Duke of Normandy and one of the greatest English kings, William I, b. c.1028, d. Sept. 9, 1087, led the Norman conquest of England and provided stability and firm government in an age of great disorder. The illegitimate son of the Norman duke Robert I, he inherited Normandy in 1035, consolidating his rule in the face of baronial opposition in about 1042. He successfully faced further rebellions and after 1050 began to take an interest in acquiring land in England—perhaps given some encouragement by the English king Edward the Confessor. After Edward's death (Jan. 5, 1066), Vikings under King Harold III of Norway moved on England, and William soon followed with an invasion force of his own. The new English king, Harold II, defeated the Vikings and confronted the Normans near Hastings in October 1066 (see Hastings, Battle of). William's forces achieved a decisive victory, and on Christmas Day 1066, William was crowned king of England, founding the Anglo-Norman monarchy and realm.
A highly capable, intelligent, and determined man, William I established a strongly personal monarchy. He imposed Norman institutions and personnel both on the state and on the church, and he brought England into the mainstream of continental development. Imposing royal authority directly on courts and other institutions, William ordered the inquests that resulted in the monumental Domesday Book. He revolutionized the social, political, and military structures of England, replacing the English nobility with French nobles, thus strengthening his authority, and introducing continental feudalism, a structure in which nobles held land in return for service in the royal army.
As the Anglo-Saxon state was Normanized, so too was the English church: English bishops and abbots were replaced by noted churchmen from the Continent, including Lanfranc of Bec, who became (1070) archbishop of Canterbury. The Conqueror had been a great reformer of the church in Normandy, and he continued this role in England. He established the archbishop of Canterbury as primate of the English church, held reforming councils (which he attended), and exercised not only his rights but also his responsibilities over the church. The bishops were among his closest advisors and officials. William I kept a close but cool relationship with the papacy, supporting ecclesiastical reform while carefully maintaining his control over the English church. He was succeeded as duke of Normandy by his eldest son, Robert II, and as king of England by his sons, first William II, then Henry I.
(Alexander, James W. "William I, King of England (William the Conqueror)." Grolier Multimedia Encyclopedia. Grolier Online, 2012. Web. 1 Feb. 2012.)