Peter, the Prince of Wales and England. Background After the Treaty of Brétigny favorable to England was signed in 1360, ending the Hundred Years' War, France tried to avoid open conflict with England and tried to associate with Castile to gain an advantage. France had to find employment for the mercenaries of the great companies dedicated to pillage now that there was no war. In late 1365, Charles V of France, with the help of Pope Urban V, succeeded in diverting temporarily most of the great companies. Under the pretext of carrying on a crusade against the Moorish Kingdom of Granada, the Pope paid for an expedition to Spain. Later on, France and Aragon paid to recruit these troops for Henry's cause, removing the free companies from France and supporting the ascent to power in Castile of their favorite. The strength of the army of Henry rested primarily on these companies, groups of mercenaries that had participated in the Hundred Years' War, composed mainly by Bretons, Gascons, English and French. The Black Prince (Edward, Prince of Wales and Duke of Aquitaine) was the main beneficiary of the peace treaty of 1362 between England and Castile that allowed Castile to keep safe maritime trade routes and in turn England kept herself safe from the large Castilian war fleet. Edward did not seem interested in prohibiting the participation of his Gascon and English subjects in the Castilian Civil War on the side of the pretender Henry, although it favoured France and was against the interests of England. Aquitaine was going through a difficult stage as the main funding sources for this traditionally poor region were the wine industry, which was depressed and warfare. Aquitaine no longer received subsidies from England and needed other sources of revenue. England would not allow France to ally with Castile to establish Henry as the new king. When Peter I of Castile, who was losing the war against his stepbrother Henry and his mercenary troops, sought help, King Edward III of England ordered Sir John Chandos the constable of Aquitaine and other commissioners to ensure that the Gascon and English mercenaries stopped assisting Henry. In February 1366, England sent several Gascon great companies to strengthen the position of King Peter but these measures proved insufficient and Peter had to flee Castile. Army composition England then decided to recruit a huge army of mercenaries to support the cause