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

34 The Roman Army
units were now being stationed more permanently in established bases
in the frontier provinces. In the early imperial period auxiliaries were
probably conscripted through a levy imposed on conquered peoples,
and some conscription will always have been needed, though in the later
period, with improved service conditions, the number of volunteers is
likely to have made up a larger proportion.
By the end of Augustus’ reign auxiliaries may have been as numerous
as legionaries, being organized in cavalry alae containing about 500
men (subdivided into turmae), part-mounted cohorts containing about
120 cavalry and 480 infantry, and infantry cohorts containing about
480 men (subdivided into centuries). A development perhaps dating
from the reign of Vespasian saw the creation of some larger (milliary)
units containing between 800 and 1,000 men. Many of the special
posts available in the legions were also available in the cohorts and
alae of the auxilia. Eventually the distinction between legions and auxilia
became blurred and citizens are found serving in the auxilia in greater
numbers (Cheesman 1914; Kraft 1951; Holder 1980; Saddington 1975;
1982; Eck and Wolff 1986; Dixon and Southern 1992; text no. 182).
Units of infantry and cavalry (pedites singulares and equites singulares)
served as special guards in attendance upon officers and
magistrates such as legionary legates, procurators, and most
importantly, proconsuls and imperial legates. In the Republic
commanders had traditionally taken some of their military guards from
Italian allies or foreign troops. In the imperial period, although unit
commanders recruited their guards from the soldiers under their direct
command, soldiers who formed the guard of the provincial governor
were chosen on temporary assignment from the auxilia stationed in
the province. In the major consular provinces, units of pedites singulares
and equites singulares were probably equal in strength to individual
regular auxiliary alae and cohorts, and were commanded by men with
the rank of legionary centurion. These units served to confer honour
and prestige on men in authority; they acted as a bodyguard, assisted
in ceremonial occasions, and performed police duties; in battle they
attended upon the person of the commander, although there is no
evidence that they formed a kind of strategic reserve.
44 ILS 2500, inscription, near Moguntiacum (Mainz), Upper
Germany, early 1st C.AD
Adbogius, son of Coinagus, of the Petrocorian people (in Gaul),
cavalryman of the ala of Ruso, 28 years old, ten years’ service, lies
here. His freedman set this up in accordance with his will.