were non-citizen peregrini (provincials), which meant they had lower social status than legionaries, but there is no evidence that the auxiliary infantry had a different tactical role than the legionary infantry—indeed, there is considerable evidence they were equal to the legions in everything except social status. As with the legionaries, what made the auxiliary cohorts so formidable was not a huge technological advantage over their opponents, but that every man in each unit was armed and armored to the same high standard (among most other peoples of the time, the breadth and quality of the equipment used by each warrior was determined by what he could afford or scavenge on campaign). Training, drilling, and discipline of auxiliary infantry were the same as for legionaries.

  

Prior to the Early Principate, the Roman army rarely used archers, and when they did, they did so by hiring foreign mercenaries or by relying on allied contingents. However, one of Augustus' military reforms was to create standing cohorts of auxiliary bowmen called sagittarii (“arrow-men”). There were three types of bow-armed auxiliary units—the cohortes sagittariorum were foot bowmen, organized as a standard auxiliary cohort (500-1,000 men); the alae sagittariorum were mounted archers, organized as a standard auxiliary wing (480-720 men); and there was a mixed unit of infantry and cavalry bowmen, although like standard auxiliary mixed units these men were brigaded with other units of like type (infantry or cavalry) for major battles. The auxiliary infantry archer cohorts could either act as independent units or they could be brigaded with other legionary or auxiliary infantry units as support archers. The mounted archers were used as skirmishers or scouts. Auxiliary archers were recruited mainly from Rome’s provinces in the eastern Mediterranean where there was a long tradition of martial archery. The majority of archer units were of Syrian origin, although there were units of Cretan, Thracian, and Anatolian origins. The Thracian, Cretan, and Anatolian units are often pictured dressed and equipped the same way as other auxiliary units (except with a bow and arrows instead of a spear and javelins, and no shield), while the Syrian units are either pictured unarmored with a cloth conical cap (the tartur cap was part of the traditional ethnic clothing of the Syrian peoples) and a long vest or wearing a mail or scale corselet over a long gown (the hem of the gown reaching to the ankles) with a conical bronze or iron helmet. As with all Roman depictions, these standards were probably mainly artistic conventions, in reality equipment probably varied, but it must have been based on something. All Roman archers used a sophisticated re-curve bow, once again originating with the Syrians. The Romans did develop a type of crossbow (manuballista, "hand-held bolt-thrower"), based on a Greek design (cheiroballistra), that was constructed almost entirely of metal, but it was not a very widespread weapon (probably due to its high cost of production and the high degree of technical skill needed to produce it). Users apparently acted like sharpshooters, picking out enemy officers and other high-value targets in battle.

 

ARTILLERY

Each infantry century (whether legionary or auxiliary) was supplied with a ballistae (tension artillery) and each cohort with a catapulta (torsion artillery). During sieges, additional (and usually larger) artillery would be built on-site. Ballistae operated on similar principles to the crossbow, using built-up tension in a cord pulled taut to fire a bolt that could range in size from an arrow to a large fence post. Some models fired round shot (stone or metal) instead of a bolt. The most popular design for field use was the scorpio ("scorpion") because it was relatively small and could be maneuvered into position and operated by a two-man crew. Two high-tech versions of Roman field ballistae were the carroballista ("cart-mounted bolt-thrower") and the polybolos (Greek, "multi-bolt thrower"). The carroballista was simply a bolt thrower mounted on a mule-drawn cart to give its crew both greater mobility and enough elevation to fire over the heads of infantry to their front. This allowed the crew to give direct fire support (like a sniper) to infantry without exposing the crew to a charge by the enemy. One war gamer I know refers to these as Roman flak-panzers. This would be a particularly apt description if the polybolos was ever cart-mounted. The polybolos was a repeating bolt-thrower capable of firing up to eleven bolts a minute by using a flat-link chain attached to a windlass. It should be noted that although modern reconstructions have shown the polybolos to be plausible (and not just Roman hyperbole), no archeological remains have been found to verify this weapon's existence. The cart-mounted ballista suffers the same problem, except we have a fortuitous image of them in operation on Trajan's Column, making their existence much more certain. Roman catapulta operated on the principle of torsion—a swinging arm was used to hurl objects with great velocity. Although the arm was usually set in motion with a tension device (usually twisted rope or animal sinew), the term "torsion artillery" is often used to distinguish catapulta from ballista. Like ballistae, catapulta came in various sizes, being capable of throwing stone or metal shot, or incendiaries (i.e., clay pots of flaming oil). The kick of catapulta when fired, due to the tremendous force released, led Roman soldiers to nickname them onager ("wild ass"). Catapulta were large, not easy to maneuver or aim, and required a fairly large crew to operate efficiently, so the Romans usually used them in siege warfare, but there were times and places when circumstances allowed them to be used as field artillery.

 

SYMMACHIARII, SOCII, FOEDERATI, and GLADIATORES

Symmachiarii (Greek, "allies"), socii (Latin, "allies"), and foederati (Latin, "treaty people") were the names applied to irregular units of foreign troops recruited from the numerous client kings and chieftains that Rome subsidized along the empire’s extensive borders, or that had been settled within the empire as pioneers expected to bring disused land into production. The larger nations (e.g., Armenia, Nabatea, Judea, and Commagene) could provide entire armies to assist Rome on specific campaigns in or near their country of origin, but there were also numerous smaller units called numeri (literally, "numbers," but meaning "mercenaries") that were contracted to serve in the Roman army alongside regular units, often for long periods of time and in lands far distant from their place(s) of origin. The service of numeri was governed by the provisions of a treaty (foedus)—in return for a generous subsidy from the imperial treasury, each mercenary commander agreed to supply a certain number of troops (sometimes of a certain type), units averaging around 300 men (although they could be considerably larger). Individuals that served in these units did so for pay and/or a share in the spoils. They supplied their own equipment and training and therefore retained their native character. Indeed, one of the main reasons the Roman army used these units was to take advantage of their specialized martial skills (not to mention the fact they were considered expendable). However, particularly successful units of numeri often became the core of new auxiliary units, being named after the ethnic origin of the troops (e.g., Cohors III Batavorum, "Third Cohort of the Batavians"). Entire tribes of barbarian peoples were re-settled within the empire as federates, and newly conquered peoples were often initially organized as federates—as stated above, they were settled on land the Romans wanted to bring into productive use or on land considered marginal, they were expected to bring this land into productive use, they were expected to defend their land as subjects of the empire (they were allowed to raise numeri to act as garrison troops for the lands in which they lived), and they were also expected to provide recruits to the Roman army (who would be incorporated into existing units of auxilia). Although these peoples usually became Romanized, they and the numeri they supplied to the Roman military often retained their native character for at least a generation (i.e., until the children raised as Romans grew up and replaced their barbarian-born parents), and as units drawn from these federated colonies grew in importance over time (by the end of the Principate) the term foederati supplanted that of numeri. Finally, gladiators (gladiatores) were not often used in the field, mostly because of well-justified fears about their loyalty. However, there were several notable instances during the Early Principate when an emperor used a combat unit made up of professional gladiators, usually with a promise of earning their freedom and receiving a donative to help them start a new life as a freedman. During the Year of the Five Emperors (69 CE), both Otho and Vitellius used large numbers of them (up to 2,000 on each side), and in 167 CE Marcus Aurelius needed to use levies of gladiators to supplement his legions, which had become depleted through casualties, famine, and desertions during the Marcommanic Wars (166-180 CE).