Promotion in a Vexilatio

[Nathan Ross]

I can understand perhaps legions stationed near to Rome, travelling to a central ceremony, but from Britannia (for example) that would seem very restrictive.

Yes, I think we'd need some quite compelling evidence to support this 'ceremony' idea... :-|

Many legions and Auxillia were raised far from Rome, for example IX Hispana... the lead time to create a legion could be a big problem, even for Caesar and the legions he raised in transalpine Gaul before his conquest of Gaul... if I also remember correctly he started raising those legions before he had senate approval?

IX Hispana were probably named after service in Spain, rather than being originally raised there. You're talking about the legions of the late republic now, of course, which in many ways were quite different to the imperial model. Most of Caesar's new legions of the Gallic wars were raised in cisalpine Gaul (i.e. northern Italy), and some were perhaps of dubious citizen status - only the cispadene territories (south of the Po) had full citizenship at that point; north of the river only had the 'latin right', although there were several citizen colonies up there too.

But you 're probably referring to the Alaudae legion, which Caesar raised himself from among the noble youths of southern Gaul. They were later given the numeral V, and were an unusual expedient. But by the period of the Gallic and civil wars, many legions had become more or less the private military forces of their commanders anyway, paid for largely by the commander himself - or promised pay in arrears as the spoils of victory.

These legions would be raised and (supposedly) discharged en masse, perhaps using a cadre of centurions and promoted veterans from the other legions in the field. Vegetius (Epitome II,5) probably preserves some details of republican practice gained from the writings of the Elder Cato; he gives four months as the minimum time needed to train a legion up from scratch. By the empire, things had changed, with legions as standing formations.