The conventional view of Richard III's defeat at the Battle of Bosworth Field in 1485 is that it was due to a loss of support for him after his usurpation of the throne. However, David Hipshon argues that the result might very well have been in his favour, had not his support for James Harrington in a long-running family feud with Thomas, Lord Stanley led to the latter betraying him. Bosworth was the last English battle in which the monarch relied on feudal retainers: at Stoke two years later professional mercenaries were the key to Henry VII's victory. The author examines how the power politics of the conflict between the Stanleys and the Harringtons, and Richard's motives in supprting the latter, led to the king's death on the battlefield, the succession of the Tudors to the throne of England, the 'death of chivalry' and the end of the Middle Ages.