After the assassination of King Peter I in 1369, there began a series of disputes and long rivalries between John, Duke of Lancaster (who claimed the Castilian throne as the husband of Constance, eldest surviving daughter of King PeterI and his mistress María de Padilla but recognized as legitimate and in line of succession by the Cortes of 1362), and the two successive Trastámara claimants, HenryII and his son JohnI. After two decades of conflicts of varying intensity, the parties arrived at a compromise through means of the marriage between Prince Henry (son and heir of King JohnI) and Catherine of Lancaster (only surviving child of John and Constance).