In 845 Hárekr of Denmark sailed up the Elbe and destroyed Hamburg, while in the same year the 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 847, while Noirmoutier continued to form a basis of attack against Southern France in the Gironde district. The Viking invasions in France had attained much the same stage as that to which we have already traced them in England and Ireland. CHAPTER III THE VIKINGS IN ENGLAND TO THE DEATH OF HARTHACNUT The great development of Viking activity which took place after 855 was certainly not unconnected with the course of events in Denmark itself. Hárekr was attacked by his two nephews in 850 and compelled to share the kingdom with them. In 854 large bands of Vikings returned to their fatherland after twenty years' ravaging in Frankish territory. Trouble now arose between Hárekr and his nephew Godurm (O.N. Guðormr), one of the returned leaders. Civil war broke out and ultimately, after a great fight, the kingship fell to a younger Hárekr, a relative of the late king. A severe dynastic struggle of this kind must have been accompanied by much unsettlement and perhaps by an actual proscription. It would certainly seem that there was some definite connexion between these events and the coincident appearance of the sons of Ragnarr Loðbrók as leaders of a more extended Viking movement both in England and in France. Three of his sons--Halfdanr, Ubbi and Ívarr--took part in the first wintering in Sheppey in 855, while in the same year another son Björn Ironside appeared on the Seine.