The last is sometimes reckoned a misnomer, as he is not called Robert the Devil in surviving contemporary accounts and the name seems to have been a conflation of the historical figure with a separate fictional one during the late Middle Ages.

Robert was the son of Richard II of Normandy and Judith, daughter of Conan I, Duke of Brittany, and Ermengarde-Gerberga of Anjou.

Private wars raged between neighbouring barons, which resulted in a new aristocracy arising in Normandy during Robert's reign.

[5] Robert also attacked another powerful churchman, his cousin Hugo III d'Ivry, Bishop of Bayeux, banishing him from Normandy for an extended period of time.

[10] His cousins, the Athelings Edward and Alfred, sons of his aunt Emma of Normandy and Athelred, King of England, had been living at the Norman Court and at one point Robert, on their behalf, attempted to mount an invasion of England but was prevented in doing so, it was said, by unfavourable winds,[11] that scattered and sank much of the fleet.

Gesta Normannorum Ducum stated that King Cnut sent envoys to Duke Robert offering to settle half the Kingdom of England on Edward and Alfred.

[15] According to the Gesta Normannorum Ducum he travelled by way of Constantinople, reached Jerusalem, fell seriously ill and died[a] on the return journey at Nicaea on 2 July 1035.

[17] Permission was granted but, having travelled as far as Apulia (Italy) on the return journey, the envoys learned that William himself had meanwhile died.