Late Roman Army during the 5th century

[Robert Vermaat]

there are a number of cohorts and alae mentioned in the ND as part of the Egyptian garrison that appear to have a barbarian origin - Vandals, Iuthungi, Franks etc.

I guess Egypt was a good place to send them--too far from home to expect to return if they mutinied and started plundering.

Yes and no. When belisarius defeats the Vandals he sends the remainder to Persia, and we never hear from them again. But during the 2nd century (I think it was?), a group of 'displaced' German vanquished troops stole ships and sailed them through the Med all the way back to Germany!