The End of the Primus Pilus

[Nathan Ross]

Reference begins in the 320s and becomes universal soon after.

Thanks Robert. Again, rather later than the apparent disappearance of the Primus Pilus, so the two might not be explicitly connected...

Tom Wrobel (popularis) has pointed me back in the direction of Brian Dobson. Dobson's essay The Primipilares in Army and Society (Kaisar, Heer and Gesellschaft, 2000) has the following, in relation to 'the gradual change from praefectus castrorum legionis to praefectus legionis:

It was important that Severus chose to find commanders for his three Parthian legions from the ranks of the primipilares, on the model of the legion(s) in Egypt. Although all the legions seem to have received prefect-commanders, who were still primipilares, under Gallienus, some time before the end of the century, the link between primipili/primipilares and military service was broken, as the primipilaris became the administrator of the tax known as the primipilum. This development had its roots earier, but consideration of this must be left to another occasion.

The note to this last point directs 'for some discussion' to J.M. Carrie in ZPE 35, 1979 - although I have no idea who this author is or what ZPE might be!

However, the simultaneous disappearance of the primus pilus and the metamorphosis of the praefectus castrorum into the praefectus legionis (equestrian commander of the legion) around the time of Gallienus might perhaps support my third suggestion above: at a time when senatorial legates were being withdrawn, and legions were increasingly operating in smaller and more mobile vexillations, might the protectores have acted as a mechanism for cherrypicking capable and loyal centurions and boosting them into command positions without their having to serve through all the ranks of the centurionate and arrive at primus pilus at a relatively advanced age? There are, I believe, a couple of inscriptions describing precisely this movement.

The old primus pilus position, then, effectively took over the former supply and logistics role of the praefectus castrorum, before being moved entirely out of the military sphere and into civilian life. The prestige of the position, and equestrian membership, was maintained, with the added bonus of hereditary tenure - initially, maybe, a sop to the pride of the old veteran centurions!