Who Commanded a Cohort in an Imperial Legion?

[Nathan Ross]

There's a theory that each of the five equestrian tribunes commanded two cohorts, although I don't think there's any real evidence for this other than the numbers! More probably, the senior centurion was in overall charge of each individual cohort - the pilus prior, or the primus pilus in the case of the first cohort. If a cohort was split from its parent legion then it became in effect a vexillation, and vexillations were commonly commanded by primipilares, or sometimes tribunes; there's a brief thread about that here.

- Nathan