 10 squads (contubernia - a tent group of generally 8 men) = a century,

each commanded by a centurion = 80 men [note that the size of a

century had diverged from its original, literal meaning of 100]
 6 centuries = a cohort = 480 men
 10 cohorts = a legion = 4800 men.

1 figure = 40 soldiers

2 figures = century

12 figures = cohort

12 x 10 = 120 = legion
 ROMAN AUXILIARIES – NOT
SECOND RATE TROOPS
April 4, 2018 - Hail Caesar, Roman, Uniforms & History - Tagged: Hail Caesar, Romans

This article, by Dr Phil Hendry, aims to dispel the myth that the Roman war machine was all about the much-
lauded Legionary and that Auxiliary units were bit part players. Over to you, Phil…

Phil: The aim of this article is to show that Auxilia are much better troops than most wargamers believe them to
be. We will examine the reasons wargamers have for believing that they are so inferior and examine the reality,
as far as we know it, of the Auxilia – their nature, the structure of their units, and why wargamers need them.
There are a number of misconceptions regarding the nature and employment of the Auxilia. These include:
i. the inferiority of the auxilia, in both training and equipment, when compared to the legions;
ii. that the legions were heavy infantry, whilst the auxilia provided only light troops;
iii. that the main battle-line was the preserve, exclusively, of the legions, being supported on the flanks
by the light troops of the auxilia (this would make sense if (ii) above were true – however, as we shall
see, it is not);
iv. auxilia were only support troops, incapable of mounting independent operations themselves, only ever
helping the legions;
v. the auxilia were border troops, manning frontier forts, whilst the legions provided a ‘strategic reserve’,
being based well back from the frontier, and only intervening in the event of a major invasion which
the auxilia could not repel unaided.
Most of these misconceptions stem from a too-literal reading of ‘De Re Militari’ (also known as ‘Epitoma rei
militaris’) by Publius Flavius Vegetius Renatus (hereafter referred to as ‘Vegetius’). The author of this work
wrote sometime after the death of Emperor Gratian (383AD). It seems likely to have been written in the reign of
the Emperor Theodosius I, who reigned from 379 to 395.
Vegetius is the only ‘manual’ of the Roman military to have survived ‘intact’. However, we should note that,
firstly, Vegetius himself had no military experience whatsoever, and secondly, that his work is a carelessly
constructed compilation of material from a vast range of sources and periods, all jumbled together. As such, it is
very hard to ‘unscramble’ it enough to make sense of it and to decide which parts are relevant to which era.
Let us take each of the misconceptions in turn, and see what we make of them.
 i. The only evidence we have for the auxilia being inferior, stems from: (a) comments in Vegetius –
(written much later than our period, and containing all sorts of concepts, from all sorts of periods, all
mixed up, making it frustratingly difficult to interpret), in which he says that young men preferred to
join the auxilia in order to escape the harsher discipline and training of the legions; (b) from the reliefs
of Trajan’s column, which was erected to extol the glory of Trajan and his legions in the wake of the
hard-fought, but ultimately successful, campaigns in Dacia. To me it is a pure recruiting poster: bung
up a darned great monument to the legions, showing their triumphant victory, so as to say to the
citizens: ‘join the army and kick barbarian butt’. The auxilia very much play second fiddle to the
legions on the column but, I contend, this has nothing to do with reality, and everything to do with
propaganda. There’s very little, if any, evidence from the archaeology that the auxilia were trained or
equipped in an inferior fashion. If they really were so inferior, why were they paid as much as 4/5 of
legionary pay, despite not being Roman citizens? The Romans weren’t stupid!
ii. This again stems largely from Trajan’s column and is down to the ‘convention’ that legionaries are
shown in lorica segmentata, whilst auxiliaries aren’t, and that legionaries are shown with the large
rectangular scutum (most suitable for fighting in close formation), whilst auxilia are shown with oval
shields. Vegetius also does his best to mislead us: “auxilia are always joined as light troops with the
legions in the line”. It is true that some specialist units in the auxilia, such as Syrian archers and
Numidian cavalry, wore light armour (or none). But they were a small minority of the auxilia. Most
auxiliary cohorts contained heavy infantry similar to legionaries – wearing mail and helmets, carrying
spears and large shields (though, possibly, oval as opposed to rectangular).
iii. This is plainly not true – there were a number of battles, Mons Graupius (somewhere in Northern
Scotland, where the Romans defeated the Caledones) being a case in point, where the legions stood
back and let the auxilia get on with it – most of them were, after all, equipped as heavy infantry, so
why not use them in the role for which they were equipped? And for them to form part of the main
battle line would be a continuation of the practice during the Republic, when the Citizen legions
formed up in the centre, flanked by the ‘Socii’ (allies), who were essentially armed and equipped in
the same manner as the Citizens – and are the precursors of the auxilia.
iv. See (iii) above. Roughly twenty major battle scenes are shown on Trajan’s column. Despite the
column’s seeming bias against the auxilia, they take part in nineteen of these, and in twelve they are
unaccompanied by legionaries.
v. There is no shortage of evidence for the presence of legionaries on or near the frontiers. It has to be
said that in Britannia the legionary bases were well back from the frontier (unlike, for example,
Germany), but vexillations (detachments) often seem to have been on or near the frontier. And if you
insist that only the legionaries wore lorica segmentata, well, bits of the stuff turn up very frequently in
digs on auxiliary forts where it clearly shouldn’t be found. Of course, this latter point could be taken
the other way too – perhaps auxilia did wear lorica segmentata after all!
In conclusion, there were few significant differences in training, fighting capability or tactical role between
legionary infantry and their auxiliary counterparts – it seems as though either could fight in the main battle- line
or act as light infantry. I suspect that the auxiliaries were often given the ‘dirty jobs’ where taking a few
casualties wouldn’t matter (it was probably bad form to get citizens killed unnecessarily). The legions, on the
other hand, were more or less guaranteed to be reliable and would be used where success was imperative,
regardless of casualties.
In cavalry, auxiliaries were superior, as they were combat-capable, whereas it seems that the small contingent of
legionary cavalry were not (they seem mostly to have served as messengers). In archery, legions seemingly had
no capability at all.
When it comes to rates of pay, it seems that the auxilia weren’t all that much different to the legions – in mid
First Century AD, an auxiliary infantryman was paid 180 denarii per annum, whilst legionary infantryman
received 225. The Romans weren’t stupid and I can’t see them paying 4/5 of a legionary salary to a soldier who
is markedly inferior to his legionary counterpart.
In view of this, it seems clear to me that the auxilia are worthy of further study, and worthy of a more prominent
place in our armies of little men. So, let us consider the auxilia, their organisation, and how and why this might
be different to the legions.
ORGANISATION
Unlike the legions, which were monolithic structures of 5,000 men, all more or less alike, the auxilia were
organised in smaller units, of several different kinds. The easiest way to explain the differences is probably in
tabular form – see opposite.

Unit Sub-unit No of Sub-unit Unit

Unit Type Service C o mma n d e r C o mma n d e r s u b - u n i t s s t r e n g t h s t r e n g t h

Ala
quingenaria cavalry praefectus decurio 16 turmae 32* 512

Ala milliaria cavalry praefectus decurio 24 turmae 32 768

Cohors
quingenaria infantry praefectus decurio 6 centuriae 80 480

Cohors tribunus 10
milliaria infantry militum* centurio centuriae 80 800

Cohors 6
equitata mixed centurio (inf), centuriae, 600
quingenaria infantry/cavalry praefectus decurio (cav) 4 turmae 80, 30 (480inf/120cav)

Cohors 10
equitata mixed tribunus centurio (inf), centuriae, 1,040
milliaria infantry/cavalry militum* decurio (cav) 8 turmae 80, 30 (800inf/240cav)

