According to an 850 entry of the Annales Fuldenses, "Hrørek the Norseman () held the vicus Dorestad as a benefice with his brother Haraldr in the time of the Emperor Louis the Pious. After the death of the emperor and his brother he was denounced as a traitor - falsely as it is said - to Lothair I, who had succeeded his father in the kingdom, and was captured and imprisoned. He escaped and became the faithful man of Louis the German. After he had stayed there for some years, living among the Saxons, who were neighbours of the Norsemen, he collected a not insubstantial force of Danes and began a career of piracy, devastating places near the northern coasts of Lothair's kingdom. And he came through the mouth of the river Rhine to Dorestad, seized and held it. Because the emperor Lothar was unable to drive him out without danger to his own men, Hrørek was received back into fealty on the advice of his counsellors and through mediators on condition that he would faithfully handle the taxes and other matters pertaining to the royal fisc, and would resist the piratical attacks of the Danes." The Annales Bertiniani also records the event: "Hrørek (), the nephew of Haraldr, who had recently defected from Lothar, raised whole armies of Norsemen with a vast number of ships and laid waste Frisia and the island of Betuwe and other places in that neighbourhood by sailing up the Rhine and the Waal. Lothar, since he could not crush him, received him into his allegiance and granted him Dorestad and other counties." The Annales Xantenses briefly report: "Hrørek the Norseman (), brother of the mentioned younger Haraldr, who was earlier dishonored by Lothar, fled, demanded Dorestad back, deceitfully inflicted much evil on the Christians."