These expeditionary forces were composed in Gaul, its ground and main essence were vexillations detached from Rhine frontier legions. At the same time epigraphic data enabled us to maintain a structure of military corps, which was an enemy of Constantine I in 312 — we mean a personal guard of Maximianus Herculius and his son Maxentius, in 306 this guard deserted to Maxentius and supported his usurpation. Among the units adherent to Maxentius were elite vexillationsequites promoti, comites domini nostri, Moesiaci, Minervii, Moorish cavalry and also a detachment of spearmen(lanci arii). Apart from units enumerated above, Maxentius had a support from a garrison of the city of Rome, that are praetorian guard and units ofequites singulares Augusti (a cavalry imperial guard formed as early as during the Principate times).

So, when Constantine I defeated Maxentius, a victorious Emperor destroyed a usurper's guard in part — firstly, we mean the praetorian cohorts and the units ofequites singulares Augusti, which were immediate instigators of Maxentius' plot. Also we assume that Constantine abolished a corps of spearmen(lanciarii).

However, we think that the vexillations ofMinervii andMoesiaci still existed after 312, Constantine simply moved them from Italy to Rhine frontier and deprived them of their elite status (rank) of palace units, they were modified into regular frontier garrisons.

Another field guard (the so-calledcomitatus ) defeated by Constantine was a guard of Licinius, this one was a very fluent and incoherent military group, Licinius' field guard existed as a single and united composition only during and for the military campaigns. After completion of a military activity thecomitatus of Licinius was dispersed and stopped to exist. The crucial element of Licinius' military forces were frontier units (legions, vexillations, alae and cohorts) of the Danube regions. These units stood not in the ruler's residence, but in different fortresses at the Danube frontier, so, they were scattered along the entire course of the river.

Inscriptions from Balkan and Danube regions enabled us to trace that vexillations under Licinius' command were mostly of two kind, that are detachments of shield bearers(scutarii) and archers(sagittarii), also Licinius commanded over units of mailed cavalry(catafractarii).

As to field army of Constantine I, we turned to epigraphic data in order to make clear an internal structure of this army. For the most part expeditionary forces of Constantine I established in Gaul consisted of two kinds of military units.