* There is some debate about the strength of the turma between 30 and 32 men. 30 was the size of a turma in the
Republican cavalry and in the cohors equitata of the Principate (early empire) auxilia. Against this is a statement
by Arrian that an ala was 512 strong. This would make an ala turma 32 men strong. Personally, I suspect it
simply comes down to whether one counts the commander and standard bearer, or just the troopers, in the total.
** Batavian and Tungrian cohortes milliariae seem to have been commanded by a praefectus
As can be seen from the table, there are several different kinds of units. Superficially at least, the infantry
cohorts resemble those of the legions – in particular the cohors quingenaria are very similar to the ordinary
cohorts of the legions except that the legionary cohort seems not to have had an overall commander – meaning
that it was not capable of independent action, unless the legate appointed ‘someone’ to take command – perhaps
one of the tribunes or a senior centurion?
If one examines the deployment of auxiliary units, it can easily be seen that it was rare to deploy units from the
same province together. It was also the aim that units wouldn’t serve in their own province. This was intended to
reduce the chance of rebellion: if the biggest formation in any given province was a Roman legion, it was likely
to prevail in the case of any of the auxiliary units revolting.
Of course, a lot of auxiliary units recruited new troops in the provinces they were stationed in, as well as
(sometimes?) receiving some from their ‘home’ province, so the original ethnic character gradually became
diluted. To these pools of recruits can be added the sons of the veterans.
Soldiers were not, officially, allowed to marry, but it seems that a lot did. When (if!) they completed their
service and were discharged, they automatically became Roman citizens, as did their children (but not their
wives!). Being citizens, their sons would be eligible to join the legions, rather than the auxilia, but many seem to
have joined their father’s former unit. Thus the auxiliary units were not purely made up of non-citizens. Of
course, the officers (tribunes, prefects, centurions and decurions) were usually Roman citizens.
THE AUXILIA IN BRITANNIA
Britannia was perhaps the most ‘militarised’ of any province – at any given time it had a garrison of about 10%
of the entire Roman army. The ‘Brittunculi’ must have been really horrid!
In addition to either three, or (sometimes) four, legions (the number varied a bit over the years, but was never
less than three) there were up to about fifty units of auxilia in the province – for instance, in 130 AD, we think
that there were 11 cavalry alae (one of which was a milliary ala), and 45 cohorts (of which 11 were milliary) –
of course, some of the latter were infantry, and some were mixed units. Numbers-wise then, any army in Britain
is likely to consist mostly of auxilia.
A minor point on ethnicity and the naming of units – it doesn’t necessarily follow that a unit entitled ‘The
Fourth Dacian Wing’ actually had any connections with Dacia whatsoever. Dio Cassius describes how a cavalry
unit was formed with the title ‘Batavians’, simply on the basis that Batavians had a reputation for superb
horsemanship – there isn’t a shred of evidence that any Batavians ever actually belonged to it.
SPECIALISED UNITS
In addition to the regular auxiliary units, there were a number of units which had particular functions. In the
days of the Roman Republic, there were just three types: Balearic slingers, Cretan archers and Numidian light
cavalry.
During the Principate, this increased to include other specialised types:
Sagittarii (archers) – alae sagittariiorum (mounted archers), cohors sagittariiorum and cohors sagittariiorum
equitatae (mixed mounted and foot archers) – just one unit is listed for Britannia, The First Cohort of Hamian
Bowmen;
Equites Maurorum (Moorish horsemen), though how many units of these fought in their traditional ‘barbaric’
fashion, and how many fought, and dressed, as ‘regular’ auxiliary cavalry is unknown;
Funditores (slingers) – oddly, no record of any units is known from the Principate, though slingers are depicted
on Trajan’s Column;
Dromedarii – camel-mounted units: just one of these is attested from the 2nd century, ala I Ulpia
dromedariorum milliaria in Syria, but surely there must have been more to patrol the deserts of Arabia and
North Africa;
Exploratores – reconnaissance units (from explorare – to scout) – examples include two numeri
exploratorum attested in the 3rd century in Britain: Habitanco and Bremenio (both names of forts).
IRREGULAR UNITS
Throughout the Principate period, there is evidence of ethnic units of barbari outside the normal auxilia
organisation fighting alongside Roman troops. The gradual inclusion of greater numbers of this sort of troops
into the military was taken a further step by the creation under Hadrian (who reigned 117-138 AD) of a new
type of force in addition to the legions and auxilia, known as numerii. Formed in bodies of around 300 irregular
troops, the numerii were drawn largely from the peoples of client-states – i.e. ‘allied’ states from beyond the
borders of the empire, as well as more ‘barbaric’ peoples from within the empire. They were both less
regimented and less Romanised than normal auxiliary troops, with a “pronounced national character”, including
native dress, native war cries, and being led by their own leaders. The introduction of the numeri was a response
to the need for cheap troops, who were nevertheless fierce and provided a force balance of light infantry and
cavalry. In wargames terms, using a unit or two of troops who would normally be seen as ‘enemies’ would fit
the bill admirably.
Get yourself some auxilia (or numerii!) – it’s the perfect excuse to relieve the (elite) monotony of wall-to-wall
legionaries! Variety is the spice of life and all that. Seriously though, the Romans used auxilia, and if we want to
be true to the period, so should we. In my view, they don’t just add colour, they also make your army more
capable – without them you’re not going to have much in the way of cavalry, light infantry or missile-armed
troops.
Finally, a throw-away remark someone made about the First Cohort of Hamian Bowmen made me think for a
moment. It’s not clear quite why the garrison of Hadrian’s Wall should include a unit of archers. Someone
suggested that perhaps they were stationed there to provide a source of fresh meat for the rest of the garrison by
hunting. If this was the case, then presumably a few would be stationed at each fort – maybe this is why an
archer’s tombstone was found at Vercovicium (Housesteads) on Hadrian’s Wall, when they were actually based
at Magnis (Carvoran) on the Stanegate.

As you can see we have plastic multi-part Roman Auxilia and they come with a stunning metal command group
of Centurion, Optio, Cornicen and Signifer.

View in store
View in store
We also have a set of Roman Auxiliary horsemen armed with swords. These brave cavalrymen also come with
sheaths of javelins. The helmets are of a different style to those armed with spear above so you can field two
very distinct units.

View in store
Giving your army missile capability is another facet of the Auxiliary’s flexibility. We have two types of
Auxiliary archers available – the Western Archers, dressed in traditional Roman gear above…

View in store
 …or the Eastern Archers who don the garb of their homeland – conical helmets and long robes under their
chainmail. They also differ from their Western counterparts in using thumb-rings to draw their arrows rather
than grasping them between forefinger and them.

All you want to know about the Roman army

 You many need the glossary of Latin terms for this page.
 Also consider looking at the rank structure of the Roman army.

1. The Roman Army

The army of the empire – the principate.
The power of the Roman emperors rested on their control of massive armed forces,
paid for out of the emperor’s privy purse and bound to him by an oath of personal
allegiance. The vast majority of soldiers were stationed in so-called imperial
provinces, commanded by direct appointees of the emperor. The Roman imperial
army was thus in effect very much a private army.

The imperial army was a standing professional army. It contained both conscripts
and volunteers serving a minimum term of sixteen years, though most had to serve
for 25 years or more before they were up for retirement. To preserve the loyalty of
the soldiers on which their position of power rested, the emperors looked well after
their interests. Pay was regular and comparatively generous and on occasion
supplemented by donativa, special bonuses of up to five years pay. On completion of
their term of service soldiers received a large retirement grant of thirteen to
seventeen years’ worth of pay. In addition to these monetary rewards serving
soldiers and retired veterans were also granted numerous legal privileges.

The army of the empire was like its republican predecessors made up of a variety of
different units. The most important divisions were however made between the
legions, the auxiliaries, the fleet and the imperial guards. It are these main branches
of the armed services that will be briefly discussed below.

The legions
The core of the Roman army was formed by the units called legions from the
Latin legio, meaning a levy. During the first three centuries of the empire the army
contained no more than 25 to 34 legions. Each of these units consisted of about
5000-6000 men recruited among the citizen body. Although the soldiers of the legion
were Roman citizens, this did not imply that they originated from the city of Rome or
even Italy. With the spread of the franchise among the population of the conquered
territories provincials quickly became the most important source of recruits. Italian
levies however remained the most usual source for newly raised legions, although
several units were formed using marines or legionaries detached from existing
formations.

The legio was a miniature army that contained within its ranks troops trained and
equipped to perform all kinds of different duties both on and off the battlefield.
Although the vast majority of soldiers served as heavy infantry, other legionaries
fought as cavalry, archers or light infantry. Other specialised troops operated artillery
consisting of torsion guns. The troops were however not solely prepared for combat.
Legionaries regularly served as combat engineers constructing fortifications, roads
and bridges. As the legion counted among its complement a vast number of men
with special skills it was in many ways self-supporting. A large part of its military
equipment could be produced by artisans in the ranks. Soldiers trained as surveyors,
engineers and architects ensured that the legion needed little outside help for its
building requirements. Administrative duties were performed by other legionaries
both within their unit as well as in the provincial bureaucracy.

Each legion carried a number and a name, e.g. legio X Gemina (the tenth ‘twin’ or
‘double’ legion), to which honorary titles like pia fidelis (dutiful and loyal) could be
added. The numbering and naming of units followed no rationalised pattern. As
many of the formations originated in the various armies of the civil wars following the
death of Julius Caesar, several legions carried identical numerals or nicknames.
Even new legions that were levied were named and numbered according to diverse
systems. The sense of individuality provided by these numbers and titles was
reinforced by the use of different unit symbols and signs like bulls, boars or
capricorns.

