Page "Alemanni" Paragraph 34
On January 2 366 the Alemanni yet again crossed the frozen Rhine in large numbers, to invade the Gallic provinces, this time being defeated by Valentinian ( see Battle of Solicinium ).
In the great mixed invasion of 406, the Alemanni appear to have crossed the Rhine river a final time, conquering and then settling what is today Alsace and a large part of the Swiss Plateau.
At Alba Augusta ( Alba-la-Romaine ) the devastation was so complete, that the Christian bishop retired to Viviers, but in Gregory's account at Mende in Lozère, also deep in the heart of Gaul, bishop Privatus was forced to sacrifice to idols in the very cave where he was later venerated.
It is thought this detail may be a generic literary ploy to epitomize the horrors of barbarian violence.