In 844, Vikings invaded Bordeaux and killed Duke Seguin II. His heir William was killed trying to retake Bordeaux in 848, though some sources say he was only captured and later deposed by the king. By the year 853, Sans Sancion, the Basque leader, was recognised as duke by Charles the Bald. During that same year, Muza of Tudela, relative of the Basque princes, invaded Vasconia and made Sans prisoner. In 855, Sans died and was succeeded by Arnold, who died fighting against the Norse in 864.