The organisation
The strength and organisation of the legions varied in time and was probably not
completely standardised throughout the army. Generally speaking however
the legio was organised in ten cohortes or cohorts. These cohorts consisted each of
three manipuli, literally ‘handfuls’, which were in their turn subdivided in
two centuriae or ‘hundreds’. These centuriae were composed of a number
of contubernia or ‘tentparties’. Although the name centuria would seem to indicate a
unit of a hundred soldiers, this unit could comprise anything from 30 to over 200
individuals. The usual establishment strength however is thought to have been 80
men. From the second half of the first century AD in at least some of the legions the
first cohort was reorganised in five double strength centuriae while the remainder
continued to be organised in the old manner.

In addition to the regular organisation of cohortes, manipuli and centuriae of the

legionary heavy infantry there were other subunits for the equites legionis, the
legionary cavalry, and the antesignani or lancearii, the elite legionary light infantry.
The exact details of their organisation are as yet not very clear. For a variety of
duties provisional units known as vexillationes or numeri were formed. The strength
and organisation of these provisional units varied greatly and was only in part based
on the more regular subdivisions of the legion.

The officers
Command of the legion was usually given to a legatus legionis picked by the
emperor from the senatorial class who generally had some previous military
experience through service as a tribunus. In Egypt and from the start of the third
century also in other provinces the command was not entrusted to a
senatorial legatus, but to a praefectus legionis, an acting commander drawn from the
equestrian order. The legionary commander was assisted by six military tribunes.
With the exception of the units stationed in Egypt one of these tribuni was usually a
young senator at the start of his public career. Known as a tribunus laticlavius from
the broad purple stripes on his tunic this senior tribune was second-in-command. His
collegues from the equestrian order were known as tribuni angusticlavii and
generally had done earlier service as a commander of an auxiliary infantry unit. A
former senior centurion usually performed the duties of praefectus castrorum, camp
commandant, and was the third in the chain of command.

The most important officers in the legions were the centuriones. These men were
partly directly recruited from the Roman knights or the city councilmembers, but the
greater part of the centurions had previously served as soldiers and NCO’s in the
legions or the praetorian cohorts. Depending on the organisation of the legion either
sixty or fifty nine centuriones ordinarii commanded the centuriae, while a varying
number of centuriones supernumerarii were employed for special duties. These
officers were known by titles derived from the place of their units in the old battle
order. The hastatus prior, princeps prior and pilus prior were the higher ranking
officers commanding the manipuli. The hastatus posterior, princeps
posterior and pilus posterior acted as their deputies. The cohorts were under the
command of the pilus prior. Distinguished from their fellow officers were the primi
ordines, the senior centurions of the first cohort of the legion. These men had
achieved their posts by prior service in other postings and were chief advisors of the
legionary commanders. The post of primus pilus, the highest ranking centurion in the
legion, carried great prestige and assured entry into the equestrian order.

An uncertain number of supernumerary centurions performed a variety of tasks both

within the legion itself and in other units. Centuriones exercitatores for example were
used as training officers for the legionary cavalry and the horse guards of provincial
governors and the emperor. Acenturio stratorum was employed to oversee the
remount system of the provincial armies and on occasion to command
the singulares, the auxiliary soldiers serving as a governor’s guard. The centuriones
lanceariorum led the elite legionary infantry known as antesignani or lancearii. Other
supernumerary officers performed duties in the medical service of the legions.

The non-commissioned officers

To assist the officers the legion counted a number of NCO’s among its strength.
These men were known as principales and depending on their status received
as duplicarii double pay or as sesquiplicarii pay and a half. Each centurio
ordinarius had an optio as his deputy. Whereas the centurion led his men from the
front, the optio was stationed at the rear of the unit to keep the legionaries from
shirking away in combat. The signifer or standard bearer carried the signum of the
unit. This standard served both as a rallying point for the soldiers and to
communicate simple visual commands to the troops in battle. The task of carrying
the signum in battle was dangerous as the soldier had to stand in the first rank and
could carry only a small buckler. It may not be strictly coincidental that available
epigraphical evidence contains a relatively large number of discentes signiferorum,
trainee standard-bearers. The signifer also assumed responsibility for the financial
administration of the unit and functioned as the legionaries’ banker.
The tesserarius was a third NCO attached to a centuria and in charge of the
distribution and collection of the watch words. Both optio and signifer received
double pay, but the tesserarius attached to a centuria was on pay and a half.
Other principales like the cornicularius were attached to the administrative offices of
the legion.

A considerable number of legionary soldiers were classed as immunes. These men

were exempted from the more tedious chores because of the special tasks they had
to perform, but received no extra pay. As many a soldier without immunity was
forced to bribe his centurion to escape the less desirable duties, the immunes would
in practice have had some financial gain from their position. Among
the immunes were musicians, military police, cavalry troopers, drill and weapons
instructors, artisans, clerks and medical orderlies. It was usual for
both immunes and principales to have served several years as a munifex, a private
liable for all kinds of duty and fatigues, before they received promotion. Most, if not
all, positions were reached after a period of specialised training as a discens.
The auxilia
The imperial Roman army continued the republican tradition of supplementing the
citizen legions with units recruited from peregrini, non-citizens from conquered or
allied communities. In the imperial army the total numerical strength of the various
auxiliary formations was roughly comparable to that of the legionary troops. These
forces were known as socii or auxilia and were composed of both regular and
irregular formations. Many modern works distinguish regular auxilia consisting
of cohortes and alae from irregular numeri. This present day division disregards the
fact that irregular units could be designated as a cohors and that numerus was a
very generic term which was also in general use for regular army units. As in
the legiones draftees and volunteers served side by side in the auxiliary forces. With
the spread of Roman citizenship among the population of the conquered territories
the auxilia were increasingly recruiting citizens into the ranks, blurring the original
division between peregrine auxiliaries and citizen legionaries.

The imperial auxilia were composed of a variety of units. Infantry units were
generally organised in cohorts that in the case of cohortes equitatae could include a
small mounted force. Cavalry was usually formed into alae or ‘wings’.
Both cohortes and alae could comprise either quingenaria units of approximately 500
man or milliaria formations of 800-1000 soldiers. Infantry cohorts with a mounted
contingent had an additional 120 to 250 cavalry troopers. Infantry cohorts were
composed of three to five manipuli of each two centuriae. Cavalry alae counted 16 to
24 turmae of 30-40 mounted soldiers. Auxiliary formations were usually commanded
by a praefectus cohortis or praefectus alae, though a tribunus cohortis or
legionary centurio was occasionally employed. Some of these commanders were
drawn from the tribal aristocracy, though most were recruited from the equestrian
order. Command of a cavalry alae was only entrusted to men who had previously
served as a praefectus cohortis and legionary tribunus. The infantry subunits had
similar officers and NCO’s as their legionary counterparts. Cavalry turmae were
placed under a decurio instead of a centurion. Legionaries were regularly transferred
to act as officers and NCO’s in the units of the auxilia.

Units in the auxiliary forces carried like the legions a number and a title. The
numbering of units followed different patterns and partly reflected the order in which
troops had been levied. The names of units varied greatly, many
like cohors I Batavorum being derived from the tribe that provided the original levies,
others reflecting the armament, e.g. the ala I contariorum, or honouring a former
commander, for example ala Siliana. Redeployment of units and the Roman practice
of local recruitment of replacements meant that the ethnic titles borne by formations
did not reflect the actual origins of its soldiers.

The infantry of the auxilia consisted mainly of soldiers trained and equipped to fight
in a way comparable to that of the legionary heavy infantry. In addition to these
existed specialised formations of light infantry adept at fighting in a looser order.
Units of archers formed a large proportion of the available auxiliary forces.
The alae were for the larger part made up of medium cavalry suited for both
skirmishing and shock tactics. Formations of mounted archers were also much
employed. A minority of the cavalry units were composed of heavy cavalry troopers
armed with the contus, a two handed cavalry spear. These soldiers and some of
their mounts as well were heavily armoured. In at least part of the medium
cavalry alae a number of troopers used to fight as horse archers or heavy cavalry
giving the unit a wider range of combat capabilities.

From the auxiliary units of a provincial army a number of soldiers were selected for
service in the singulares of the governor’s guard. Infantrymen from the cohorts were
grouped in the pedites singulares while horsemen from both cohortes
equitatae and alae were brigaded in the equites singulares. Both units were trained
and commanded by legionary centuriones. The strength of these guard formations
was probably related to the numbers of troops deployed in a province. The fact
however that regular army formations like the ala singularium were formed from such
elite units seems to indicate a strength of approximately 500 for both infantry and
cavalry singulares. As promotions in the Roman army were as much depending on
personal relations as on merit, men serving in the governor’s guard could look
forward to better army careers.

