The Frankish historical sources present serious problems of interpretation. The chronicles did not record the events of the campaign against Vasconia in 778 during Charlemagne's life, and the chroniclers who wrote immediately after the emperor's death recorded the episode from a subjective standpoint. For instance, Eginhard states in the Vita Karoli Magni that ‘Charlemagne crossed the Pyrenees, obtained the capitulation of all places and castles that stood in his way, and returned with his army safe and unharmed’, which is far from accurate. The author sought to avoid any mention of the failure of the campaign of 778, omitted any reference to the battle, obviated the events that took place at the gates of Zaragoza and avoided any reference to the events around Pamplona, which ultimately led to the order of destruction of the city and the final withdrawal of the Carolingian troops from Vasconia.

Virtually all the major sources converted failure into victory. In this sense, the Frankish sources strove to emphasize the actual submission of the Basques, which contradicts the events that took place in Errozabal. The Annales Mettenses Priores, the Annales Laurissenses, the Einhardi Fuldensis Annales, and the Reginionis Chronicon record that, once the Hispanics, the Basques, and the Navarrese capitulated, the king returned victorious to his country. The Annales Regni Francorum also records that Charlemagne returned to his country after having subdued the Basques,6 and the Annales Tiliani and the Annales Regni Francorum also record that after having confronted the Basques, Charlemagne returned to France.