He took the part of Count William of Évreux during his private war with Raoul II, lord of Conches.
As Richard had no children at the time of his death, the lordship passed to his brother Simon II.
[1] Upon the death of his father in 1087 and his half-brother Amaury II in 1089, he succeeded them as the lord of Montfort-l'Amaury.
In this dispute, Richard took the side of William of Évreux and was killed while raiding St Pierre Abbey (Abbaye Saint-Pierre) in Conches in November 1091.
Dying childless, he left the lordship of Montfort to his brother Simon II.