Relations with Normandy
In the 1050s, Ralph supported King Henry against Duke William II of Normandy. He was present on the king's side at the battle of Mortemer in February 1054, when the Normans routed the royal army. Ralph himself escaped the slaughter and took shelter in the castle of Mortemer. According to Orderic Vitalis, writing about 75 years later, Ralph was aided in his escape by one of the Norman commanders, Roger, castellan of Mortemer, "on account of the fealty he [Roger] had formerly sworn to him [Ralph]." After entertaining Ralph as his guest for three days, Roger escorted him back to his own lands. For this Roger was banished, but soon reconciled, although the castle of Mortemer was never restored to him.
The reason for the oath of fealty is not explained in any primary source. Roger's wife, Hadewisa, however, had inherited the villa of Mers at the mouth of the Bresle, which lay within the diocese of Amiens and may have been under Ralph's suzerainty. The 19th-century historian J. R. Planché has even suggested that Hadewisa was Ralph's daughter.
In 1058, Ralph was with King Henry's army at the siege of Thimert.
In 1063, Ralph's cousin, Walter III of Vexin, died and Ralph inherited the counties of Vexin, with its seat at Mantes, and Amiens. Sometime between 1061 and 1066, Duke William entrusted Hugh de Grandmesnil with the castle of Neuf-Marché, possibly to defend against Ralph after the latter's acquisition of Vexin. Ralph and Hugh fought several skirmishes, and on one occasion, outnumbered, Hugh's army was routed and forced to flee. Then, between 1063 and 1067, Maurilius, archbishop of Rouen, granted the lordship of Gisors, which he held from the duke in Normandy, to Ralph as a life lease. This may have been approved by the duke to assure Ralph's cooperation or non-interference with the upcoming English expedition. Gisors was not restored to Rouen until 1075.
Later, Ralph's relations with Normandy improved and he sent his son Simon to be brought up at William's court. After the Norman conquest of England in 1066, King William returned to Normandy with captives and booty. He held an Easter court at Fécamp on 8 April 1067 to display his spoils and Ralph was in attendance. Ralph then attended the Whitsun court of King Philip I of France in Paris, witnessing a royal charter on 27 May. In June or July, he was again at the king's court in Melun. On either of these occasions, he would have met Bishop Guy of Amiens, whose diocese lay within Ralph's lordship. Ralph, having been to William's celebratory court at Fécamp and having a son raised in the Norman household, was well-positioned to pass along information about the battle of Hastings to the bishop, who began work on his poem Carmen de Hastingae Proelio shortly after.