The service conditions

There is much debate on the actual service conditions enjoyed by soldiers serving in
the auxilia. Recently published evidence seems to indicate that basic pay under
the principate was either 1/6th part less or even equal to that of the legionaries.
Auxiliaries were also included in the occasional distribution of donativa. These
similar service conditions help explain why legionary soldiers were transferring freely
to posts in auxiliary units. An important service condition for non-citizens enlisted in
the auxilia was the grant of Roman citizenship. Generally this was awarded after 25
years of service, though on occasion grants were made during service as a reward
for bravery in battle. An additional retirement grant of money for the auxilia is very
likely, though the evidence available is ambiguous. The often cited difference in
dimensions of the living space between the larger bases of legions and the smaller
frontier forts may not have served to accentuate status differences between the
legions and auxiliaries. Not only were legionary soldiers regularly stationed in the
smaller forts, but the larger forts were also in part garrisoned by units of the auxilia.

The imperial guard

The Roman emperor had several guard units at his disposal. The most important of
these were the cohortes praetoriae or praetorian guard. During the reign of the Julio-
Claudian dynasty the Germani custodes corporis or German bodyguard provided
additional security. From the accession of Traianus the equites singulares
Augusti recruited among the auxiliary cavalry formed the emperor’s horse guard. The
majority of these men served as guards, i.e. picked troops, rather than bodyguards
directly watching over the person of the emperor. These elite forces at the emperor’s
immediate disposal formed the nucleus of the field armies assembled for imperial
military expeditions. Smaller numbers of soldiers were selected among the guard
units for personal protection duties.

The praetorian guard

Under the republic Roman generals had usually formed a guard unit named cohors
praetoria after the praetorium or HQ. Under the empire such units became a
privilege reserved for the emperor under whose auspicia all military operations were
conducted. Augustus originally formed nine numbered cohortes praetoriae consisting
of both infantry and cavalry billeted at Rome and some other Italian cities. This
number was later raised to ten units and the cohorts were concentrated in a large
base adjacent to Rome. Command of the praetorian guard was entrusted to one or
two equestrian praefecti praetorio. Three additional cohortes urbanae with a similar
structure were also present at Rome, but not under the direct control of the
praetorian prefects.

A praetorian cohort consisted of approximately 500 infantrymen organised

in manipuli and centuriae and under the overall command of a tribunus. This strength
was doubled in the course of the first century AD. The majority of praetorians fought
as heavy infantry with smaller numbers acting as light infantry lancearii and archers.
Added to these foot soldiers each cohort contained a number of cavalrymen. The
combined equites praetoriani numbered at least 400 men and may even have been
a thousand strong. Other troopers were known as equites speculatores and served
as bodyguards to the emperor. The praetorian cohort that guarded the imperial
palace and accompanied the emperor in the city of Rome was known as the cohors
togata. As their duties were performed within the pomerium, the sacred boundary of
the city, these soldiers could not wear full armour and equipment and therefore
dressed in civilian togae, though keeping their swords at hand.

Service conditions in the praetorian cohorts were better than in the legions. Pay was
substantially higher and donativa were more frequent. The term of service of sixteen
years compared favourably to the 20 to 25 years in the legions. Promotion
opportunities were also excellent. A large part of the legionary posts as centurio was
filled by former praetorian guardsmen. The cohortes praetoriae recruited originally in
Italy and the older coloniae in the provinces, though at times legionaries were
transferred to the guard. From the reign of Septimius Severus the transfer of picked
legionaries became the usual method of filling the ranks of the praetorian guard.

The praetorian guard originally served as the backbone of field armies assembled for
campaigns that involved the emperor, one of his relatives or a praefectus praetorio.
Contrary to popular opinion this meant that the Rome based soldiers had a fair
chance of being involved in combat either against the barbarians from across the
borders or rebellious Roman army units. Despite the increase in the establishment
strength of the praetorian cohorts the guards were increasingly complemented by
other formations. In the course of the third century AD the cohortes praetoriae in
the comitatus, the imperial field army, were regularly supplemented by mobile troops
from the legio II Parthica based at Albanum in Italy. Vexillationes of elite legionaries
and auxiliaries from the frontier armies joining these core formations in the imperial
field army were slowly developing into separate units that were permanently
attached to the imperial retinue.

The imperial horse guard

The citizen guardsmen of the praetorian cohorts had their counterpart in the
originally non-citizen horse guards. These consisted in the Julio-Claudian era of
the Germani custodes corporis disbanded after Nero and the later equites singulares
Augusti. Both these units were also known as Batavi after the tribal origin of many
imperial horse guards. Members were usually recruited from the alae and cohortes
equitatae, though at times men were directly recruited. The centuriones
exercitatores or cavalry training officers for the imperial horse guard were however
not drawn from the auxilia, but were selected from the legionary cavalry. The
strength of the horse guard was approximately a thousand troopers, a number
doubled by Septimius Severus. The organisation of the horse guard resembled that
of the cavalry in the auxilia with turmae commanded by decuriones. An
equestrian tribunus functioned as overall commander of the imperial horse guards.

The fleet
The main function of the classis or fleet was to combat piracy and to support the
operations of the other armed services. The imperial navy maintained two larger
fleets based in the Mediterranean with smaller squadrons operating on the North
Sea, Black Sea and the major rivers. Ravenna and Misenum were the main naval
bases in the mare nostrum though ships were regularly detached to other ports.
There existed some dedicated fleet installations along the river Rhine and Danube,
but most were attached to bases of the frontier armies. The ships used by the
imperial navy comprised both oared warships and transports as well as sailing craft
used mainly for logistical support.

The vessels of the Roman navy were not manned by the slave rowers of popular
imagination. All personnel serving in the imperial fleet were classed as soldiers,
regardless of their function. Though the fleet had its own marines, these troops were
used for boarding parties rather than amphibious assaults. The status of the sailors
and marines of the Roman navy is somewhat unclear, though the fleet is generally
regarded as the least prestigious branch of service. The fleet recruited freeborn
citizens and peregrini as well as freedmen. Soldiers that did not possess Roman
citizenship received this privilege after a minimum of 25 years of service.

A ship’s crew, regardless of its size, was organised as a centuria with one officer
responsible for sailing operations and a centurio for the military tasks. Among the
crew were usually also a number of principales and immunes, some of which were
identical to those of the army and some of which were peculiar to the fleet.
Command of fleets was given to equestrian praefecti, those of the fleets based at
Ravenna and Misenum having the largest prestige. The total strength of the Roman
navy is not known with any exactitude, though it was reportedly some 40.000 strong
during the reign of Diocletian. The Ravenna and Misenum fleets were each at least
numerous enough to furnish the required number of men for a new legio.

Naval forces were used to create both auxiliary units, the cohortes
classiariorum and cohortes classicae, and legionary formations, the legiones I and
II Adiutrices. In addition men were also transferred to the auxilia or legiones on an
individual basis. The fleet squadrons in at least the Danubian provinces may have
received direct support from army units, as there is evidence available that a number
of legionary soldiers received training as epibatae or liburnarii for service as marines.

2. The Army of the Dominate

The army of the tetrarchy

The field armies

Under Diocletian the frontier armies bore the brunt of the defence of the empire. The
role of the field armies decreased somewhat as political stability meant that
usurpations were a lesser threat that they had been before. Each of the tetrarchs
had a small sacer comitatus at his disposal. The nucleus of these imperial field
armies was formed by guard units and a select number of permanently attached
detachments from the provincial armies. For large campaigns these formations were
temporarily joined by vexillationes from the frontier forces.

The tetrarchic field armies were made up of a number of different formations.

Detachments from the praetorian guards, both infantry and mounted troops like
the equites promoti, were permanently attached to the retinue of the emperors.
These units were by this date also known as cohortes palatinae. The old equites
singulares Augusti still existed as the imperial horse guard, although these
guardsmen had traded in their name for equites dominorum nostrorum. New guard
units had been created in addition to the old. A mounted schola scutariorum was
probably already part of the imperial guard. The unit of protectores consisted of
promising men being groomed for higher commands. Elite legionary detachments
like the Ioviani and Herculiani drawn from the legio I Iovia
Scythica and legio II Herculia and the lancearii recruited among the legionary light
infantry were permanently attached to the comitatus. Vexillationes of picked
cavalrymen from the frontier units and elite auxilia were also included.

The frontier armies

The reign of Diocletian and his fellow emperors saw a massive increase in the
number of legions. There were 39 legiones in existence in 286, but this number was
almost doubled over the next thirty years. This did not however mean that the total
strength of the army was increased on the same scale. Although the structure and
establishment strength of these new formations were similar to that of earlier units,
some of the tetrarchic legions were formed by combining existing units of the auxilia.
These formations were distributed in pairs among the new, smaller provinces. Some
new auxiliary units were also created, but the overall strength of the auxilia probably
dropped as a result of the formation of legions from auxiliary cohorts.

