Late Roman Army during the 5th century

[ValentinianVictrix]

To avoid these inconveniences, the young men enlist in the auxiliaries, where the service is less laborious and they have reason to expect more speedy recompenses.'

Another reason to distrust Vegetius - the 'auxxiliaries' were no longer in existance by the time he wrote (whether that was the later 4th or the later 5th c.). These differences between both services no longer applied in the Late Roman army.

I'm not sure I agree with you on this Robert. Auxilliaries are mentioned a number of times in Ammianus, both in the context of auxilia units and also as foreign mercenaries hired for the occasion i.e. the 'Sythian Auxilliaries' with Julian on his Sasanid campaign, the 'Taifali auxilliaries' who Constantius II approached for assistance against the 'Free Sarmatians' and the 'Limogantes', these are just a couple of examples. I am sure I have read in my collection that those who enrolled in the auxilia units were not expected to perform the non-combat roles that the Legiones were expected to perform i.e. building camps and roads. I believe Heather noted that an infantryman in an auxilia unit received higher pay than those in the Legiones, and there was no obligation for your son to serve in the auxilia when you retired.

I agree that the difference between the roles of the legiones and auxila units on the battlefield may have been almost the same by the Late Roman period, not withstanding Vegetius stating that they were best posted on the wings of the Legiones. Auxilia units also appear to have formed the reserve forces at Argentoratum and Adrianopolis.