Einhard, Vita Karoli Magni (Life of Charlemagne)

In recounting the life of Charlemagne, Einhard has occasion to touch on Scandinavian geography (§12) and on specific encounters of the Franks with Danes (§14, §32), including some details about their leader Godofrid / Godfred. For example, in §14 (tr. Turner): "The last of these wars was the one declared against the Northmen called Danes. They began their career as pirates, but afterward took to laying waste the coasts of Gaul and Germany with their large fleet. Their King Godfred was so puffed with vain aspirations that he counted on gaining empire overall Germany, and looked upon Saxony and Frisia as his provinces. He had already subdued his neighbors the Abodriti ... He was murdered [810] by one of his own bodyguard, and so ended at once his life and the war that he had begun."