Cohort commander?

[D B Campbell]

I hesitate to criticize the venerable L&S, but does this actually refer to a centurion in a mixed auxiliary cohors equitata, rather than a cavalry troop?

L&S aren't infallible. I'd agree that this looks like a cohors equitata.

The fact that the centurion is asking for citizenship for his daughter made me initially think that it must be an auxiliary unit, but since soldiers were still forbidden from marrying at this point, his daughter would have been illegitimate, therefore lacking citizenship, unless I'm mistaken, so I guess that proves nothing. The abbreviated praenomen suggests that the centurion was a citizen, although I'm not sure if that nomenclatural convention was still current in Trajan's time. I recall reading somewhere that citizens could enlist in auxiliary units, but I can't think of the source off hand.

As you say, the fact that soldiers were forbidden to marry doesn't mean that they couldn't have illegitimate offspring. On discharge, the non-citizen auxiliary soldier received citizenship for those illegitimate offspring and for himself.

However, what if -- as in this case -- the auxiliary soldier (a centurion, as it happens) already had citizenship? (Accius Aquila's tria nomina shows that he is a citizen; he had perhaps been promoted from a legion to the post of auxiliary centurion.) Under Roman law, the offspring of a Roman citizen and a peregrine woman did not automatically receive citizenship, hence Accius Aquila's request is understandable.