For a few years after the peace of 1360 the political influence of Edward III. in western Europe seemed to be supreme. France, prostrated by the results of the English raids, by peasant revolts, and municipal and baronial turbulence, did not begin to recover strength till the thriftless king John had died (1364) and had been succeeded by his capable if unchivalrous son Charles V. Yet the state of the English dominions on the continent was not satisfactory; in building up the vast duchy of Aquitaine Edward had made a radical mistake. Instead of contenting himself with creating a homogeneous Gascon state, which might have grown together into a solid unit, he had annexed broad regions which had been for a century and a half united to France, and had been entirely assimilated to her. From the first Poitou, Quercy, Rouergue and the Limousin chafed beneath the English yoke; the noblesse in especial found the comparatively orderly and constitutional governance to which they were subjected most intolerable. They waited for the first opportunity to revolt, and meanwhile murmured against every act of their duke, the prince of Wales, though he did his best to behave as a gracious sovereign.
The younger Edward ended by losing his health and his wealth in an unnecessary war beyond the Pyrenees. He was persuaded by the exiled Peter the Cruel, king of Castile, to restore him to the throne which he had forfeited by his misgovernment. In 1367 he gathered a great army, entered Castile, defeated the usurper Henry of Trastamara at the battle of Najera, and restored his ally. But Peter, when once re-established as king, forgot his obligations and left the prince burdened with the whole expense of the campaign. Edward left Spain with a discontented and unpaid army, and had himself contracted the seeds of a disease which was to leave him an invalid for the rest of his life. To pay his debts he was obliged to resort to heavy taxation in Aquitaine, which gave his discontented subjects in Poitou and the other outlying districts an excuse for the rebellion that they had been for some time meditating. In 1368 his greatest vassals, the counts of Armagnac, Périgord and Comminges, displayed their disloyalty by appealing to the king of France as their suzerain against the legality of Edward's imposts. The French overlordship had been formally abolished by the treaty of 1360, so this appeal amounted to open rebellion. And when Charles V. accepted it, and cited Edward to appear before his parlement to answer the complaints of the counts, he was challenging England to renewed war. He found a preposterous excuse for repudiating the treaty by which he was bound, by declaring that some details had been omitted in its formal ratification.