Late Roman Army Grade/Rank List under Anastasius

[Nathan Ross]

there is not enough tribunes (two) for slab C to be pertaining to a legion, and the title of tribunus numeri cannot be ignored. I am heavily leaning towards an infantry numerus, a cavalry numerus, plus one ala.

From the 4th century onwards a legion was an infantry numerus, and Vegetius describes the two tribunes who commanded it. Three times on Slab B the unit is described as a legion, and/or the troops as legionaries.

The six tribunes of the old legion probably vanished in the later 3rd century with the demise of the old equestrian cursus (last attested under Probus); by the tetrarchic era the centurionate seems to have expanded to fill the gap, with double-cohort legion vexillations being commanded by praepositii of what appears to be centurion grade (i.e. centuriones ordinarii). The tribunes and prefects that commanded the 'new' legions of the 4th century seem to have risen from the ranks via the Protectores or been appointed directly, as Vegetius suggests.

A cavalry numerus (or vexillatio) could have numbered c.300 men, but there is only one unit on this list, under the command of the τριβοῦνος τοῦ ἀριθμοῦ (literally 'tribunus of the arithmos'). Either the cavalry are part of the numerus, or they are not actually cavalry! No reason to assume additional cavalry units are involved.