See also
| Husband: | William + FITZOSBERN (1020-1071) | |
| Wife: | Adeliza + of TOSNY (1030-1071) | |
| Children: | Adeliza FITZOSBERN (1048- ) | |
| Emma + FITZOSBORNE (1059-1095) | ||
| Marriage | 1051 | France |
William + FITZOSBERN
| Name: | William + FITZOSBERN | |
| Sex: | Male | |
| Father: | Osbern + of CREPON (990-1035) | |
| Mother: | Emma + of IVRY (1008-1034) | |
| Birth | 1020 | Poitiers, Poitou, France |
| Occupation | Earl of Hereford | |
| Title | Earl of Hereford | |
| Death | 20 Feb 1071 (age 50-51) | Flanders, Belgium |
| Cause: battle wounds at the Battle of Cassel | ||
| Name: | Adeliza + of TOSNY | |
| Sex: | Female | |
| Father: | Roger + of TOENI (990-1038) | |
| Mother: | Godeheut + Adelaide Berenguer BORRELL (995-1066) | |
| Birth | 1030 | Tosni, Eure, Haute-Normandy, France |
| Occupation | Countess of Toeni | |
| Title | Countess de Toeni | |
| Death | 8 Sep 1071 (age 40-41) | Anjou, Isere, Rhone-Alpes, Loire, France |
| Burial | Lire Abbey, France | |
Spouse: John of GRAI
| Name: | Adeliza FITZOSBERN | |
| Sex: | Female | |
| Spouse: | John of GRAI (1033- ) | |
| Birth | 1048 | Normandy, France |
| Name: | Emma + FITZOSBORNE | |
| Sex: | Female | |
| Birth | 1059 | Breteuil, Eure, High Normandy, France |
| Death | 1095 (age 35-36) | |
| Cause: died on the road to Palestine on Crusade | ||
William FitzOsbern (c. 1020 – 22 February 1071), Lord of Breteuil, in Normandy, was a relative and close counsellor of William the Conqueror.
William FitzOsbern became one of the great magnates of early Norman England. He was created Earl of Hereford before 22 February 1067, one of the first peerage titles in the English peerage.
He was the son of Osbern the Steward, a nephew of Duchess Gunnor, the wife of Duke Richard I of Normandy. Osbern became the steward of his cousin Duke Robert I of Normandy, and when Robert left the Duchy to his young son William, Osbern was one of Duke William's guardians. Osbern was killed defending the person of Duke William against an assassination attempt, sometime around 1040.
Osbern had married Emma, a daughter of Count Rodolf of Ivry, who was a half-brother of Duke Richard I of Normandy. Through her he inherited a large property in central Normandy, including the honours of Pacy and Breteuil.
William fitzOsbern was probably raised at the court of his cousin and namesake Duke William, and like his father, became one of the ducal stewards. He was one of the earliest and most vigorous advocates of the invasion of England, and tradition holds that he convinced the doubters amongst the Norman barons of the feasibility of the invasion. He is one of the very few proven Companions of William the Conqueror known to have fought at the Battle of Hastings in 1066.
FitzOsbern's younger brother Osbern was one of Edward the Confessor's chaplains, and possessed the rich church of Bosham in Sussex, and was well-placed to pass along intelligence on the situation in England. He later became Bishop of Exeter.
As Duke William took control of England (becoming William I of England), FitzOsbern was given charge of the Isle of Wight, and then before 22 February 1067 he was made Earl of Hereford as well as Gloucester, Worcester and Oxfordshire.
In any case, that part of England was not yet under Norman control; the understanding must have been that fitzOsbern was to take charge of their conquest when he was able. Also for the central part of 1067 the King returned to Normandy, leaving fitzOsbern, along with Odo of Bayeux, in charge of England.
The King was back in England in 1068, and fitzOsbern accompanied him in the subdual of southwest England. He attended the King's Whitsun court in May, and then himself paid a visit to Normandy, where he fell ill for some months.
In February or March 1069 fitzOsbern was given charge of the new castle at York, but he returned south in time to attend the King's Easter court in April.
Anglo-Saxon resistance in the West Midlands was subdued later in 1069, and it is likely fitzOsbern played a major part in this, though the details are not certain.
During this time fitzOsbern and his followers pushed on into Wales, beginning the conquest of the Welsh Gwent.
As part of the assertion of Norman control over England (and Wales), fitzOsbern was one of the major Norman castle builders. Early castles attributed to him include Carisbrooke on the Isle of Wight and then in South Wales Chepstow (Striguil), Wigmore, Clifford Castle and Monmouth Castle, as well as creating or improving the fortifications of the towns of Hereford and Shrewsbury.
In 1070 trouble arose in Flanders, where King William's brother-in-law Baldwin VI of Flanders had died, leaving his county and his young sons in the hands of his widow Richilde, Countess of Mons and Hainaut. Her control of Flanders was challenged by the brother of her late husband, Robert the Frisian. Looking for help, she offered herself in marriage to fitzOsbern. He could not resist the chance to become also Count of the rich Principality in the German Empire, close to Normandy. He hurried there with his army, but nevertheless was defeated by the Count of Flanders: fitzOsbern lost his life in the Battle of Cassel on 22 February 1071.
FitzOsbern married first Adeliza de Tosny, daughter of Roger I of Tosny. One assumes that he also married Richilde shortly before the Battle of Cassel.
He was succeeded in Normandy by his eldest son, William of Breteuil and in England and Wales by his younger son, Roger de Breteuil. His daughter Emma married Ralph de Gael, 1st Earl of Norfolk. William of Breteuil was held captive and tortured by his daughter's unwelcome suitor, Ascelin Gouel de Perceval 'Lupus', Sire de Yvery, until he finally granted daughter Isabella de Breteuil's hand in marriage to him.
William FitzOsbern lived in Carisbrooke Castle.