Baldwin II (died 918) was the second ruler of Flanders, who, from his stronghold at Bruges, maintained, as his father Baldwin I before him, a vigorous defense of his lands against the incursions of the Norsemen. On his mother’s side a descendant of Charlemagne, he strengthened the dynastic importance of his family by marrying Aelfthryth, daughter of Alfred the Great, of Wessex, Eng.