Jasper, Earl of Pembroke, Duke of Bedford, brother and uncle of kings, was a central figure in the Wars of the Roses, and the Lancastrian claimant during the reign of Edward IV. The second son of Owen Tudor and the widowed queen Katherine of Valois, he was the half-brother of Henry VI, who gave him a prominent role at court. As one of England's major nobles and a potential successor to Henry, he was seen as a threat by Yorkists. He took part in the major battles of the war, leading the Lancastrian forces at Mortimer's Cross and Tewkesbury. The tempestuous politics in England meant that he had to spend time in exile in Brittany, taking his nephew, Henry, with him. Under Jasper's influence, Henry prospered and returned to England to defeat Richard III at the Battle of Bosworth, leading to the establishment of the Tudor dynasty. Despite his important place in history, Jasper has become the forgotten kingmaker, neglected by historians. This book is the first full academic study of him, drawing upon contemporary sources from England, Wales and France, and the wider historiography to present a detailed and superbly-researched biography.