Equestrian Officers under the Principate

On this metope from Adamklissi a senior Roman officer is shown riding down a barbarian. Although the relief is quite badly eroded, it is still possible to make out the officer's muscled cuirass, decorative pteruges and flowing cloak. This stone may possibly depict Trajan himself.

Under the Republic there had been very few opportunities for equestrians to rise to positions of authority in the army or provinces. This was all to change under the Principate, when Augustus and his successors created an enormous range of posts for members of the order. This not only provided the Emperor with a far greater number of representatives than the Senate alone could have provided, but it helped to secure the support of the knights for the new regime. Membership of the order was open to all citizens possessing the required value of property and, as the franchise was extended to a growing number of provincials, over time the aristocratic families of much of the Empire became equestrians and were able to have public careers.

There were far more equestrians than senators, and they were able to hold a wider variety of posts in the army or government. As a result, there was no single equestrian career pattern in the same way that there was a senatorial career. It is worth considering the various posts open to equestrians.

Auxiliary commanders

With the formation of the regular auxilia as infantry cohorts or cavalry alae, several hundred posts came into being. A few cavalry alae are known to have been led by former legionary centurions in the very early days of the Principate, but this practice was soon abandoned. Otherwise all auxiliary units were commanded by equestrians. The commanding officers of quingenary cohorts and alae were known as prefects (praefecti). Milliary units, and also cohorts bearing the title avium Romano- rum, were led by tribunes. (The cohortes civium Romanorum had originally been raised by Augustus from freed slaves during the military crises of At) 6 and 9. Slaves automatically received citizenship on manumission, but the Emperor had not wanted these men to serve in the legions. After the original recruits had been discharged the units became ordinary auxiliary cohorts, recruited from non-citizens even though they retained their titles.)

Auxiliary units often acted independently, giving their commanders considerable freedom and opportunities to display their initiative. Garrison commanders were often the most senior representative of Roman power for some distance around and as a result might become involved in many aspects of local administration.

Legionary officers

There were five equestrian tribuni angusticlavii in each legion, performing a variety of staff functions. They might also be appointed to command sizeable detachments (vexillations) of soldiers sent to undertake a project or join a field army. Each legion also had a camp prefect who was a member of the equestrian order, save in cases where more than one unit occupied the same fortress in which case there was only one post per camp. We also hear of equestrians who were directly commissioned as legionary centurions and followed a career within this grade.

Troops in Rome

The loyalty of the military and para-military units in Rome was of fundamental importance to any emperor. Rather than entrust command of such units to senators who might easily see themselves as rivals, they were officered by equestrians. Each cohort of the praetorian guard was commanded by a tribune. With only a few short-lived exceptions, the guard as a whole was led by two praetorian prefects, since few emperors were willing to grant this much power to a single man, even if he were only an equestrian. The command structure of the urban cohorts and the vigiles was similar, though each had only one prefect and both he and the tribunes ranked below their praetorian counterparts.

Equestrian provinces

Augustus established some provinces to which he appointed equestrian governors. With the one exception of Egypt, these were smaller areas than the provinces given to senatorial legates. They were not usually frontier provinces and, although some were garrisoned by auxiliary units, none contained legions. One example was Judaea, although after the rebellion under Nero in ad 66 this was felt to require a legionary garrison and was turned into a senatorial legateship. Equestrian governors were at first known as prefects, but this title was changed to procurator before the middle of the 1st century ad.

For much of the Principate Egypt was not faced with significant external threats. However, its population was sometimes unruly and a garrison of two legions was maintained, which was concentrated outside Alexandria, a frequent source of unrest. A highly organized agricultural system based around the annual inundation of the Nile produced a massive agricultural surplus, so that in time Egypt came to supply a high proportion of the grain consumed by Italy and Rome itself. Augustus appointed an equestrian prefect to govern this important province, and forbade any senator from even visiting Egypt without express permission. Even so, the first prefect, Cornelius Gallus, committed suicide when accused of treason following his excessive celebration of his own military achievements.

Uniquely, a legion stationed in Egypt had neither a legatus not a tribunus laticlavius. Instead it was commanded by an equestrian praefectus legionis, who performed exactly the same role as his senatorial counterpart.

