The Ogier character is generally believed to be based on Autcharius Francus (or Otkerus), a Frankish knight who had served Carloman and escorted his widow and young children to Desiderius, King of Lombardy, but eventually surrendered to Charlemagne. The Ogier character could also have been partly constructed from the historical Adalgis (or Algisus), son of Desiderius, who played a similar role. The "chanson de geste" does parallel this, and Ogier does seek refuge with the Lombardian king Didier or Désier (as Desiderius is styled in French).