This first biography of Richard, third Duke of York, examines the political opposition of a great lord to Henry VI's regime. Active in the government of Lancastrian Normandy, he served twice as lieutenant of Ireland where, on his second visit, he did much to consolidate the trend towards Irish autonomy. The major interest of his career, however, lies in the increasing isolation of a once loyal subject. Suspect in the late 1440s, and even more so after the great revolt of 1450, he was driven into opposition during the following decade despite serving for two effective periods - here evaluated for the first time - as Protector of England. In 1455 violence replaced politics at St Albans, and England collapsed into the Wars of the Roses. Five years later, following his unsuccessful claim to the throne - an event for which fresh evidence is presented - he resorted once again to violence, dying in battle and leaving to his son Edward the claim which brought the first Yorkist to the throne.