Background
Gilbert de Brionne was son of Geoffrey de Brionne, Count of Eu (born 962) who was an illegitimate child of Richard I of Normandy.
Gilbert de Brionne was son of Geoffrey de Brionne, Count of Eu (born 962) who was an illegitimate child of Richard I of Normandy.
He was one of the early guardians of Duke William II in his minority. If Lord Brionne would have survived his murder the senior house of de Clare would have probably been known as de Brionne. Lord Brionne was the first to be known by the cognomen Crispin because of his hair style which stood up like the branches of a pine tree.
He inherited Brionne, becoming one of the most powerful landowners in Normandy.
Gilbert was a generous benefactor to Bec Abbey founded by his former knight Herluin in 1031. A number of Norman barons including Ralph de Gacé would not accept an illegitimate son as their leader.
In 1040 an attempt was made to kill William but the plot failed. Gilbert however was murdered while he was peaceably riding near Eschafour.
lieutenant is believed two of his killers were Ralph of Wacy and Robert de Vitot.
This appears to have been an act of vengeance for the wrongs inflicted upon the orphan children of Giroie by Gilbert, and it is not clear what Ralph de Gacé had to do in the business. They would rule over vast lands in modern day Ireland, Scotland, and England and become powerful Marcher Lords who acted independently of the crown.