It is August 15th, 778, in the height of the Pyrenean summer, the only time when the mountains of Roncesvalles usually reveal all their lush greenery—if one is lucky enough to find them free of mist. During the Emperor’s lifetime, no chronicler dared to record the defeat. Not only did they omit it, but they described the return to France as entirely ordinary. But twenty years after the battle, the new Annales Regii dared to record the Frankish disaster at Roncesvalles:
“At the summit, the Vascones, having laid an ambush, attacked the rearguard and threw the entire army into great turmoil. And although the Franks seemed superior to the Vascones in both arms and spirit, they were, due to the harsh terrain and the unequal nature of the combat, rendered inferior. In this clash, many of the royal courtiers to whom the king had entrusted command of the troops were killed, the baggage train was looted, and the enemy, thanks to their knowledge of the terrain, immediately dispersed in all directions. The grief caused by this wound clouded in the king’s heart much of the joy brought by the successes in Hispania.”
(New Annales Regii, Ed. Pertz-Kurze, pp. 50–51)
The Vascones, having prepared an ambush at the summit, attacked the rearguard, throwing the entire great army into disorder. And although the Franks ed themselves superior to the Vascones both in arms and in courage, due to the roughness of the terrain and the unequal nature of the battle, they were overcome. In this combat, most of the courtiers to whom the king had entrusted command were killed, the baggage was plundered, and the enemy, using their knowledge of the land, dispersed rapidly. The grief from this failure clouded, in large part, the king’s heart regarding the happy events achieved in Hispania.
Twenty years later, around 830, Einhard—who personally knew Emperor Charles—was the first to name, in writing, the commanders of the various army corps killed in the battle with the Vascones. As one might expect, the Frankish chroniclers do not say a single word about the presence or actions of Emperor Charles during the battle. But in an event that shook "the entire great army" and in which nearly all the commanders were killed, it is not possible that Charlemagne was absent. It is reasonable to suppose that, given the way things unfolded—in a setting usually shrouded in fog and forest—he opted to save the vanguard by making a swift retreat toward safer grounds.
The question of who organized the ambush is more obscure. Auzias suggests Duke Lupo II of Vasconia. In the forged Letter of Alaón, fabricated by the well-known forger Pellicer, Lupo is credited with leading the ambush. He would certainly have had motive, considering the recent conquest of Vasconia by Charles and the usual trail of crimes and plunder that accompanies any war. But the letter also claims that Lupo was later captured by Charlemagne and disgracefully hanged. The truth is that nothing more is known of Lupo after 778, though it is known that his son succeeded him in office. The History of Languedoc ed what was said in the Letter of Alaón. This fabrication stood until Benjamin Guérard exposed the document as a forgery.
This defeat, comments Campión, had two important consequences: “for the vanquished, a desire for revenge and to subjugate all of Vasconia by force of arms; for the victors, a motivation to ally with the Saracens—or rather, with the Aragonese Muladíes (the Beni Fortún, of Vasconic origin, probably), who, out of ambition, converted to Islam and later rose as semi-independent petty kings.”
Campión continues: “Thus began a very obscure period of political fluctuation, whose scattered accounts the Vascones sometimes subjected to the Franks, sometimes at war with them, sometimes friends with the Moors, sometimes fighting them: swaying with convenience.”
That is all that is truly known about the Battle of Roncesvalles. Everything else is mere conjecture, falsehood, or embellishment—though sometimes all three are skillfully interwoven, as in the works of Menéndez Pidal. In the cited work, La Chanson de Roland y el neotradicionalismo (p. 199), he fiercely attacks the Carolingian sources—not so much for their flattery of Charles or their offense to the victors, but because they unequivocally and categorically attribute the attack to the Vascones. Menéndez Pidal criticizes the chroniclers for portraying the battle as a mere act of pillaging and imputes to them what they do not explicitly say: “at the hands of bandits, without home or land.”