Book excerpt: When William the Conqueror died in 1087 he left the throne of England to William Rufus ... his second son. The result was an immediate war as Rufus's elder brother Robert fought to gain the crown he saw as rightfully his; this conflict marked the start of 400 years of bloody disputes as the English monarchy's line of hereditary succession was bent, twisted and finally broken when the last Plantagenet king, Richard III, fell at Bosworth in 1485. The Anglo-Norman and Plantagenet dynasties were renowned for their internecine strife, and in Lost Heirs we will unearth the hidden stories of fratricidal brothers, usurping cousins and murderous uncles; the many kings - and the occasional queen - who should have been but never were. History is written by the winners, but every game of thrones has its losers too, and their fascinating stories bring richness and depth to what is a colourful period of history. King John would not have gained the crown had he not murdered his young nephew, who was in line to become England's first King Arthur; Henry V would never have been at Agincourt had his father not seized the throne by usurping and killing his cousin; and as the rival houses of York and Lancaster fought bloodily over the crown during the Wars of the Roses, life suddenly became very dangerous indeed for a young boy named Edmund.