chapter 25.

https://www.gutenberg.org/ebooks/25717_

ALEMANNI: A. D. 378. Defeat by Gratian.

On learning that the young Emperor Gratian was preparing to lead the military force of Gaul and the West to the help of his uncle and colleague, Valens, against the Goths, the Alemanni swarmed across the Rhine into Gaul. Gratian instantly recalled the legions that were marching to Pannonia and encountered the German invaders in a great battle fought near Argentaria (modern Colmar) in the month of May, A. D. 378. The Alemanni were routed with such slaughter that no more than 5,000 out of 40,000 to 70,000, are said to have escaped. Gratian afterwards crossed the Rhine and humbled his troublesome neighbors in their own country.

_E. Gibbon, Decline and Fall of the Roman Empire,