ORGANIZATION OF ROMAN IMPERIAL ARMY

The Legion:

LEGIO

5,000+ infantry (pedites)

120 cavalry

         
         
120 horse Supply HQS. 1 COHORS COHORS 2-10
(RECON.) 1 Legatus legionis MILIARIA 480 men each
6 tribuni militum 960 men
1 praefectus castorum
plus adm. staff,
the eagle (aquila),
and medics
         
MANIPULUS

320 men with signum

MANIPULUS

160 men each with signum

         
CENTURIA

160 men and centurion

CENTURIA

80 men each and centurion

Auxiliary Units: The two most common units were ala ("wing") of cavalry and cohors (or cohort) of infantry. While officers (called praefecti, "prefects") were Roman citizens, equipment, drill, and organization varied. Special units included cohors equitata (part mounted unit with infantry formation), irregular numeri (barbarians), archers from Syria and Crete, camel units (from Palmyra), heavy cavalry from Germany.

CAVALRY INFANTRY
ALA (512 men) COHORS (480 men)
16 TURMAE 6 CENTURIAE
(32 men each) (80 men each)

Source: G. Webster, The Roman Imperial Army (London, 1969).