Alan IV, Duke of Brittany of William the Bastard, Duke of Normandy (later to become known as William the Conqueror) support of rebels in Brittany against Alan's maternal uncle, Conan II. Conan II died in late 1066 during a campaign in Anjou, and was succeeded by Alan's parents, Conan's sister Hawise and her husband Hoel II. Hoel ruled as regent from Hawise's death in 1072 until Alan reached his majority in 1084. To prevent further hostilities during his invasion of England, William I married his daughter Constance to the new duke Alan in 1087. The marriage ceremonies may have taken place in Bayeux in Normandy.
William the Conqueror in either late 1039 or October 1040, Gilbert of Brionne took charge of William. Gilbert was killed within months, and another guardian, Turchetil, was also killed around the time of Gilbert's death. Yet another guardian, Osbern, was slain in the early 1040s in William's chamber while the duke slept. It was said that Walter, William's maternal uncle, was occasionally forced to hide the young duke in the houses of peasants, although this story may be an embellishment by Orderic Vitalis. The historian Eleanor Searle speculates that William was raised with the three cousins who later became important in his career