The sources describe a devastating defeat for the Franks, who were driven down into the narrow valley where the Errekabeltz River (the black creek) runs. Chronicles detail the complete destruction of the Frankish forces, stating that "among many others," notable figures such as Agiardo or Einhard (Aggiardus or Eggihardus), the king’s palace seneschal, Anselmus, the court’s palatine, and Roland, the prefect or marquis of the Brittany march, were killed.
The Astronomus Limusinus also noted that the “victory caused many deaths,” but chose not to list the names, claiming they were already well known to all (vulgata sunt). This poetic omission is regrettable from a historical perspective.
In the aftermath, Charlemagne rapidly retreated from the battlefield, abandoning his men and the slain. He managed to return to his palace in Herstal by October of the same year, traveling at an average speed of 27 kilometers per day, a stark contrast to the daily average of 8 kilometers from April 14 to August 15. This hasty retreat was possible only with a small detachment, likely at a gallop, particularly given that Charlemagne made at least two stops en route to Herstal.
King Charles never returned to the battlefield either to aid his own soldiers or to recover the bodies. Logically, the psychological impact of the battle was terrible; the chronicles refer that such a great misdeed cast gloomy shadows over the mind of the king. Charles barely left Herstal from September 778 to May of the following year, pondering why he had lost divine favor. This, in turn, explains why the official chronicles remained silent about the event during the emperor's lifetime. He never returned to the Basque Country.
