We assume that military detachments which located in Bithynia in the spring of 337 as equally as all the rest part of the Danube expeditionary army which continued to be in Thrace, came under the power of Constantius II, a middle son of Constantine I, this event happened already in the summer of the same year. Up to the summer of 337 Danube frontier didn't subordinate to Constantius because in 335 Constantine I gave Balkan-Danube regions under the government of his nephew, Dalmatius the Junior, and it's natural that Thrace also was among the territories which came under Dalmatius' jurisdiction. We need to point out that Thrace was a residence-place for the army ofcomitatenses, so, between 335 and 337 the Danube army ofcomitatenses was headed strictly by Dalmatius the Junior.

Respectively, at the beginning of June of 337 (we follow the dating of R. Burgess) Constantinople became a place for bloody palace plot, which was supplied by murders and violation, a supposed instigator and promoter of this plot was Constantius II, and its victims were Hannibalian, another nephew of Constantin I and a brother of Dalmatius the Junior, and Dalmatius himself. This political crisis resulted to extension of territorial power of Constantius II, because he gained a power over lands which earlier obeyed Dalmatius the Junior, precisely, these were provinces along the Lower Danube, Thrace, Minor Scythia and the Lower Moesia. So, Constantius II maintained his control over Danube expeditionary forces, which located primarily in Thrace.

As a result, to the summer of 337 Constantius ΙΓ troops included two military groups, the first one located at the Near East frontier and was a frontier army (alae, cohorts and vexillations), the second one resided in Thrace and was an expeditionary army ofcomitatenses. However, we have to point out that it was Constantius II who first relocated essential part of Danube expeditionary forces from Thrace to the Near East. We supposed that between 337 and 342 Constantius II moved many units of Danube army in Syria, Mesopotamia and Arabia.

Inscriptions from Syria, Arabia and Mesopotamia attest a presence of some vexillations within these provinces, and previously, before their relocation to Near East front, these vexillations strictly posted at the Danube front and were integral parts of the army ofcomitatenses, we mean primarily the unitsof Aureliaci, Mauri Illyriciani Constantes, a regiment of Dalmatian cavalry and a band of recruits levied from Thrace.