William the Conqueror King Henry in a campaign against him, the last known cooperation between the two. They succeeded in capturing an Angevin fortress, but accomplished little else. Geoffrey attempted to expand his authority into the county of Maine, especially after the death of Hugh IV of Maine in 1051. Central to the control of Maine were the holdings of the Bellême family, who held Bellême on the border of Maine and Normandy, as well as the fortresses at Alençon and Domfront. Bellême's overlord was the king of France, but Domfort was under the overlordship of Geoffrey Martel and Duke William was Alençon's
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