John of Gaunt of Castile. As his father and elder brother, Edward, the Black Prince, became incapacitated due to poor health, Gaunt assumed control of many government functions, and rose to become one of the most powerful political figures in England. He was faced with military difficulties abroad and political divisions at home, and disagreements as to how to deal with these crises led to tensions between Gaunt, the English Parliament, and the ruling class, making him an extremely unpopular figure for a time. John exercised great influence over the English throne during the minority of King Richard II, and the ensuing periods
John of Gaunt was simply abandoned and the army returned ingloriously to England. John of Gaunt received most of the blame for the debâcle. Partly as a result of these failures, and those of other English commanders at this period, John was one of the first important figures in England to conclude that the war with France was unwinnable because of France's greater resources of wealth and manpower. He began to advocate peace negotiations; indeed, as early as 1373, during his great raid through France, he made contact with , brother and political adviser of Pope Gregory XI, to let the pope know