The auxiliary regiments naturally did not fare so well. The small detachments drafted off for service in the field army probably soon lost their identity, and the castella, which contained the regimental head-quarters, must have often been taken and destroyed. Still, as the appendix shows, over fifty regiments survived long enough to be included in the Notitia. Naturally the chances of surviving had varied on different frontiers. The section of the Notitia which deals with the northern frontier of Britain contains so many names of pre-Diocletianic regiments that it has sometimes been thought to represent the earliest stratum in the whole work. There seems, however, no reason to doubt that the original garrison, although in attenuated numbers, succeeded in maintaining itself until well into the fourth century. We know from archaeological evidence that even the mile-castles were not abandoned until the reign of Constantine.[436] An almost equally large proportion of old regiments is present in the garrison of Cappadocia, which had been spared the full force of the Persian attack.[437] In Egypt, too, most of the old regiments still survive, although they are largely outnumbered by recent formations.[438] The garrison of this important corn-producing province, more essential than ever since the foundation of Constantinople, had evidently been increased to guard against renewed attacks from the Blemmyes on the Upper Nile, who had raided it successfully in the third century. The Rhine frontier, on the other hand, seems to have been swept of its old garrison from end to end. Two of its legions have disappeared, and the other two, which are included in the field army, probably only survive thanks to their names being preserved by detachments which were absent when the fortresses were stormed.[439] It is not until we reach Raetia and the protection of the Upper Danube that any of the old auxiliary regiments appear. On the Middle and Lower Danube, however, the scene of repeated invasions and civil wars during the third century, few of the old troops survived. The struggle was probably a long one: we know from epigraphical evidence that several forts were still holding out towards the end of the century, and excavation may show that many barbarian raids retired without doing any serious damage. But the attack was constantly renewed, and it is not surprising to find that three new cavalry formations have replaced the Cohors Hemesenorum at Intercisa,[440] and that detachments of Equites Dalmatae are now responsible for practically the whole stretch of frontier between Belgrade and Buda-Pesth.[441] Only the Cohors I Thracum C. R. and the Cohors III Alpinorum, the latter of the old Dalmatian army, remain to remind us of the corps which defended this frontier in the second century.[442] On the Lower Danube, where the Goths had crossed in force, and in the oriental provinces which had felt the heavy hand of Persian invader and Palmyrene usurper, we are only greeted by similar survivals.[443] The section dealing with Cyrenaica is lost, so that we know as little of its garrison now as in the previous period. In Africa the frontier had been reorganized in a number of small districts, each under an officer styled praepositus limitis, and although we have a list of these districts, we are not told by what troops they were guarded.[444] Only for Tingitana are we given a slightly fuller schedule in which a few old names appear.[445]
The isolation of these remnants of the old imperial army among the flood of Teutonic and other barbarian immigrants shows that the new régime inaugurated by Diocletian was foredoomed to failure. The Empire had trusted to a professional army recruited from a comparatively small section of its inhabitants, and when this army succumbed to the strain of civil war and foreign invasion, and the old recruiting-grounds were wasted, few of the provinces of the interior, which for nearly two centuries had practically ceased to furnish soldiers, held any reserve of military material. By admitting this and calling upon the barbarian to occupy and defend the wasted frontier lands, the civilization of the ancient world showed that it had lost the vitality which might have assimilated these new elements as Gaul, Spaniard, and African had been assimilated in the past. A succession of able rulers and the overpowering prestige of the past kept the framework intact for a century after Diocletian’s death. Then when the final catastrophe came, and the Western provinces sank into the Dark Ages, a national revival headed by the still virile races of Asia Minor saved the once despised provinces of the East from being involved in a common ruin. It is with Zeno the Isaurian, not with Diocletian, that the true renascence of the Empire begins.
But the auxiliary regiments which survived into the fourth century need not only suggest to us, by the smallness of their numbers and their isolation among their barbarian comrades, the nearness of the end. The reflection that many of these regiments had held the position assigned to them and preserved a continuous military record for over three hundred years may serve also to remind us of the greatness of the services rendered by the army of the Empire to the cause of civilization.
FOOTNOTES:
[414] For the feelings of legionaries and Praetorians towards one another cf. Tac. Hist. ii. 21 ‘illi ut segnem et desidem et circo ac theatris corruptum militem, hi peregrinum et externum increpabant’.
[415] Dio, lxxiv. 2.
[416] See Liebenam, s.v. Equites Singulares, in Pauly-Wissowa. Cf. Herodian iii. 13, 4.
[417] Herodian viii. 5, 8; Hist. Aug. Vit. Caracalli, 2; Dio, lv. 24.
[418] viii. 20996. He held this post between the command of an Urban and that of a Praetorian Cohort.