Roger I of Tosny Fécamp Abbey were installed. This monastery was one of the first baronial foundations in Normandy The foundation charter reveals that the lord of Tosny gave it a small possession around Conches and his forest. In 1035, Robert I's death began a troubled period in the duchy of Normandy. Civil wars multiplied and Roger (whose relations with his neighbours was already argumentative) was one of the main players in them. According to the Norman chroniclers, the lord of Tosny refused to serve the new duke, the future William the Conqueror, due to his being a bastard. He especially took advantage of
Guy, Duke of Sorrento forever loyal to the Hauteville leadership, however. In 1073, he captured the rebel Herman, his own nephew, and handed him over to Robert Guiscard, his nephew-in-law. Guy died amidst the breakup of the great principality his brother had forged and he had preserved. With his death, Sorrento became independent once more. His children were: Guy, Duke of Sorrento Guy (; born c. 1012) was the duke of Sorrento from 1035, the brother of Guaimar IV of Salerno, father-in-law of William Iron Arm and William of the Principate, and brother-in-law of Humphrey of Hauteville. He was the son of Guaimar III