Recruitment for the enlarged armies proved to be a problem. Not only were old
conscription regulations applied with more severity than before, but several new
measures were introduced to fill the ranks. Sons of serving soldiers and veterans
were now by law required to enlist in the army. The protostasia, a recruitment tax on
landownership, was a novel measure. Landowners were obliged to furnish army
recruits in proportion to the size and yield of their properties. Those owning only
small tracts of land were grouped together and taxed collectively. Not all parts of the
empire were subject to levies of men. In the provinces whose population was
considered to lack the required martial spirit, the recruiting tax was converted into
payments of money known as the aurum tironicum or recruit gold. This money was
used to provide bounties to attract volunteers. Men were also recruited from outside
the empire, either voluntarily or by the incorporation of barbarian POW’s in the army.

The late Roman army

The field armies
The late Roman army contained several different field armies. Some of these, the
so-called praesental armies, were under the direct control of the emperors and were
the successors to the third century sacer comitatus. Other formations were based in
the provinces and served as regional reaction forces. The field army units were
composed of both palatini and comitatenses. There were few, if any, differences
between these classes of troops, though the former carried more prestige. Cavalry
units consisted of vexillationes palatinae and vexillationes comitatenses that
provided a mix of heavy, medium and light cavalry. The legiones palatinae, legiones
comitatenses and the auxilia palatina consisted mostly of heavy infantry, although
some units were also employed as light infantry and archers. The legiones
pseudocomitatenses attached to some field armies were detached formations from
the frontier armies. A new development was the formation of
separate legiones of ballistarii. These formations consisted of artillerymen operating
light torsion guns and crossbows.

Unit organisations and establishment strengths for the late Roman army are difficult
to reconstruct. Legionary detachments had evolved into separate units and were
now termed legio rather than vexillatio. This meant that a legio could compromise
any number between 500 and 5000 men. However 1000 to 1200 soldiers appears to
have been a common establishment strength for many of the smaller legions. The
internal organisation of these new legions is hard to establish. Although the ancient
sources mention centuriae, manipuli and cohortes, the references appear formalistic
and may not reflect actual conditions. The auxilia palatina consisted partly of newly
raised units, but others had evolved from existing auxiliary cohortes. Their strength
and organisation were probably similar to those of military cohorts.
Cavalry vexillationes are likely to have been 500 strong with internal unit
organisation similar to that of the earlier alae. A major break with the past army
organisation was the removal of mounted troops previously attached to infantry
formations. Units in the late Roman army consisted of either horsemen or foot
soldiers, not a mix of both.

Command of the field armies was normally in the hands of senior officers known
as magistri, though minor armies could be commanded by a comes. There were
some minor variations in the titles of the field army commanders but there appears to
have been little difference between the rank and function of a magister
equitum, magister peditum or magister militum. Command of units of any kind was
by now generally in the hands of a tribunus. These tribunes were professional
military officers who had often served as a protector at the imperial court. The tribuni
vacantes were officers that were not directly attached to army formations and served
in similar capacities as the earlier centuriones supernumerarii. The
designation praepositus merely indicated the function of commander rather than an
actual military rank. Centuriones were by this date more commonly referred to
as ordinarii and centenarii. Officers with identical titles served in both cavalry and
infantry units. Optiones received the new title of biarchus. Many other new
designations for officers and NCO’s appear in the sources, but are often difficult to
interpret.

Unit titles in the later Roman army were of a slightly different style than those of their
early imperial counterparts. Although a lot of units retained names derived from unit
numbers, like the Quarti Dalmatae, or their armament, as the Sagittarii Dominici did,
there were a few peculiar late Roman practices. Many formations carried the
designations of seniores, the ‘old ones’ or ‘veterans’, and iuniores, the ‘young ones’
or ‘recruits’. These titles were probably connected to a split-up of the armies among
the sons of Constantine that resulted in small cadre forces being detached from
existing units to form the backbone of newly recruited formations of the same name.
As both types of unit received replacements in an identical
fashion iuniores and seniores alike were soon composed of a similar mix of recruits
and experienced men. Some late Roman army units also carried barbarian tribal
names, but like the titles of earlier auxiliary units these were usually not
representative of the ethnic origin of its soldiers, the majority being of Roman rather
than foreign extraction.

The frontier armies

The frontier forces were entitled limitanei or riparii. These consisted of
infantry legiones, cohortes and numeri and cavalry vexillationes, alae and cunei.
Frontier legiones were generally but not invariably larger formations than those found
in the field armies with a strength and organisation resembling that of the earlier
legions. Many units of the limitanei, both legionary and auxiliary, were divided over a
number of small fortified bases. Often labelled a peasant militia with low fighting
value in modern studies, these troops were in fact professional military units not
significantly worse in calibre from those in the field armies.
The palatini and comitatenses were regularly supplemented by forces drawn from
the frontier armies.

Armour and equipment

Contrary to popular opinion late Roman troops were as heavily protected by armour
as their early imperial predecessors. Although according to the available evidence
the famous “lorica segmentata” was no longer in use after the late third century,
literary and depictional sources indicate a continued general use of scale, mail and
lamellar body armour by both mounted troops and foot soldiers. A padded leather
and linen protective vest known as a thoracomachus was worn beneath metallic
armour. Additional protection was provided by splinted greaves and armguards,
notably in the ranks of the heavy cavalry. Helmet bowls were by this date usually
constructed of several segments. The distinction made in some modern works
between cavalry and infantry types does not appear to reflect ancient practice.
Shields for all troop types were generally of oval or round shape. The unit shield
patterns for many field army formations have been preserved in the Notitia
Dignitatum, apparently with a remarkable degree of reliability.
Late Roman soldiers carried a variety of missile weapons. The introduction of new
names for shafted weapons tends to disguise the fact that there was little essential
difference between early and later imperial military practice. Heavy infantry
continued to use javelins with long iron shanks similar to the earlier pilum. These
could have both pyramidical points for better armour penetration or viciously barbed
heads for use against unarmoured targets. Lighter javelins of different types
remained the normal equipment of the cavalry, the light infantry and the rear ranks of
infantry formations. There may however have been a greater emphasis on longer
range fire power. A genuinely new addition to the armoury was the weighted
throwing dart, the plumbata or martiobarbulus. This gave troops missile weapons
with an improved range, though carrying the penalty of a somewhat decreased
penetration power. Also the more widespread indications for the incorporation of
archers in javelin armed units may point to an increase in the proportion of archers in
late Roman formations.

The sword remained the weapon of choice for close quarter combat, though
thrusting spears, daggers and axes were also employed. From the second century
AD onwards weapons with longer blades had gradually replaced short swords in
infantry service. The change in weapon type does not appear to have been linked to
a drastic alteration in the tactics of the Roman heavy infantry. Troops continued to
fight in close order formations using cut-and-thrust swordplay. Apart from the
appearance of weapons and equipment little had changed from the days of the
Roman republic.

Barbarisation
The late Roman army is often stated to have suffered from barbarisation, a
deterioration of old standards as the result of the recruitment of large numbers of
barbarians, especially Germanic tribesmen, from across the borders of the empire. In
fact the recruitment of barbarians into the ranks of the late Roman army did not take
place in extraordinary numbers. Recent research indicated that even in the auxilia
palatina, formerly considered to be heavily barbarian in composition, only a fifth to a
quarter of soldiers were of barbarian extraction. Many early imperial army units
contained a higher proportion of foreigners or only recently subjected barbarians.
The majority of troops in the late Roman army were therefore of provincial Roman
origin.

Barbarian influence on tactics, equipment and organisation also appears to have

been very limited. The longer swords used by Roman infantry soldiers from the
second century AD were not a sign of changing tactics. The use of the Roman short
swords for stabbing rather than slashing has always been overemphasized in
modern literature. Even the republican legionaries are explicitly described by
Polybius to employ their Spanish swords for slashing as well as thrusting. The longer
blades of late Roman troops were pointed and would have increased their reach in
close quarter battle. The spatha was in fact not a weapon that Romans took over
from Germanic barbarians, but a separate Roman development of earlier Celtic
blades. As most weapons of this type found across the borders were imports from
the Roman empire it appears that the barbarians adopted a Roman weapon rather
than the other way round.
The performance in battle of late Roman troops was not significantly worse than that
of their early imperial counterparts. The Roman army had never been an invincible
war machine. The battle at Adrianople fitted in the list of Cannae, Carrhae, the
Varian disaster, Tapae and countless other defeats. Even poorly armed Judean
rebels destroyed the legio XII in the early stages of the Jewish War. The late Roman
army had more than a fair chance of victory against any barbarian opponent it met.
Persians, Sarmatians and Germans all alike were defeated time and again.

