In 845 Hárekr of Denmark sailed up the Elbe and destroyed Hamburg, while in the same year the[21] dreaded Ragnarr Loðbrók, most famous of all Vikings, sailed up the Seine as far as Paris. While on its retreat from Paris, after the usual devastation, a strange and deadly disease, possibly some form of dysentery due to scantiness of food resulting from a hard winter, broke out in the Danish army. Various legends arose in connexion with this event, and it finds a curious echo in the story told by Saxo Grammaticus of an expedition made by Ragnarr among the Biarmians (in Northern Russia) when that people by their prayers called down a plague of dysentery upon the Danes in which large numbers perished. In the end the historical plague was stayed when Hárekr commanded the Vikings on their return to Denmark to refrain from flesh and meat for fourteen days. Whether as a result of the plague or from some other cause Hárekr now showed himself ready to come to terms with Lewis, and for the next eighty years there was complete peace along the Eider boundary. The whole of the coast was still open to attack however; Frisia was hardly ever free from invaders; Brittany was obliged to buy off Danish attacks in