Amaury was the eldest son of Simon III, lord of Montfort-l'Amaury and count of Évreux, and his wife Matilda.
Amaury retained the county of Évreux and lands in England, but his younger brother Simon (IV) inherited Montfort in Île-de-France.
[3] Amaury married Mabel, the eldest daughter and heiress of William fitz Robert, Earl of Gloucester, and Hawise de Beaumont.
Likewise, there is no evidence that any of William's men ever attached themselves to Amaury's retinue so long as the earldom was controlled by the king.
[1] The obituary of the Cathedral of Évreux mentions his death right after his father's under March 13 without naming the year, specifying that he left the church forty solidi.