3. The Army of Republican Rome

It is hard to overestimate the importance of warfare in the Roman republic. Waging
war was the most important way of acquiring the reputation and wealth that the
Roman elite needed for a successful political career. Each year new men came
forward to fill the annually elected magistracies, each intent on securing their political
future by achieving military victories that would ensure them the high honour of
a triumphus. Rome was therefore in this period almost continually at war and
gradually extending its power across Italy and the Mediterranean world.

The legions

The Roman army of the middle republic was a militia army. It was composed of a
number of legiones recruited among the citizen body which were levied for specific
campaigns. Under normal circumstances four such legions were under arms which
were assigned two apiece to the two consules. In case more units were needed
these were placed under the command of praetores or pro-magistrates.

The legiones were numbered sequentially with the numbers I to IV being reserved
for the units under the command of the consules. Contrary to imperial practice the
numbers carried by the units were not duplicated. The shifting of the composition of
the army over the years meant that from time to time existing units received a new
numeral. As units were levied for specific campaigns and disbanded when no longer
needed, units did not have the opportunity to develop a distinct identity. The
honorary titles so familiar of the imperial legions only developed during the first
century BC as legions were kept under arms for a prolonged time.

Recruitment
In republican Rome the right to serve in the army was a privilege of the assidui or
propertied citizens. Together these formed the classis or populus. This restriction
was imposed by the fact that the government generally did not take responsibility for
the arming of its fighting men. Citizens were expected to equip themselves at their
own cost with the necessary armour and weaponry when called up for service.
Those not able to meet the property requirements for army service were known as
the capite censi, the headcount, or as proletarii. These poorer citizens were only
enrolled in times of emergency and equipped at state expense. Though the capite
censi usually served as rowers in the navy they were at times incorporated in
the legiones. Extreme measures were taken in the aftermath of Cannae with the
formation of several units composed of volones, freed slave volunteers. Property
qualifications for service in the army were gradually lowered as time went by to
enlarge the potential pool of recruits. Generally the number of volunteers in the army
was limited, though campaigns with lucrative prospects of plunder like those against
Macedonia could attract larger quantities of men eager to serve.

Roman citizens that met the property qualifications were liable for conscription from
the age of seventeen, though repeated legislation against the enlistment of younger
soldiers indicates that recruits could be very young indeed. Up to the age of 46
citizens of means remained under the obligation to serve. The maximum number of
years to be spent in the army was set at sixteen, though this limit was removed in
time of emergency. Gradually however it became the norm to serve six years in
succession before being discharged with reservist obligations. Cavalrymen on the
other hand had to serve ten campaigns before being released.

The cavalry arm of the republican legion was constituted from wealthy citizens drawn
mainly from the ordo equester able to meet the extra expense of providing a horse
and its necessary equipment. Though a few select individuals served with a horse
provided by the state, the so-called equus publicus, most cavalrymen bore the cost
of their mounts themselves. The great financial burden of serving in the cavalry
limited the size of the legionary horse. To some extent this lack of numbers was
made up by the larger contingent of allied and auxiliary cavalry.

Pay at this date was minimal, barely meeting the expenses for equipment, food and
other necessities. Soldiers in the republican army therefore needed other sources of
income. With Roman armies almost continually campaigning abroad the opportunity
for plunder was however great. This helped ensure a continued support for
expansion of the empire.

Legionary armament
The Roman cavalrymen were armed in a similar way to their counterparts in the
Hellenistic armies. Legionary horsemen were equipped with helmet, body armour,
shield, sword and a thrusting spear. The majority of troopers served as shock
cavalry, though there are indications that some men may have served as ferentarii,
light cavalry skirmishers. Legionary light infantrymen were at times intermixed with
the cavalry to bolster its strength.

The legionary infantry were divided in a number of classes with varying equipment
and battlefield duties. The youngest and poorest soldiers served as light infantry
which were known as velites, leves, rorarii or ferentarii. These light infantrymen were
backed up by more heavily armed antesignani. The primary strength of
the legio however resided in its heavy infantry. This was divided in three main
divisions. The first of these were the hastati, the ‘spearmen’. These consisted of
relatively young soldiers and were usually deployed in the first battle line. The
second class were the principes or ‘leaders’. These men constituted the cream of the
army and were normally deployed in the second battle line. The
veteran triarii or pili made up the third class and were either deployed in the third
battle line or left behind to guard the camp.

The legionary light infantrymen were mostly equipped with a parma or buckler, a
number of hastae velitariae or light javelins, a sword and a helmet covered with an
animal pelt. Some may however been armed with a sling. The antesignani used to
support the light troops carried equipment similar to the heavy infantry with pila and
body armour being mentioned in the sources. The hastati, principes and triarii were
equipped with helmet, body armour, greaves, swords and large scuta or shields.
Most men wore a copper alloy pectorale, though the wealthiest legionaries wore
either scale or mail armour or an anatomical cuirass. The men of the first two battle
lines carried heavy javelins called pila, but the usual shaft weapon of the triarii was a
long stabbing spear. Double edged swords were the main weapon used in combat,
the famous gladius Hispaniensis being derived from Spanish examples. Torsion gun
artillery was at times used by the legions in this period, though it may not have been
allocated on a regular basis.

The legion deployed usually in a formation of three battle lines of heavy infantry
protected by a screen of skirmishers. The manipuli would initially deploy with
the centuriae positioned one behind the other for ease of manoeuvre. Gaps were left
between the manipuli but these were closed before engaging the enemy by
the centuriae posteriores moving up to position themselves on the left of
the centuriae priores. Tactics were generally simple consisting mainly of a blunt
frontal attack. First the hastati would engage the enemy, throwing their pila before
charging with their swords. These troops were relieved by the units of
the principes in case of failure. The triarii were used as a last resort, the Latin
expression ad triarios redisse being used to indicate that one was in a desperate
position. Roman commanders confident in the ability of the hastati and principes to
secure victory in battle left the triarii behind to guard the camp. Given the militia
nature of the army at this point and the lack of prolonged and continuous training of
the troops Roman tactics were by necessity predictable. Only when troops were kept
under arms for years at a time could commanders like Scipio Africanus attempt to
introduce more sophisticated tactics.

The organisation
The strength of a legio was variable and depended on the specific needs of a
campaign. The authorised strength of foot varied between some 4200 to over 6000
infantrymen and the establishment strength of the horse varied between 200 and
300 troopers. In a legion of 4200 this was divided in some 1200 each
of velites, hastati and principes and 600 triarii. An increase in the number of
infantrymen did not affect the number of subunits as the strength of these was
merely increased. It was also usual that when the legion’s complement was
strengthened the units of triarii generally received fewer extra men than the other
classes of troops.

A legio was subdivided in thirty manipuli consisting of two centuriae. Command of

the manipulus lay in the hands of the senior centurio commanding the unit on the
right of the formation, the officer of the other centuria acting as his deputy.
The hastati, principes and triarii each had ten such manipuli numbered I to X. The
other infantrymen were attached to these units having no separate organisation. The
strength of the units of triarii was generally only half that of
the hastati and principes Gradually new subdivisions called cohortes were
introduced in the Roman legiones, probably patterned on similar formations of the
Italic allies. In these units one manipulus of hastati, principes and triarii with their
attached light infantrymen were brigaded together. The need for small independent
units to fight against the tribesmen in the mountains of Spain is likely to have been
the stimulus for the creation of these new legionary subdivisions.

Each legio had its own organic cavalry arm. The usual strength of the legionary
horse varied between 200 and 300 cavalrymen. These horsemen were organised
in decuriae of each ten troopers under the command of a decurio,
three decuriae being grouped together in a turma under the overall command of the
senior decurio. Within each decuria a rear rank officer was appointed by its
commander.

The officers
The command of a legio was entrusted to six tribuni militum drawn from the
senatorial class. A minimum of five to ten years prior army service was required
before men were eligible for the post of tribunus militum.
Former praetores and consules as well as young men at the start of their public
careers served as tribunus ensuring that at least part of these officers were
experienced commanders. Part of the tribuni were elected by the popular assembly
and known as comitiati while other officers of this rank termed Rufuli were selected
by the commanders-in-chief. Junior officers known as centuriones were selected by
the tribuni among the more experienced fighting men. Commanding
the manipuli were the centurions called hastatus prior, princips prior and pilus
prior with the hastatus posterior, princeps posterior and pilus posterior personally
selected by the former acting as their deputies. Great prestige was attached to the
post of primus pilus, the senior centurion commanding the first manipulus of triarii.
As senior centurion of the legion this officer was admitted to the councils of the high
command.

