The Auxilia of the Roman Imperial Army

by George Leonard Cheesman

The previous discussion of the methods by which the auxilia were recruited has dealt only with the private soldiers, and, as a natural corollary, with such officers as were promoted from the ranks. To the position of praefectus, however, the private soldier could not normally aspire, and he attained it, if at all, only under exceptionally favourable circumstances.[283] Normally, the commanding officers of the auxiliary regiments were drawn from an entirely different social stratum to the men, and although the method of their appointment varied and the area from which they were drawn shifted its boundaries at different periods, these changes did not follow the same lines as those which we have been tracing in connexion with the recruiting of the rank and file.

The auxiliary commands are familiar to all students of the Roman Empire from inscriptions of men who went through the equestrian career, the first stage of which was formed by the posts of praefectus cohortis, tribunus legionis, and praefectus alae. It has, however, been pointed out by von Domaszewski[284] that this system was not established until the middle of the first century. Under Augustus and Tiberius, not only was the relative rank of these posts still undetermined, but they were filled in many cases not by young men beginning the equestrian cursus, but by veteran centurions from the legions, especially the primipili. We have noticed this system in the army of Caesar, so that here, as elsewhere, Augustus was continuing a republican practice. The following inscriptions,[285] which are both of early date, give typical careers of this character.

1. C. Pompullius C. f. Hor(atia) prim(us) pil(us), trib(unus) mil(itum), praef(ectus) eq(uitum).

2. M. Vergilio M. f. Ter(etina) Gallo Lusio prim(o) pil(o) leg(ionis) XI, praef(ecto) coh(ortis) Ubiorum peditum et equitum, donato hastis puris duabus et coronis aureis ab Divo Augusto et Ti: Caesare Augusto, &c.

This system is heartily commended by von Domaszewski, on the ground that the auxilia were thus commanded by more skilful officers, and were more under Roman (i.e. Italian) control than was the case in the second century.[286] The assertion, however, seems far too sweeping, since by no means all the auxiliary regiments were commanded by men of this class; there were, on the contrary, many praefecti at this period who came neither from Italy nor even the more Romanized provinces. The Histories of Tacitus show clearly that at the end of the pre-Flavian period a number of auxiliary regiments, particularly those drawn from the more independent border tribes, were commanded by their own chiefs. This practice had not sprung up during the reign of Nero, but was a natural consequence of the development of these corps from contingents supplied by states nominally ‘in alliance’ with Rome.[287] The eight Batavian cohorts who play such an important rôle in the rebellion of 69 were so commanded,[288] as well as an ala of the same tribe.[289] Iulius Civilis himself was a praefectus cohortis,[290] and two Treveri, Alpinius Montanus and Iulius Classicus, commanded a cohort and ala respectively.[291] All these officers, as their names show, had doubtless received the franchise, but they were employed in their capacity as tribal chiefs, not as Roman citizens, and are to be distinguished from the praefecti, who were drawn at this period from the Romanized districts of Spain and from Gallia Narbonensis. It is chiefly as commanders of cohorts that officers of this type appear, since many of the alae dated back, as we have seen, to the period of the civil wars, and had long lost their original character as tribal regiments. This explains the fact that among Italian officers of this period, the title praefectus alae or praefectus equitum appears far more frequently than praefectus cohortis, although the cohorts were of course more numerous than the alae.

During the first half of the first century, therefore, we have a system which differs widely from that revealed by the equestrian cursus honorum. The establishment of the equestrian monopoly of the auxiliary commands was, in fact, only completed by a series of reforms carried out during the period which began with the administrative activity of Claudius, and ended with the reorganization of the army by Vespasian after the disastrous Civil War of 69.

The first of these changes was that the praefecti ceased to be drawn as before from among the veteran centurions of the legions. Early in the reign of Claudius the post of praefectus alae disappeared from the career of the primipili, who were promoted henceforward to the tribunate of one of the cohorts of Household Troops at Rome.[292] Centurions of lower rank were still advanced to the command of cohorts both in this and the succeeding periods, but such cases are very rare.[293] A trace of the old connexion between the legionary officers and the militia equestris still survives, however, in the regular use of a centurion as praepositus cohortis—that is to say, as temporary commander in case of the death or absence of a praefectus.[294] The numeri, too, were often placed in charge of an ex-centurion bearing this title, an arrangement which was probably called for by the intractable character of these barbarian irregulars.[295]

The employment of tribal chiefs as praefecti also became less frequent, as the auxiliary regiments, transferred from one province to another, and recruited from different nationalities, gradually lost their original character. The mutinous officers of the Rhine army, who were doubtless cashiered by Vespasian, were probably the last examples of praefecti drawn from this class.

Lastly, the respective rank of the different posts in the militia equestris was finally determined; and the order praefectus cohortis—tribunus legionis—praefectus alae is hardly ever varied after 70, except that the tribunate of a cohors miliaria sometimes appears in the second place.[296]

The result of these changes was that henceforward the auxiliary officers were practically all of one type, men of equestrian rank entering upon what was now the accustomed cursus honorum of their class. That this system was not universally adopted at an earlier date is not surprising. The equestrian praefecti were young men directly appointed by the emperor, without any previous military training; before the auxilia could be entrusted to their charge a certain advance in civilization and tractability had to be made by the provincials, and the veteran centurions and tribal chiefs of the Augustan system were more fitted to deal with the men who composed the auxiliary levies during the first hundred years of the Empire. As it was, these regiments contained in the second century far fewer representatives of the governing class than the native corps in our own Indian army. With the exception of the praefectus, who himself was not necessarily an Italian, the officers—that is, the centurions and decurions—were practically all, as we have seen, promoted from the ranks. But to the Roman Empire, in which rulers and ruled, never separated by any deep racial or religious gulf, were gradually made closer akin by the bond of a common civilization, our rule in India affords in this respect no real parallel.