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 Armagnac, did not forget the offence, and Froissart speaks of it as the "first cause of hatred between him and the prince". A more powerful cause of this lord's discontent was the non-payment of an annual pension which had been granted him by Edward. About this time he agreed to marry Margaret of Bourbon, sister of the queen of France. The Black Prince was annoyed at this betrothal, and, his temper probably being soured by sickness and disappointment, behaved with rudeness to both D'Albret and his intended bride. On the other hand, Charles offered the lord the pension which he