Edward the Black Prince compelling Peter of Castile to flee from his kingdom, and in setting up his bastard brother, Henry of Trastámara, as king in his stead. Peter, who was in alliance with Edward III, sent messengers to the Black Prince asking his help, and on receiving a gracious answer at Corunna, set out at once, and arrived at Bayonne with his son and his three daughters. The prince met him at Capbreton, and rode with him to Bordeaux. Many of the prince's lords, both English and Gascon, were unwilling that he should espouse Peter's cause, but he declared that it was not
Edward the Black Prince agreed, and after he had dined the prince chose twelve knights, four English, four Gascons, and four Bretons, to judge between himself and the marshal. After he had stated his case, d'Audrehem replied that he had not broken his word, for the army the prince led was not his own; he was merely in the pay of Peter. The knights considered that this view of the prince's position was sound, and gave their verdict for d'Audrehem. On 5 April 1367 the prince and Peter marched to Burgos, where they celebrated Easter. The prince, however, did not take up his quarters