At the death of Geoffrey II, his elder son Hugh became Viscount of Châteaudun, while Rotrou probably inherited the family interests around Nogent-le-Rotrou.
[1] After the death of William of Gouët in the late 1050s, Rotrou, with the help of Roger de Montgomery, tried to extend his influence for the strongholds of Perche-Gouët.
However, by 1066, he had become closer to William, the Norman Duke, which can be inferred from the participation of his son Geoffrey in the invasion of England.
[4] Rotrou was quite successful, and able to make substantial donations to religious houses, including St.Vincent of le Mans[1] and his father's foundation of Saint Denis at Nogent-le-Rotrou, where he was able to finish the church.
Rotrou attempted to avenge the murder of his father by attacking Thierry, Bishop of Chartres, an act for which he was briefly excommunicated.