Over the last few years I have become interested in the reliability of Ammianus and the authenticity of the ‘Germanic threat’ on the Rhine frontier.2 I have recently pursued both issues in a paper examining Julian’s first contacts with the Franks in 355-6, and Valentinian I’s early treatment of the Alamanni a decade later.3 Here I wish to continue the same lines of thinking, concentrating on Valentinian I’s later dealings with the Alamanni.