Castilian Civil War
The throne was held by his second cousin Henry of Trastámara (Henry II of Castile), Peter of Castile's illegitimate brother, who had defeated him in the Castilian Civil War in 1366 and assumed the crown. After one or two indecisive campaigns, all parties were ready to accept the mediation of Pope Gregory XI. The conditions of the treaty, ratified in 1371, included a marriage between Ferdinand and Leonora of Castile. But before the union could take place Ferdinand had become passionately attached to Leonor Telles de Meneses, the wife of one of his own courtiers. Having procured a dissolution of her previous marriage, he lost no time in making Leonor his queen.