Instability and defections
By 1089, Duke Robert faced another threat in the form of Rufus's wish to destabilize Normandy. In contrast to his elder brother, the English king possessed deep pockets and more expansive methods of raising wealth, with a large treasury available at Winchester. William bribed many of Robert's vassals away from him, starting with the garrison of Saint-Valery. Stephen of Aumale, Gerard of Gournay, Robert of Eu, Walter Giffard, and Ralph Mortemer were all coaxed towards William's side, leaving most of the Norman barons on the right bank of the Seine ready to break away from the duke.
Lacking the same financial resources or ability to deliver reward, Robert was in a sense helpless against this change, but Helias of Saint-Saëns, the Lord of Saint-Saëns, stood firm in the duke's camp. Helias was, for his loyalty, given the hand of an illegitimate daughter of Robert's alongside the castles of Arques and Bures, making him one of the only counterbalances to William's intercessions in the region. The duke managed to form an alliance with Philip, King of France against the magnates East of the Seine, and they launched a siege of Gerard of Gournay's castle at La Ferté-Bernard. In exchange, Robert granted Philip the castle of Gisors, along the Epte, which marked the border of the Vexin. The castle had belonged to the Cathedral of Rouen and this grant angered Archbishop William. Robert besieged and captured the castle of Eu, and Aird considers him to have had a successful campaign against the rebels by September of 1089.
A revolt broke out in Maine when the Manceau heard of Robert's illness in late 1089. Preoccupied with the barons east of the Seine, Robert met with Fulk IV, Count of Anjou, and requested that he resolve the crisis. Fulk agreed if he was allowed to marry the daughter of Simon de Montfort, Bertrade, despite having been married thrice. Bertrade was in the care of her uncle, William of Évreux, and to secure the marriage, Robert had to grant William the lands of Ralph Asshead, and grant a series of castles to his nephew, William of Breteuil. Fulk successfully suppressed the revolt in Maine for a year.
In November 1090, a revolt broke out in Rouen led by the Pilatenses, a faction of the city opposed to Robert's rule and led by Conan, the son of Gilbert Pilatus. As supposedly the wealthiest citizen of Rouen, Conan was supported by William Rufus in his revolt, and Robert had to hastily summon his vassals to assist him in crushing the riot. Henry, Robert's brother, was convinced to forget the duke's prior wrongs against him and come to his aid. Though he led his men bravely, Duke Robert's vassals convinced him to flee the city for his own safety, while Henry and Gilbert of L'Aigle crushed the revolt and captured many of its leaders. Conan was personally executed by Henry.
But Robert's success here did not prevent failures elsewhere. In the same month, a private war broke out between Ralph of Conches and William of Évreux, and Ralph appealed to the duke for aid. Robert, under significant pressure, was not forthcoming, and Ralph then requested support from William of England. William quickly directed his satellites in Normandy to support Ralph, thus expanding the king's influence in the duchy. At the same time, in Maine, the Norman garrisons were expunged and Maine was claimed by Hugh of Este, a relative of Hugh IV. Only Hoël, Bishop of Le Mans stayed loyal to Robert and his resistance saw support for Hugh ultimately deteriorate. Hugh would ultimately sell the comital title to Helias of La Flèche.