Berno" was a powerful Viking chieftain and naval commander. He appears in contemporary sources such as Annales Bertiniani and the Chronicon Fontanellense. He is first mentioned in the summer of 855. The oldest text that details his origins is the Norman history of William of Jumièges (c. 1070). According to William, the Danes had a custom of requiring the younger sons of kings to leave the kingdom, to reinforce the king's authority; thus, after Ragnar Lodbrok became king, he ordered Björn to lea