Hodgkin (_Cornwall and Brittany_, Penryn, 1911) suggests that the soldiers of Maximus settled on the Loire about 388, and that Riotamus was one of their descendants.

He quotes Gildas as saying that the British troops of Maximus went abroad with him and never returned.

That, however, is an entirely different thing from saying that they settled in a definite part of Gaul.

For this latter statement I can find no evidence, and the Celtic revival in our island seems to provide a better setting for the whole incident of Riotamus.
If Professor Bury is right (_Life of Patrick_, p.

354), Riotamus had a predecessor in Dathi, who is said to have gone from Ireland to Gaul about A.D.428 to help the Romans and Aetius.