 As Robert 's advisor , he pressed the duke to dispute Henry 's claim to the crown of England . The historian David Crouch says that Ranulf " had to provide the strategic vision and energy that Duke Robert lacked " , and other historians have agreed that Ranulf 's arrival was the catalyst to Curthose 's ability to mount an invasion . Ranulf was in charge of organizing transport for the duke 's invasion of England , and also secured the defection of some of Henry 's ships , thus allowing the fleet to land safely . Robert invaded England in July 1101 along with Ranulf , but Robert agreed at the Treaty of Alton on 2 August 1101 to renounce his claim to the English throne . Although no chronicler mentions Ranulf being present at Alton , he probably was there . Ranulf was pardoned in the treaty and restored to his bishopric , but he chose to stay with Robert for five more years . Some historians , including C. W. Hollister , see the treaty as mainly Ranulf 's work , as mainly an attempt to salvage his ecclesiastical career in England , along with a displacement of Ranulf from being the chief councillor of Curthose to merely being one of many . 