Equestrian careers

Equestrians who sought military posts included men born into equestrian families as well as those who had been admitted to the Order at a later stage of their life. A legionary primus pilus, most probably at least in his 40s, normally became an equestrian after his year in the post and could go on to hold senior positions. Other men entered the Order at various ages as they acquired sufficient wealth. Felix, who became procurator of Judaea under Claudius, was one of the Emperor’s freed slaves. Equestrians therefore entered the army at all sort of ages and with varied ambitions.

The most common career for a man born into an equestrian family was the ‘three posts’ (tres militiae):

(i) Prefect of an auxiliary infantry cohort.

(ii) Tribunus angusticlavius in a legion.

(iii) Prefect of a cavalry ala.

The Emperor Claudius decided to increase the status of the legionary tribunate, and for a while made this the third, most senior position, but the practice was unpopular and soon abandoned. A cavalry prefect was usually allowed much more independence than a staff officer with a legion and there was a degree of glamour associated with commanding horsemen, even if these were not citizens. There was also the simple fact that the army required more legionary tribunes than it did prefects of alae, so that even in normal circumstances some tribunes were unable to make the next step. In the 2nd century, probably under Hadrian, the career pattern was refined still further and a fourth post created, as commander of a milliary ala. There were never more than a dozen or so of these prestigious units in existence, so that such commands were reserved for the ablest, or best-connected, officers.

Two standard-bearers from Adamklissi depicted in undress uniform, without either armour or helmets. Each carries a square vexillum flag. Unlike many of the legionaries on Trajan’s Column who have thick beards, the soldiers on the Tropaeum Traiani are invariably shown cleanshaven.

A tombstone from Bonn dating to the middle of the 1st century ad, commemorating the cavalryman Vonatorix, son of Duca He died aged 45 after 17 years ’ service in the Ala Longiniana. Vonatorix is shown bare headed but wearing scale armour and wielding a spear. He has a long spatha sword suspended on his right hip.

Unlike ordinary soldiers, who frequently include their age and length of service on their monuments, equestrians rarely mention such things unless they died whilst actually serving in a post. Such as it is, the evidence seems to suggest that many, perhaps most, men from equestrian families began their military careers at the age of 30 and served from three to four years in each post. These men had already served as local magistrates before entering the army and some would return to such posts after one or more military appointments. Other men spent far longer with the army, and might serve in several different appointments at each level, although in most cases such moves were to a unit in another province. Former chief centurions (a group known collectively as primi pilares) who had been admitted to the Order rarely became auxiliary commanders after the early 1st century ad. Many went on to serve as camp prefects, to posts with the Roman units, and appointments as procurators.

Patronage was as important in an equestrian as a senatorial career. Pliny, whilst serving as legatus Augusti in Bithynia, wrote to Trajan recommending a certain Nymphidius Lupus, son of a former primus pilus who had entered the equestrian order and been serving as an auxiliary prefect when Pliny had been a tribunus laticlavius some years before. Lupus had already completed a term as a praefedus cohortis and evidently hoped for a further position.

It was probably patronage that allowed one Publius Aelius Tiro to command a cohort at the age of 14. It is hard to know whether this post was purely nominal, allowing the youth to draw the pay and gain the prestige without actually spending time with the unit. Men who lacked such influential patrons had far more difficulty. The future Emperor Pertinax tried and failed to gain a commission as a legionary centurion in his youth. It was not until his mid-30s that he was made prefect of an auxiliary cohort instead. In the event he proved a very capable soldier, serving in increasingly senior positions until he was enrolled in the Senate by Marcus Aurelius. Other men, perhaps finding it impossible to advance in the normal way, abandoned the formally equestrian posts and were transferred into the legionary centurionate. The most prestigious positions, commands in the units in Rome, and especially provincial commands, were reserved for especially favoured men.

The tombstone of Longinus Sdapeze from Colchester dates to a little later than that of Vonatorix (opposite) and has the common motif of the horseman trampling an unarmoured - and often naked - barbarian warrior. This man may have adopted or been given the common army name of Longinus when he joined the army in addition to his own tribal name of Sdapeze He served for 15 years and died at the age of 40. Lke Vonatorix he wears scale armour, but in his case has no sword visible and probably wore his on the left.