=William I, 1known as William the Conqueror. ?1027–1087, duke of Normandy (1035–87) and king of England (1066–87). He claimed to have been promised the English crown by Edward the Confessor, after whose death he disputed the succession of Harold II, invading England in 1066 and defeating Harold at Hastings. The conquest of England resulted in the introduction to England of many Norman customs, esp feudalism. In 1085 he ordered the Domesday Book to be compiled