He became convinced that his father's lover was the instigator of the uprisings, so he ordered Eleanor to be incarcerated and finally executed in Talavera de la Reina. After that, Henry fled to Portugal. He was pardoned by Pedro and returned to Castile, then revolted in Asturias in 1352. He reconciled with his brother, only to rebel against him again in a long, intermittent war, which ended with Henry's flight to France, where he entered the service of John II of France. Shortly after, Henry and his men spent time in Peter IV of Aragon's army in their war against Castile (1358). During that conflict, he was defeated and held prisoner in Nájera (1360). He was liberated (with the help of Juan Ramírez de Arellano, among others) and exiled himself to France once more. Then Peter IV of Aragon attacked Castile again. Henry agreed to help him on condition that he would lend his support to destroying his brother, Pedro of Castile. This became the Castilian Civil War. The attack combined Henry's Castillian allies, the Aragonese and the French (a company of Bertrand du Guesclin's mercenaries, expelled by Pedro, who had taken refuge in Guyenne). Henry was proclaimed king in Calahorra (1366). In return, he had to reward his allies with titles and riches for the help they had provided. This earned him the nickname "el de las mercedes" ("mercedes" being Spanish for "mercies"). Pedro of Castile fled north to Bordeaux, the capital of the English dominions in France, where Edward, the Black Prince held court. Edward agreed to help Pedro recover his throne. Despite the fact that the army suffered so badly from dysentery that it is said that one out of every five Englishmen would not return home, on 3 April 1367 an Anglo-Gascon army, led by Edward and his younger brother, John of Gaunt, 1st Duke of Lancaster, met the Castilian forces (supported by French mercenaries under Bertrand du Guesclin). Pedro then defeated Henry in the Battle of Nájera, but Henry escaped and returned to France under the protection of Charles V of France. King Pedro and Prince Edward parted ways over the funding of the expedition, and the Black Prince returned to Bordeaux, having contracted an illness on this expedition that would ail him until his death in 1376.