Военная организация поздней римской империи в 253—353 гг. От реформ императора Галлиена до периода тетрархии (253—305) - Евгений Александрович Мехамадиев

a maximal scope of historical sources for the time of 253–353, we may deduce that during this period Roman Empire had only two selfsufficient field (mobile) armies. The first one, which is earlier, is that established by the Emperor Gallienus around the late 250th (between 256/257 and 260), the second one, which is more late, is that of army of comitatenses established by Constantine I the Great in 312–324 but mentioned officially for the first time only in 325. All the rest troops took part in campaigns of the Tetrarchs, i. e. existed during 284–312, were only the field personal guards of the Tetrarchs, but not the self-sufficient armies as such.

These guards were private elite military retinues of each of the Tetrarchs, they consisted of different military detachments. These guards were not the armies, their effective was too small for to call them as armies. Field guards of the Tetrarchy were the groups of military units collected for the specific period of time, i. e. in order to take part in certain military expeditions.

As to self-sufficient expeditionary armies, we may say that they were permanent regional troops, i. e. they located in strictly defined regions of Empire. Army of Gallienus was a dispersed military corps, i. e. this army, in turn, consisted of some military groups, and each group occupied the relevant region. Sources on Gallienus' reign (not only narrative, but also epigraphic and numismatic) gave us a chance to trace three such military groups. One of them located in Northern Italy, its head-quarter was Milan, another stood in the province of Raetia north of the Alps, a third one resided at the Danubian frontier.

An Italian military corps was established for the first time as early as 256/257, it consisted of units called vexillations, that are military units detached from the staff of old frontier legions, we mean Rhine, Alpic, Britains and Danubian legions. All this legions have existed since early Principate times. A coin issue of Gallienus dated by 257/258 or 260/261 mentions 18 legions, which detached their vexillation to Gallienus' field corps. An original effective of this corps was nearly 10 000 men, later it was reinforced up to 15 000 men, mainly thanks to units of Dalmatian cavalry and old frontier alae and cohortes, which had served earlier at the Danubian frontier. We may consider as an additional and composite element of this corps the rapid Moorish cavalry.

Besides units, which defended North Italy (Milan military corps), we may recognize one another group of vexillations, this one served in Raetia north of the Alps — these were the vexillations of Rhine frontier legions, they were called Germaniciani. But besides Italian and Alpic expeditionary corps, an army of Gallienus included a third group located at the Danubian frontier. The third group served in upper Pannonia, it defended Danubian frontier from invasions of external barbaric tribes and from internal enemies, such as different usurpers. Inscriptions from the Roman fort of Petovio in Pannonia are our only evidence which cast a light upon an existence of this third military corps, these inscriptions mention vexillations of two old Danubian frontier legions, that are of V Macedonica and XIII Gemina.

As for vexillations themselves, we have to say that they consisted of both cavalry and infantry. Each of the vexillation comprised of five legionary cohorts, more precisely, each legion could detach up to five its cohorts in order to build a vexillation.

In 273 a hard and decisive battle at the Syrian city of Emesa gave a victory to a new Roman Emperor Aurelianus, who destroyed the forces of rebellious Palmyric kingdom. Aurelianus sent at the Near East expeditionary corps, which comprised of all Gallienic vexillations of the North Italy and Alpic front, with except for Rhine forces commanded by Gallic usurpers. An internal structure of Aurelianus' army consisted of Dalmatian cavalry, vexillations from Alpic legions (we mean II and III Italica), Danubian legions (XIII Gemina, V Macedonica, II Aduitrix, VII Claudia, IV Flavia), detachments of Moorish cavalry and also units of a mailed cavalry.

All these units striked a powerful blow at the Palmyric kingdom and reestablished a Roman control over the Near East provinces. But, at the same time, this expeditionary army finally was dismissed and dispersed over different places of Roman frontier, especially at the Danubian and Italian fronts.

Military units took part in battles against the Palmyric kingdom returned in their home (native) provinces, mainly at the Danubian front, but they served there as self-sufficient and single garrisons, without any strict addiction to their «maternai» legions.

Our sources don't let us to say about the strict and defined strength of military detachments, moreover, we can not say about the general and constant numbers for all the kinds of troops. As for effective of four regional armies of the Tetrarchy themselves, we deduced that an effective was 80 000 men per each. When Diocletian devided Empire in four large territorial parts in 293 and, therefore, established a system of the Tetrarchs (i.e. a power of the four со-rulers, two of them were the senior Augusti, and two rest persons were the junior Caesars), each of the part had its own army. All four armies were strictly the frontiers, each consisted of 80 000 men. So, a general strength of all the Roman land army during the reign of Diocletian was nearly 320 000 men.

The main military struggle, the crucial event of 293–305 was a Persian campaign of Caesar Galerius, which happened in two stages. The first stage happened in Autumn of 296, it was unsuccessfull for the Romans and ended in defeat of Galerius' army. The second stage, most important and desicive, lasted from Spring to Autumn of 298, at this time the Romans defeated Persian king Narseus within a territory of the Northern Mesopotamia, in upper Tigris and Euphrates.

A defeat of the Persians led Diocletian to the vast reorganization of the Roman defence system at the Near East and the South Caucasus. Thanks to victory over the Persians in