Magister militum per Orientem

Magister militum (Latin for "Master of the Soldiers", plural magistri militum) was a top-level military command used in the later Roman Empire, dating from the reign of Constantine the Great. Used alone, the term referred to the senior military officer (equivalent to a war theatre commander, the emperor remaining the supreme commander) of the Empire. In Greek sources, the term is translated either as strategos or as stratelates.

The title of magister militum was created in the 4th century, when Emperor Constantine the Great deprived the praetorian prefects of their military functions. Initially two posts were created, one as head of the foot troops, as the magister peditum ("Master of the Infantry"), and one for the more prestigious horse troops, the magister equitum ("Master of the Cavalry"). The latter title had existed since Republican times, as the second-in-command to a Roman dictator.

Under Constantine's successors, the title was also established at a territorial level: magistri peditum and magistri equitum were appointed for every praetorian prefecture (per Gallias, per Italiam, per Illyricum, per Orientem), and, in addition, for Thrace and, sometimes, Africa. On occasion, the offices would be combined under a single person, then styled magister equitum et peditum or magister utriusque militiae ("master of both forces").

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