In April 1066, Haley's Comet caused panic across Europe. Many feared the world was ending. Within six months, two powerful monarchs in Western Europe were slain, leading to William the Conqueror's rise in England and the end of the Anglo-Saxon way of life. William's rule in England involved building castles, suppressing rebellions, and implementing the Domesday Book in 1085 for a thorough land survey. William's remorseful reflections on his actions in England as expressed in later accounts.