was
magister equitum from 361 to 369 under several Roman emperors, from
Julian to
Valentinian I. Accordingly, he had himself depicted on his richly decorated
marble sarcophagus as a fighting
equestrian general (centre).
Musée Saint-Remi,
Reims. The office of
magister militum was created in the early 4th century, most likely when the Western Roman emperor
Constantine the Great defeated all other contemporary Roman emperors, which gave him control over their respective armies. Because the
Praetorian Guards and their leaders, the
Praetorian Prefects, had supported Constantine's enemy,
Maxentius, he disbanded the Guard and deprived the Prefects of their military functions, reducing them to a purely civil office. To replace them, he created two posts: a commander of the
infantry, the
magister peditum ("master of foot"), and a more prestigious
cavalry commander, the
magister equitum ("master of horse"). These offices had precedents in the immediate imperial past, both in function and idea; the latter title had existed since
republican times, as the second-in-command to a
Roman dictator. Under Constantine's successors, the titles were 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 in a single person, then styled
magister equitum et peditum or
magister utriusque militiae ("master of both forces"). Overall, lower-level
magistri were assigned according to circumstances, with varying numbers employed in a given area. Some were directly in command of the local mobile field army of the
comitatenses, which acted as a
rapid reaction force. Other
magistri remained at the immediate disposal of the emperors, and by the late fourth century or early fifth century were termed
in praesenti ("in the presence" of the emperor). Over the course of the fourth century in the
Western Roman Empire, the system of two imperial
magistri remained largely intact, with usually one
magister having paramount authority (such as Bauto or Merobaudes, the main power behind the appointment of emperor Valentinian II.) This tendency culminated in
Arbogast, who inherited the position of western
magister militum and used it to functionally usurp emperor Valentinian II, either killing him or driving him to suicide before appointing his own puppet emperor, Eugenius. In the west, the position (often under the title of
magister utriusque militiae or MVM) remained very powerful until the formal end of the empire, and was held by
Stilicho,
Aetius,
Ricimer, and others. In the east, emperor Theodosius I (379–395) expanded the system of two
magistri militum to include an additional three
magistri. For a long time these generals were used in an ad hoc manner, being employed wherever they were needed. Eventually in the fifth century their positions became more firmly established, and there were two senior generals, who were each appointed to the office of
magister militum praesentalis. After the final
partition of the Roman Empire in 395, the office continued to exist both in the
Western and
Eastern parts of the divided Empire. One of the most notable examples of prominence and increasing importance of that military office occurred with
Marcellinus, who was
magister militum in
Dalmatia, acting not only as regional military commander, but also as effective governor in the entire region, from 454 to 468.
Continuation and evolution in the Byzantine Empire The office of
magister militum consequently evolved in nature and scope during the early
Byzantine period. During the reign of Emperor
Justinian I (527–565), with increasing military threats and the expansion of the Byzantine Empire, the posts of the eastern generals were overhauled: the
magister militum per Armeniam in the Armenian and Caucasian provinces, formerly part of the jurisdiction of the
magister militum per Orientem, the
magister militum per Africam in the reconquered
African provinces (534), with a subordinate
magister peditum, and the
magister militum Spaniae (c. 562). In the course of the 6th century, internal and external crises in the provinces often necessitated the temporary union of the supreme regional civil authority with the office of the
magister militum. In the establishment of the
exarchates of
Ravenna and
Carthage in 584, this practice found its first permanent expression. In various provinces of the Exarchate of Ravena, from
Venetia to
Naples,
magistri militum were appointed both as local military commanders and provincial governors. For example, such was Mauricius, who was
magister militum of
Byzantine Venetia in 639. After the loss of the eastern provinces to the
Muslim conquest in the 640s, the surviving field armies and their commanders formed the first
themata. ==Later, less formal use of the term==