William Fitz-Osbern was the principal agent in preparing for the invasion of England.
Background
William was the son of the Norman knight Osburn, the seneschal and cousin of Normandy Duke Robert II. After the death of Robert II his young son Wilhelm became the duke. After that the seneschal Osburn became one of his guardians. In 1040, Osburn was killed in the defense of the young Duke of the conspirators. The father's place at the court of William was taken by his son Guillaume, who inherited from his mother the lords Pasi and Breteuil.
Career
Fitz-Osbern was one of the leaders of the army of the Duke of Wilhelm, that landed on the English coast at the end of September 1066. He also participated in the Battle of Hastings. When in the spring of 1067 King William went to Normandy, William Fitz-Osbern, together with Bishop Bayeux Odo, was entrusted to run England. The main task of Fitz-Osbern was to organize the defense of the eastern regions of the country in order to prevent a possible Danish invasion. It was in Denmark that many Anglo-Saxon aristocrats took refuge, and Danish king Sven Estridsen himself maintained claims to the throne of England. The residence of Fitz-Osbern was Norwich. The Danish fleet arrived, but only in the autumn of 1069, and thanks to the defense system organized by William, the Danes could not land in East Anglia. In the future, William Fitz-Osbern remained close associate of King William, regularly participated in meetings of the Grand Royal Council and the Norman campaigns to the north. As Earl of Hereford, William Fitz-Osbern became the creator of a new defense system in western England. Along the Welsh border, he built a number of castles: Monmouth, Carisbrook, Chepstow and Wigmore, which closed the way from South Wales to England. Moreover, the count was able to establish British power in Gwent, one of the Celtic kingdoms of southeastern Wales. The authority and influence of the Fitz-Osbern was especially evident in 1070, when the dying Count of Flanders Baldwin VI appointed William the guardian of his minor heir. The second guardian was King Philip I. of France. However, soon after the death of Baldwin VI in Flanders, an uprising broke out against the reign of the widow of the deceased Count Rischilda of Genshauska. At the head of the rebels stood brother Baldwin, Robert Freese. Rishilda turned to William Fitz-Osbern for help and offered him her hand and heart. At the end of 1070 William with a small army landed in Flanders, but on February 22, 1071, the Anglo-Norman troops were defeated in the battle of Kassel, and Earl Hereford himself was killed. The failure of the Flanders expedition of William Fitz-Osbern sharply complicated the Anglo-Flemish relations.
Achievements
Connections
William was married to Adelize de Tosni, they had two sons.