Primipilus iterum

[Dagalaifus]

I apologize in advance if this topic has already been covered in RAT. I am confused by the title primipilus iterum, Are you promoted to primipilus iterum after serving as a praefectus castorum, or after serving as a primipilus and then spending time in the tribunates in Rome?
Does the primipilus iterum rank higher in status to the praefectus castorum if the primipilus iterum is serving in a legion? Would a legion have both a primipilus iterum and a primipilus at the same time? What are the duties of a primipilus iterum and do they differ from the primipilus and praefectus castorum? Finally, is a primipilus iterum synonymous with a p.p. bis?

Thank you in advance for answering my questions.

[Renatus]

You may find the late Brian Dobson's PhD thesis 'The primipilares of the Roman army' useful. It is available here:
http://etheses.dur.ac.uk/8434/

[Michael J. Taylor]

A primus pilus bis holds the position two years in a row; the primus pilus iterum holds the position again, but with another position intervening.

To be praefectus castrorum was an equestrian posting that usually followed service as a primus pilus, and often capped a military career. That being said, during the Julio Claudian dynasty, men who were primipilares were drawn into various equestrian positions, some of which were military (serving as a legionary tribunes, an auxiliary cohort commander, or the tribune in one of the Praetorian cohorts, or one of the paramilitary cohorts, but others strictly administrative. As the primus pilus became an important jumping off point for an equestrian careers, we start to see equestrians seeking to be promoted directly to the post, so that the ranks of primipilares were a mix of men who had worked their way up the ranks and those who received the position through political patronage.