Historical sources used in the preparation of this book

The main Carolingian chronicles written immediately after the battle of Errozabal are the following:

• – Annales Mettenses or Annals of Metz, written by an anonymous author in the monastery of Chelles. It is actually two sets of records, one called the Annales Mettenses Priores and the second known as the Annales Mettenses Posteriores. The Annales Mettenses Priores cover a period from 678 (Anno ab incarnatione domini nostri Iesu Christi DCLXXXVIII) to the date of writing, in 805 (Anno dominicae incarnationis DCCCV). Subsequently the Annales Mettenses Priores include an annex extending from 805 to 830 that for the period 805-829 coincides with the Annales Regni Francorum (Anni 806-829 prorsus curn Annalibus regni Francorun concordant). Written 28 years after the Battle of Errozabal, it is chronologically one of the closest sources to the events, so it is of great interest from a historiographical point of view, although direct reference to the battle is extremely sparse and the defeat of the 778 campaign is described in terms of a military victory.

• The Annales Mettenses Posteriores (776-805) represent a timeline or summary of the above, the chronicler having copied passages verbatim from the previous source. In this case, as above, the events of the Battle of Errozabal are discussed only very briefly, with no indication of the defeat. Like most Frankish sources the Annales Mettenses lack subjectivity. This lack of accuracy may be explained if we consider that the Carolingian dynasty descended through the paternal line from St. Arnulf, Bishop of Metz, who died in 641. The bishop's son married Begga, daughter of Pepin the Elder, who gave birth to Pepin the Young or Pepin of Herstal, father of Charles Martel and therefore Charlemagne's paternal great-grandfather. Charlemagne's family was closely linked to the monastery to the point that Gisela, sister of Charlemagne – who Alcuin referred to as a femina verbipotens -, was Abbess of Chelles, which has raised speculation that she personally participated in the writing of the chronicle.

• In any case, as is the case with other sources of this nature, the Annales Mettenses are to a high degree subjective.