Stefan Yanakiev
2025
Auxiliary military units (lat. auxilia; from auxilium – help) are a specific type of troops with special skills within the Roman army, which are fully tailored according to the personnel assigned to it. Most often it is about people, non-Italians, capable of handling weapons uncharacteristic of Roman legionnaires. Such are the archers, slingers and light-armed units. Through Antiquity, the population of entire regions of Europe, Asia and Africa managed to improve their skills, and because of that, in the Roman army, there was a practice in which recruits from a specific region were used as reinforcement for certain types of troops. The inhabitants of the Balearic Islands are included in the auxiliary corps of the Slinger; those of Archers are most often made up of Crete, and from the Thracian lands – in mounted auxiliary units.
The other recruitment policy for securing professionals is based on the characteristics of individual tribes. The latter give their name to the unit in which they serve (e.g. from the Spanish tribe Lucensi = 1st, 2nd and 3rd Lucensian cohort; lat. cohors Lucensium). There are exceptions, and the Judean lands are one. Its population is excluded from the recruitment practice according to its religious preferences (Roth 2007: 417). The other exceptions apply to the most Greek cities along with the population in their territories. The prohibitions do not apply if individuals who wish to join in the ranks of the Roman army.
As an independent unit, the auxiliaries appeared as early as the time of the Republic (509 – 27 BC). One of their characteristics for the period is the nature of the service itself. The reinforcements sent by the allies of Rome and those obliged to give armies to subordinate cities were considered as auxiliary troops. They have their own distinctive gear and weaponry, which differs from that of the Romans (Fig. 2). In most cases, however, it concerns cavalry. During the time of the Principate (27 BC – 284 AD), the emphasis was on recruiting from the Roman provinces, while the population of the Italian Peninsula was exempted from this obligation.
The role and types of auxiliaries became important only after Octavian’s victory over Mark Antony at the Battle at Actium in the Adriatic Sea in 31 BC. Through his reforming activity, he initiated the imperial auxiliaries in their classical form, already known as auxilia (Speidel 2016: 80-95).
Soldiers of the Roman auxiliary stationed on the ramparts of a military camp repulse attacks by Decebalus’ warriors during the First Dacian War (101-102 AD), relief from Scene XXXII of Trajan’s Column © http://www.trajans-column.org
From the point of view of their construction, auxiliary troops can be of several types (see generally Hassall 2008: 332–334):
INFANTRY
Infantry (lat. cohors) is a standard tactical unit. Their construction did not differ significantly from the cohorts in the Roman legion. The smallest part is of 8 people who sleep in one tent (lat. contubernium). Ten contuberniums make one century (lat. centuria, eng. hundredth), whose number is 100 soldiers (80 soldiers + 20 men from the command staff and support). According to the number of centuries, the cohorts are of two types. If it is of the quingenarian type (cohors quingenaria; lat. quingenaria – five hundred), then the cohort consists of 6 centuries (i.e. between 480 and 500 soldiers in total). If it is of the milliary type (cohors milliaria; lat. milliaria – thousand), then it consists of 10 centuries (i.e. it is composed of 800 to 1000 men). The latter type was modeled after Ist cohort in the Roman legions, which were always extra large unlike the other nine cohorts. It is also the largest military formation of this type of troops. They do not form a larger one, similar to the legion (lat. legio), which is composed of 10 cohorts. The small composition facilitates the maneuverability of the unit during combat. The command was entrusted to a prefect of equestrian rank (in lat. praefectus cohortis) or a military tribune (in lat. tribunus militum).
CAVALRY
Cavalry (lat. sg. ala; pl. alae, eng. “wing”) is a fast-moving shock and reconnaissance unit. They were usually built on the sides of the legions. They consist of turmae (lat. turmae), in each there are between 30 and 32 men. Like the infantry units, they are divided into two types: the ala quingenaria is made up of 16 turmae, making a composition of approx. 480 to 512/600 horsemen, while the ala milliaria consisted of 24 turmae, which equated to 720/768 horsemen (with the potential to reach to 1000 due to the remaining personnel serving the unit). The commander-in-chief of this type of troops is the equestrian prefect (lat. praefectus alae).
