The Caroline War was the second phase of the Hundred Years' War between France and England, following the Edwardian War. It was so-named after Charles V of France, who resumed the war nine years after the Treaty of Brétigny (signed 1360). The Kingdom of France dominated this phase of the war. The Black Prince, eldest son and heir of Edward III of England, spent a huge sum of money in order to restore Peter the Cruel to the throne of Castile. The Castilian King was unable to repay him, however, so the Black Prince raised taxes in his domains in Aquitaine. The people's complaints were unheeded, so they appealed to the French King Charles V. In May 1369, the Black Prince received summons from the French king demanding his presence in Paris. The prince refused, and Charles responded by declaring war. He immediately set out to reverse the territorial losses imposed at Brétigny and he was largely successful in his lifetime. His successor, Charles VI, made peace with the son of the Black Prince, Richard II, in 1389. This truce was extended many times until the war was resumed in 1415. Background In the Treaty of Brétigny, Edward III renounced his claim to the French throne in exchange for the duchy of Aquitaine in full sovereignty. Between the nine years of formal peace between the two kingdoms, the English and French clashed in Brittany and Castile. In the War of the Breton Succession, the English backed the heir male, the House of Montfort (a cadet of the House of Dreux, itself a cadet of the Capetian dynasty) while the French backed the heir general, the House of Blois. Since Brittany allowed female succession, the French considered the Blois side to be the rightful heir. The war began in 1341, but the English continued backing the Montforts even after the Peace of Brétigny. The English-supported claimant John of Montfort defeated and killed the French claimant, Charles of Blois, at the Battle of Auray in 1364. By that time, however, Edward III no longer had a claim to the throne of France, so John had to accept the suzerainty of the French king in order to hold his duchy in peace. Thus, the English derived no benefit from their victory. In fact, the French received the benefit of improved generalship in the person of the Breton commander Bertrand du Guesclin, who, leaving