The Roman Army, 31 BC–AD 337: A Sourcebook

The army in the later empire 233
Constantine (AD 307–337), using elements of Diocletian’s field
force, developed this part of the army, gave it a formal, permanent
structure, and granted its members (comitatenses) special privileges.
However, territorial troops (limitanei) remained permanently
stationed in provinces on the frontiers, and the essential structure
of the Diocletianic system remained intact; large sections of the
frontier zones, which might include territory from several civil
provinces, were under the control of duces who commanded the
territorial troops. Constantine’s abolition of the praetorian guard
in AD 312 was partly dictated by political expediency in that it had
supported his opponent Maxentius. But other groups, the protectores
and the scholae Palatinae, had already increasingly taken over
responsibility for protecting the emperor’s person. Constantine
accepted the solutions to the military problems of the empire which
had been arrived at by experimentation and experience, and with
limited innovation provided the best hope for the maintenance of
Roman power in the long term. Neither Diocletian nor Constantine,
however, fundamentally changed the political set-up in the empire,
in which the emperor still depended on the support and loyalty of
his troops, with whom he built up a personal association, whose
emoluments he guaranteed, and to whom he presented himself as a
successful military leader. The soldiers, recruited from the lower
classes, received privileges and status through military service which
set them above other people from the same class.
There are few reliable literary sources for this period, and in particular
we lack a good narrative historian, since the extant text of Ammianus
Marcellinus only begins in AD 353. The single most important source
is the Notitia Dignitatum, an official document compiled around AD
395, which contains a series of entries for the eastern and western
parts of the empire as it was divided at that time, listing the main office
holders. In the case of the military officers, the units under their
command are set out. From this evidence it is possible to discover the
troops serving in the various arms of the service, and plot the
development and use of certain units from Diocletian’s time. The
complexity and scale of the document, however, make it impossible to
reproduce in a sourcebook of this nature. Legal texts provide useful
information about the privileged status of the army and concessions
granted to individual groups of soldiers. Inscriptions and papyri are
less numerous than in the earlier empire, and so less is known about
the careers of soldiers and their commanders, and the role of the army
in local life. Indeed important aspects of the later army remain obscure,
for example, the number of soldiers, rates of pay and emoluments,