St.Athanasius 500 soldiers reference?

[Julian de Vries]

So 5000 men. Many thanks for clearing that up. Now, about the dux, here is an inscription of a dux commanding two legions:

Circa AD 300 Thrace IGR I.1496; translation of Stein, <Traianus 1> PW 6A (1937), col. 2088:

Traianus Mucianus duc(enarius) miles cohortis I Concordiensium et legionis II Parthicae, eques cohortis VII praetoriae, evocatus, (centurio) protector leg(ionis) XIII gem(inae), (centurio) prot(ector) vigilum, (centurio) pr(o)tect(or) urb(anicianus), prot(ector) cohort(is) V pr(ae)t(oriae), princeps prot(ector), primop(ilus), … praefectus leg(ionis) III Flaviae, dux legionum VII Claudiae et IIII Flaviae…