Between Pedro and the English court a firm alliance had existed from the time when the former so nearly married the Princess Joan, and immediately the king heard of the expedition against him he issued orders that no English knights should take part in it. The order, however, came too late. The English knights had already marched into Spain with Du Guesclin. As for the English who formed no inconsiderable portion of the great companies, they had already declined to obey the king, when, at the insistence of the pope and the King of France, he had ordered them to disband.

On Pedro's arrival at Bordeaux with his three daughters and his son, they were kindly received by the Black Prince, courtesy and kindness to those in misfortune being among the leading characteristics of his nature. Pedro, cruel and ruthless as he was, was a man of great eloquence and insinuating manners, and giving his own version of affairs, he completely won over the prince, who felt himself, moreover, bound in some degree to support him, inasmuch as he, an ally of England, had been dethroned by an army composed partly of English. Pedro made the most magnificent promises to the prince in return for his aid, ceding him the whole of the province of Biscay, and agreeing to pay the British troops engaged in his service when he regained his throne, the Black Prince engaging to pay them in the meantime.