Montfort, about midway between Paris and Chartres, styled Montfort-l'Amaury from its founder, gave its name to this family of Montfort.
258 Amauri de Montfort attested charters of Robert I of France in 1022 [Sig. Almaricus miles de Monteforti (H.F., vol. x, p. 607)] and 4 Feb 1031 [Charter for N.-D. de Chartres, Signum Amalrici de Monteforti (Cartul., ed. Lépinois et Merlet, vol. i, pp. 87, 88)]. He is said to have been son of a William of Hainault, who is not otherwise known.
258 He appears to have begun the building of Montfort, described as a 'castrum,' which was completed by his son Simon. He is said to have married Bertrade. The date of his death is unknown. He left two sons and probably a daughter.
258 Cokayne's "Complete Peerage" (Appendix D to v.VII, p.708). He began the building of Montfort. Besides SIMON, he left another son, Mainer, and a dau., Eve, who m. Wiiliam Crispin.
Per "The Dictionary of Royal Lineage", he became baron of Monfort Bretagne in 1003. He is therein referred to as "Amauri II, son of Guilliam, baron of Montfort, who died in 1003". He is said to be descended from Baldwin, count of Flanders and Judith, the daughter of Emperor Charles the Bald.