The Montforts were the vassals of the king of France for Montfort and also vassals to the king of England (in their capacity as Dukes of Normandy) for Évreux.
Amaury III had attempted to solve this problem by leaving Évreux to his elder son Amaury IV and Montfort to his younger son Simon III.
Amaury IV accordingly succeeded his father as Count of Évreux, but survived him by only three years, dying unmarried and without children.
He was succeeded his brother, Simon III, reuniting the Montfort titles.
This biography of a French peer or noble is a stub.