The centuriones were assisted in their tasks by a small number of NCO’s. The
republican legionary organisation was however much simpler than the elaborate
imperial system of principales and immunes. An optio served as a rear rank officer
keeping the legionaries in check, a signifer carried the unit’s standard and
a tesserarius was in charge of the watchword. Attached to each manipulus as
military musicians were further a cornicen and tubicen. Contrary to imperial practice
the NCO’s probably earned the same pay as the ordinary soldiers, centurions
themselves at this time only being paid twice the amount of the rank and file.

The fleet
The military power of the Roman state had until the Punic Wars been mainly based
on land. The struggle with Carthago forced the Romans however to become a
maritime power as well. During the First Punic War a large fleet was built from
scratch allegedly using a stranded Carthaginian vessel as a prototype. The standard
type of warship was the quinqueremis with five rowers on three banks. The lack of
skill of the Roman sailors meant that the traditional manner of naval combat with
manoeuvring galleys trying to ram their opponents was abandoned for a new
approach. Roman vessels were equipped with a corvus or raven, a movable
boarding bridge which enabled the Romans to turn naval battles in engagements
between marines rather than ships. This new invention enabled the Romans to score
some spectacular successes against the Carthaginian fleet, but the added weight of
the boarding bridge made their vessels less seaworthy resulting in heavy losses due
to storms.

The achievement of military superiority on sea during the Punic Wars enabled the
Romans to land their land forces on the coast of North Africa to bring the war to their
enemy. The naval supremacy gained by the Roman fleet also resulted in Carthago,
formerly relying on its sea power, choosing to fight the Second Punic War on land
instead. With the demise of Carthago as a leading naval threat the Romans lost
interest in maintaining a powerful fleet themselves. With the seas no longer patrolled
by warships this led to an increase in piracy in the Mediterranean.

The allies
The citizen troops serving in the legiones were supplemented by troops drawn from
allied and conquered communities, the socii. Another term in general use for
the socii was auxilia, supporting troops, or cohortes alariae. These forces were
divided in several types but the most important were the Italic socii or allies. Among
these the socii nominis Latinis, the allies of the Latin league, were the most
prominent. Generally the majority of these Italic allies were staunchly loyal to the
Roman cause. Even after the series of disastrous defeats inflicted by Hannibal only a
minority of Italic communities defected to the enemy. The Italic socii were
occasionally rewarded for their services by the granting of Latin rights or Roman
citizenship. The increasing rarity of these grants in the second century BC was one
of the main causes of the Social War fought between Rome and her Italic allies.

The Italic allies were organised in alae sociorum, one of which was attached to each
Roman legion. The name of ala or wing was derived from their usual position on the
flanks of the citizen troops. As with the legions the establishment strength of these
units was variable and adjusted to the requirements of the envisaged campaigns.
Few allied communities were large enough to supply a full sized ala sociorum and
therefore these units were usually composed of a number of contingents supplied by
various allies. These contingents were organised in cohortes with a praetor drawn
from the upper class in command. The allied praetores were however subordinated
to Roman praefecti sociorum within the organisation of the alae.

The exact structure of the allied alae is somewhat unclear. However most modern
authorities assume that the units of the socii were generally similar in composition to
the citizen troops with a mix of both light and heavy infantrymen and cavalrymen
drawn from the same community. However some passages in the sources mention
allied contingents consisting solely of skirmishers. This may indicate that there was
no generalised pattern and the type as well as number of forces supplied varied for
each ally. A major difference between the legions and the alae sociorum was in the
number of horsemen attached. Generally the allied formations counted double or
triple the number of cavalry attached to the citizen units.

Among the Italic allies one fifth of the infantry and a third part of the horse were
selected for service as pedites – and equites extraordinarii. This elite corps served
as a bodyguard to the Roman generals and formed the vanguard on the march.
These troops were organised in their own cohortes. If later imperial practice is a
reliable guide, soldiers were individually picked for service in these guard formations.
As a citizen counterpart to the allied extraordinarii some Roman commanders formed
a cohors praetoria of picked legionary troops.

In addition to the ground forces supplied by the Italic allies, the so-called socii
navales, the naval allies, were responsible for furnishing Rome with ships and crews.
After the Punic Wars Rome increasingly relied on such allies to supply the vessels
and men whenever the formation of a fleet was required. The warships provided by
the allies were of the current types such as triremes and quinqueremes.

Next to the Italic allies existed other supplementary forces. Some of these were true
allies bound by treaty obligations while others served as mercenaries. The numbers
and type of these forces varied as much as their origin. Many were employed only in
local campaigns, but Numidian light cavalry, Balearic slingers, Cretan archers, Gallic
and Thracian horsemen regularly served in Roman armies far from their home
countries. To some extent these troops provided complementary fighting skills to
those of the Roman legions and their Italic allies.

4. The Roman army of the late republic

The army of the late republic

The Roman army of the late republic is often connected to the so-called Marian army
reforms. In fact radical reforms of the army structure were few. What novel measures
were taken, were moreover in fact the work of other generals than Gaius Marius.
One of the more current misconceptions regarding the Roman army in the later
republican era concerns the introduction of a professional army recruited from
volunteers to replace the militia army composed of conscripts. Conscription was not
ended by the fact that Marius accepted volunteers from the capite censi. Draftees
rather than volunteers continued to provide the bulk of legionary recruits. Neither is
there much actual evidence for wide ranging organisational and tactical reforms by
the great general. The cohors appears to have been incorporated in the regular
organisation well before the days of Marius. Although gladiatorial trainers were
employed as an emergency measure by Rutilius Rufus after the defeats inflicted on
the Romans by the Cimbri and Teutones there are no indications available that this
entailed a drastic improvement in training standards. It is also very doubtful that
instructors of this unsuitable background continued to be employed after the
emergency situation had passed. The light infantry velites were not abolished by
Marius, merely being equipped with different shields and continuing to serve in the
wars of Sulla against Mithridates. One measure however is very closely associated
with Marius. This general reduced the size of the legion’s baggage train by requiring
his soldiers to carry much of their equipment themselves. This resulted in the heavily
laden legionaries being nicknamed muli Mariani or Marius’s mules.

The command structure of the Roman army underwent considerable changes in the
late republic. The role of the consules as the primary commanders of Rome’s legions
diminished, finally being ended by the Sullan reforms of the constitution. In their
stead proconsuls and commanders granted extraordinary powers were now the most
important army leaders. The restriction on the maximum number of legions under the
command of a single general was lifted. Armies could now be made up of up to
several dozens of legions. The nature of the army also changed with soldiers being
loyal to their commanders rather than the Roman state itself. The fact that
campaigns in this period tended to be more prolonged and the securing of discharge
benefits by the personal influence of the generals attached the soldiers much more
closely to their leaders.

The legions
The legiones provided the citizen troops of the Roman army. As a result of the
expansion of the empire the number of units under arms at any given moment had
risen since the middle republic. Some of these units remained in service for longer
periods, discharging soldiers who had served their time and accepting new recruits
in their place. These semi-permanent units began gradually to develop their own
distinctive identity, a process accelerated by the prolonged Gallic campaigns of
Caesar and the civil wars that followed it. With different parties in the civil wars each
levying their own armies, legionary numerals started to be duplicated. Legions
started to adopt honorary cognomina and acquire particular symbols and signs.
Some commanders valued this esprit de corps of their legiones to such an extent
that they preferred to levy new units rather than dilute their veteran formations with
the influx of new men.

Legionary recruitment
Contrary to popular opinion the majority of legionary soldiers in this period remained
levied conscripts rather than volunteers drawn from the capite censi. The property
qualifications that had already been lowered several times in the previous decades
however appear to have been waived altogether. To enlarge the legionary
strength legiones vernaculae were raised from provincials rather than Roman
citizens on several occasions, notably during the civil wars of the first century BC.

Men enlisted in the army now generally had to serve for longer periods of time and
were often from an impoverished agrarian background. Roman generals interested
in gaining the loyalty of the troops were therefore keen on securing special discharge
benefits for their men. This often took the form of distribution of land to time served
soldiers. For this purpose land was on several occasions confiscated on a huge
scale, both in Italy as well as the provinces.

Service conditions were greatly improved during the civil wars. Previously pay had
barely covered expenses and soldiers gained only by the opportunities for plunder.
The fighting between the various civil war parties enabled the loyalty of the troops to
be converted in wealth. Commanders anxious to attach the legionaries to their cause
distributed generous bounties known as donativa to their troops on a regular basis.
Caesar did much to enlarge his popularity by doubling the standard rate of pay and
providing silvered and gilded equipment to his men. The provision of weaponry and
equipment by the Roman government and commanders to the troops remained an
exception to the rule, the soldiers still being expected to equip themselves at their
own expense.

