In his book Historical Investigations of the Antiquities of the Kingdom of Navarre, Joseph Moret, chronicler of the kingdom, opposes his version of the battle to that of Juan de Mariana, which he considers lacking in rigor and even orthodoxy and honesty. In general, Moret criticizes those authors who, like Mariana, use the Historia Karoli Magni et Rotholandi, also known as the Turpin Chronicle, as a historical source for the study of the battle of Errozabal or any other historical event. According to Moret, far from being an actual chronicle, the Historia Karoli Magni et Rotholandi is a beautiful piece of literature that should not be used as a historical source. Moret emphasizes the illicit character of Mariana's chronicle by specifying that, although in the Latin edition of his work the author makes explicit mention of Einhard's Vita Karoli Magni Imperatoris, in the Spanish edition he states that the encounter between the Basques and the Franks did not take place because there was no chronicle to register such an encounter, deliberately removing Einhard's Vita from the bibliography in that edition. It is certainly difficult to know what Mariana's motivations might have been, but Moret’s complaint was legitimate.

Moret also observes that the battle of Errozabal is so recurrent among foreign authors that ‘after almost nine hundred years it seems that it happened yesterday’. However, the author adds, this historical event had not been studied in detail by native authors to that day, and most of those who had written about the battle had for the most part merely ‘repeated the story that they have found disturbed and confused in other author's works’. Moret even considers that this is the effect of a ‘very strong and foreign voice’, implying that there were still in the seventeenth century political or cultural motivations for altering the historical events.

More than three centuries later, we have not still advanced much.