With characteristic caution he dexterously held himself in the background while he made use of the Pope, who had been threatened by the Free Companies in his palace at Avignon and was as anxious to get rid of them as himself.
Pedro's cruelty, misgovernment, and alliance with the Moslem of Cordova served as grounds for a crusade which was proclaimed by Pope Urban; and Du Guesclin, who was placed at the head of the expedition, found in the Papal treasury and in the hope of booty from an unravaged land means of gathering the marauders round his standard.

As soon as these Crusaders crossed the Ebro Pedro was deserted by his subjects, and in 1366 Henry of Trastamara saw himself crowned without a struggle at Burgos as king of Castille.

Pedro with his two daughters fled for shelter to Bordeaux and claimed the aid promised in the treaty.

The lords of Aquitaine shrank from fighting for such a cause, but in spite of their protests and the reluctance of the English council to embark in so distant a struggle Edward held that he had no choice save to replace his ally, for to leave Henry seated on the throne was to leave Aquitaine to be crushed between France and Castille.
[Sidenote: Charles the Fifth] The after course of the war proved that in his anticipations of the fatal result of a combination of the two powers Edward was right, but his policy jarred not only against the universal craving for rest, but against the moral sense of the world.

The Black Prince however proceeded to carry out his father's design in the teeth of the general opposition.