MIXED
Mixed (so-called “horse cohorts”; lat. cohortes equitatae) is a specialized tactical military unit with specific tasks. They are distinguished by the fact that additional cavalry units (lat. alae) are added to the standard infantry units (lat. cohortes). The quingenarian part (lat. cohors equitata quingenaria) consists of 6 centuries (480 infantrymen) and 4 turmae (120 horsemen), and the total number of military personnel reaches 600 people. Accordingly, the milliary part (lat. cohors equitata milliaria) was composed with the combined forces of 10 centuries (approx. 800 infantrymen) and 8 turmae (240 horsemen), which makes approx. 1040 military personnel. They were entrusted to a prefect of equestrian rank (lat. praefectus cohortis) or a military tribune (lat. tribunus militum).
Image of two Roman auxiliaries foot soldiers (right) and a legionnaire (left) talking. They are easily recognizable by their rounded shields (clipeus), ringed or scaled cuirass, thin short-sleeved outer garment (tunica) and cloak (pallia); in contrast to the Roman legionnaires, who have the characteristic rectangular shield (scutum) and banded armor (lorica segmentata), relief from the Scene LVII of Trajan’s Column in Rome © http://www.trajans-column.org
The activity of the auxiliaries is reduced to four main functions (see generally Cheesman 1914):
OFFENSIVE
Offensive are expressed by participation in the campaigns and expeditions of Rome, with the maneuvers, arrangement, form and occupied positions on the field being fully coordinated with the military command. They often appear as the vanguard of the Roman army, lined up before the ranks of the legionaries, and therefore they give most casualties;
DEFENSIVE
This aspect is expressed in occupying key positions, providing them with sufficient opportunities to react in the event of an enemy attack. An important element for their efficiency is the military camp. It is a major supply and support station (Fig. 1).
PROTECTIVE
The activity of the auxiliary troops in this direction is expressed mainly in the monitoring and protection of vital thoroughfares. Regular patrols along pre-selected routes are often carried out in order to ensure the safety of the population. Particularly important here are the characteristics of the terrain, which dictate the type of military units (infantry or cavalry).
BUILDING
An important aspect of the activities of auxiliary units, expressed in the implementation of architectural projects, such as the construction of roads and public buildings. This function is most often used in peacetime. The main idea is to keep the militaries physically fit, but also to keep them engaged, since inactivity in the military encourages unrest, insubordination and riots with the potential to escalate into looting and rioting.
Usually, admission to auxillia occurs at the age of 16/17, and the service there lasts between 25 and 40 years. Exposed to the cold or heat in the camp of his military unit at a remote point of the Roman empire, overcoming the adversity of the attacks of the enemy and the betrayal of the comrade, the soldier who has proved his devotion to the Roman state and the emperor was given an honorable discharge (lat. honesta missio) after the end of his military service. It was initiated by the commander of the unit, and to establish the deed itself it was carried out in front of several witnesses, usually his comrades – all recorded on small copper plates known as military diplomas. They are issued in duplicate and are given to a person newly admitted to Roman society with the status of a veteran. The rewards for the years of service was expressed in the receipt (but not always!) of Roman citizenship (civitas Romana), a piece of land (lat. missio agraria) and/or a reward in cash (lat. missio nummaria). One of the two he keeps for himself, and the other diploma is given to the local officials of the settlement where he intends to settle. It proves his status and the benefits received.
The decline of the Roman auxiliaries occurred under the emperor Diocletian (286 – 305). He was the author of a number of military and administrative reforms that changed the structure of the Roman army. With them, the auxiliary contingents end their existence, and the militaries from now on participate in units with a radically different appearance and behavior.
REFERENCES
Cheesman, G. L. 1914: The Auxilia of the Roman Imperial Army.
Hassall, M. 2008: The Army. – In: Bowman, A. K., P. Garnsey & D. Rathbone (Edds.)., The High Empire 70–192. Cambridge University Press, 320–343. (= The Cambridge Ancient History, 11).
Roth, J. P. 2007: Jews and the Roman Army: Perception and Realities. – In: de Blois, L., Cascio, E. L. (Edds.)., The Impact of the Roman Army (200 BC – AD 476): Economic, Social, Political, Religious and Cultural Aspects. Proceedings of the Sixth Workshop of the International Network (Roman Empire, 200 B.C. – A.D. 476). Capri, March 29 – April 2, 2005. Leiden – Boston, 409–420 (Impact of Empire, 6).
Speidel, M. A. 2016: Actium, Allies, and the Augustan Auxilia: reconsidering the transformation of military structures and foreign relations in the reign of Augustus. – In: Les auxiliaries de l’armée romaine: Des allés aux fédérés. Actes du sixième Congrès de Lyon (23 – 25 octobre 2014). Lyon, 79–95.