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
John IV, Duke of Brittany John IV, Duke of Brittany John IV the Conqueror KG (in Breton Yann IV, in French Jean IV, and traditionally in English sources both John of Montfort and John V) (1339 – 1 November 1399) was Duke of Brittany and Count of Montfort from 1345 until his death and 7th Earl of Richmond from 1372 until his death. He was the son of John of Montfort and Joanna of Flanders. His father claimed the title Duke of Brittany, but was largely unable to enforce his claim for more than a brief period. Because his father's claim to the title was