Legionary organisation
The composition of the legio in the late republic was different from the earlier
formations. The light infantry velites disappear from the records after the battles of
Sulla in Asia Minor, their role being taken over by a mix of legionary antesignani and
auxiliary skirmishers. The units of the triarii were by now brought up to the same
strength as those of the hastati and principes and by this date carried the pilum in
place of the thrusting spear.
Ten cohortes combining manipuli of hastati, principes and pili with the same number
had become part of the regular legionary organisation. The battle formation of the
legion also changed. The triple battle lines of ten manipuli had either been replaced
or supplemented by a new formation with four cohortes in the first and
three cohortes each in the other two battle lines. This new deployment meant that
the legion now had twelve rather than ten manipuli available for action in the front
line.

The old legionary cavalry recruited from the equites Romani disappeared from the
legionary organisation at some point in the first century BC. This may have left
the legio without an integral cavalry arm. However if speculatores in this period were
mounted troops as their imperial counterparts certainly were, a very small number of
legionaries may have been cavalrymen. The apparent lack of substantial citizen
cavalry was made good by recruiting large numbers of barbarian and provincial
horsemen. The Bellum Gallicum relates of one interesting occasion when Caesar
had the entire legio X mounted on horses from the auxiliary troopers to serve as a
reliable cavalry guard during a meeting with the German chieftain Ariovistus.

In the civil wars commanders spent much effort in the formation of loyal elite units.
This was partly achieved by employing foreign bodyguards from barbarians with a
high reputation for loyalty and devotion to duty. Hispanic, Gallic and German
horsemen served widely as personal guards. However picked citizen troops also
played an important role. Caesar established the legio X Equestris as his favourite
unit while other commanders selected legionary soldiers for service in cohortes
praetoriae or bodies of speculatores. The antesignani were another elite corps
picked from the bravest legionaries and employed in a variety of roles including light
infantry skirmishing as well as spearheading assaults.

Legionary officers
There were some changes in the structure of the legionary officer corps compared to
the legions of the middle republic. The status and remuneration of the centuriones in
the Roman army was significantly raised in the late republican period. This was in
recognition of their importance to the army. The pay raise for the centurions may well
have been accompanied by an increase in pay to the non-commissioned officers
which would eventually emerge as the principales of the imperial army.
Legionary tribuni which had previously included men of great experience, were by
this date often young and lacking in experience. This resulted in the command
of legiones being given to legati appointed by the army commander rather than to
the senior tribunus. These legati had however not yet developed in the similarly
named legionary commanders of the imperial army as they were not attached to
particular units and regularly shifted commands.

The auxilia
After the Social War waged against the Italic allies Roman citizenship was granted to
all of these below the river Po. This meant that Italic soldiers were now directly
recruited in the legiones rather than serving in separate alae sociorum. Auxiliary
forces from outside Italy were however employed on a large scale. Many of these
forces were raised for specific campaigns and disbanded as soon as their services
were no longer needed. Only a minority of these units, notably cavalry, achieved a
semi-permanent status.

Part of the auxiliary forces levied for service in the Roman army were organised on
the Roman pattern in cohortes and alae of some 500 men. Command of these units
was partially entrusted to nobles from the communities that supplied the troops,
though legionary centuriones and equestrian officers were also employed.
Equipment and tactics of the auxiliaries were for a large part those of their native
regions. Some units however were equipped and trained according to Roman
standards. A peculiar feature was the formation of some cavalry formations as more
or less private armies of retainers by Roman officers, the ala Scaevae being an
example.

Little is known of the remuneration and other service conditions of the auxiliary
forces. During earlier times allies received upkeep from the Roman state but no
regular pay was provided. Other troops though are described as mercenaries in the
sources indicating that at least some auxilia were paid for their services. To a limited
extent auxiliary soldiers with good service records were granted Roman citizenship.
However these grants were made to individuals and were not a regular occurrence.
Only after the reign of the emperor Claudius would time served soldiers in
the auxilia receive citizenship on a regular basis.

Page Navigation
  Introduction
 Types of Auxilia Units
 Ranged Auxilia Units
 Infantry Auxilia
 Cavalry Auxilia
 Auxilia Deployment (Table)
The Roman auxilia consisted of non-citizens. In the first century CE, around
90% of the population of the Roman Empire were not citizens of Rome. This
meant the auxilia were critical in expanding and defending Rome's territories.
The auxilia were established by Augustus when the principate was founded, in
roughly 30 BCE. By the end of the second century CE, the auxilia outnumbered
the legionaries.

24 CE 130 CE 210 CE

Legions 125,000 155,000 182,000

Auxiliaries 125,000 218,000 250,000

Praetorian Guard 5,000 8,000 15,000

Total Soldiers 255,000 381,000 447,000

If a soldier joined the auxilia, he would not be stationed in the province of his
birth. This meant that if there was a rebellion in a province, the soldier would
not sympathize with the rebellers and would not defect.

The Roman auxilia was an attractive career choice for many people in Rome's
provinces. It provided a steady income of 750 sestertii (150 sestertii less than
legionaries), for people coming from the poorer parts of the Roman Empire, this
was a massive boost to their income. On top of this income, on retirement, he
would receive a pension as well as full Roman citizenship after his twenty-five
years of service.
Regiments of auxilia were structured the same as a Roman cohort (480 men).
However, they operated on their own and not part of a larger collection of
cohorts like the legions. There were two main types of regiments: cavalry known
as the 'alae' and the infantry referred to as the 'cohortes'.

Types of Roman Auxiliary Units

Unit Name Type No. of Soldiers

Ala quingenaria Cavalry 480

Ala milliaria Cavalry 720

Cohors quingenaria Infantry 480

Cohors milliaria Infantry 800

Cohors equitata quingenaria Infantry & Cavalry 600 (480/120)

Cohors equitata milliaria Infantry & Cavalry 1040 (800/240)

However, it is not so simple to divide the auxilia into predetermined units. The
Roman auxilia were specialist units diverse in their nature.

Ranged Auxilia Units

A large proportion of the Roman army's ranged units belonged to the auxilia. By
the end of the second century CE, archers made up 18,000 of the 180,000
auxilia forces (10%). The Greek island of Crete boasted some of the best
archers in the ancient world and contributed a substantial number of soldiers to
the Roman auxilia. Thrace and Syria also provided a significant number of
ranged units to the Roman military. In the second century CE, there were thirty-
two units of archers. Thirteen of these came from Syria, five from Anatolia, one
from Crete and seven from other provinces.

Just as there were provinces prolific for their archers, it was the Balearic Islands
which provided the best slingers.

Auxilia Infantry (Cohortes)

The auxilia infantry was very similar to the legionary infantry. Split into six
centuries of eighty men each; they also received almost identical weapons,
armor, and training. The infantry was equipped with helmets, mail armor and a
sword (gladius). The cohortes would have been deployed on the flanks of the
Roman legionary infantry.

Auxilia Cavalry (Alae)

The cavalry of the auxilia, the alae, were elite units. These units were organized
into squadrons of thirty cavalrymen. They received extensive training in
complicated maneuvers and also received around 20% more pay than the
auxilia infantry. The auxilia cavalry was very important to the Roman army as
the legions had limited cavalry capacity. These cavalry units were usually
heavily armored in mail armor and would either carry a long Roman sword
(spathe) or a spear (hasta).

In addition to the alae the 'equites cataphractarii' were extremely heavy cavalry.
These units were based on the Parthian cataphracts. These units were capable
of smashing into enemy infantry and completely destroying their formation often
causing them to flee.

There would have also been a large contingent of light cavalry. These units
were often recruited from northern Africa who possessed a large base of
talented riders. They would only be equipped with a small round shield, and a
spear (hasta). These units were incredibly quick and agile, allowing them to
move around the battlefield easily. They would be useful in gathering
intelligence, pre-battle skirmishes and chasing down the fleeing enemy.

Beyond conventional cavalry units, during the second and third centuries CE,
there is evidence of camels being ridden into battle.

Auxilia Deployment (130 CE)

Auxilia Auxilia Total
Province Modern Day Equivalent Infantry Cavalry Auxilia

Britannia England and Wales 25,500 10,500 36,000

Germania Germany 18,000 7,500 25,500

Raetia and Switzerland and Austria 11,000 5,000 16,000

Noricum

Pannonia Hungary, Slovenia and 11,000 8,000 19,000

Croatia

Moesia Serbia, Bulgaria 11,000 5,500 16,500

Dacia Romania 18,000 7,500 25,500

 Auxilia Auxilia Total
Province Modern Day Equivalent Infantry Cavalry Auxilia

Cappadocia Turkey 8,000 3,500 11,500

Syria Syria 21,500 10,000 31,500

Aegyptus Egypt 5,000 3,000 8,000

Maurentania Algeria and Tunisia 15,000 8,000 23,000

Total 144,000 68,500 212,000