John Troglita is first mentioned as having participated in the Vandalic War (533-534) under Belisarius, and may be identifiable with another John, who commanded a unit of foederati in the battles of Ad Decimum and Tricamarum [REF].
At some point after 538, Troglita was sent to the Eastern frontier, where by 541 he was appointed dux Mesopotamiae, one of the most important military commands of the region.