But the very fact that so many of the old corps still figure on the army list tempts us to consider the circumstances under which they survived and to take a brief survey of the changed conditions under which they continued their existence. It is fortunate that for the history of the Roman army during the fourth century we possess two authorities of considerable merit, the historian Ammianus Marcellinus and the _Notitia Dignitatum_. Ammianus, himself a soldier, is practically the first historian of the Empire since Josephus to give us a first-hand account of military operations.[421] The _Notitia Dignitatum_ purports to give us, what we do not possess for any earlier period, a complete list of the regiments composing the imperial army. It is true that this list appears to be a compilation drawing from evidence of very different dates, but there can be no doubt that it represents for most provinces the general state of things prevailing in the fourth century. The most significant fact which strikes us in these authorities is the barbaric character of both troops and officers. The majority of the officers mentioned by Ammianus, even those of highest rank, are of Teutonic origin, many being drawn even from the Franks, who are usually reckoned among the more uncivilized of the Empire’s assailants. The same picture is presented by the _Notitia_. Corps which must at any rate have been originally raised from barbarian tribes, who normally dwelt beyond the frontier, abound among the Palatini and Comitatenses, and are to be found in smaller number among the Limitanei. Thus barbarian Atecotti from Caledonia figure as _auxilia palatina_ in the field armies of Illyricum, Italy, and Gaul;[422] cavalry drawn from the Alani appear as a _vexillatio palatina_ in Italy,[423] and Marcomanni as a _vexillatio comitatensis_ among the troops assigned to the _comes Africae_.[424] Among the troops of the second class we find in the garrison of Egypt Vandals, Iuthungi, and Quadi from the Danube, Franks and Chamavi from the Lower Rhine, Tzanni and Abasgi from the Caucasus,[425] and much the same elements appear in the garrison of Phoenicia.[426] In regard to these troops it may be urged that, since they are organized in cohorts and alae after the old model, they seem to have been incorporated at latest towards the end of the third century, and that such corps, since they can hardly have obtained fresh drafts from their original recruiting-grounds, may have undergone the same transformation as the regiments of Spaniards and Gauls which were sent to Egypt and Syria in the first century. In the case in question this argument may possibly hold good,[427] but in other parts of the Empire it was no longer necessary to send recruiting agents beyond the borders to find barbarian troops. In recording the presence of a _praefectus Sarmatarum gentilium_ in almost every considerable town in North Italy,[428] and of similar officers commanding German _laeti_