His mother, Beatrix, was a sister of Ebles II of Roucy, who had campaigned in Spain in 1073, and Felicia, who married Sancho Ramírez, King of Aragon.

Bishop and lawyer Ivo of Chartres could not resolve it, since it involved a judicial duel, over which the church was not allowed to preside, and so remitted it to the court of the County of Blois.

The reigning pope, Paschal II, who was in Chartres in April, sent the case back to Ivo, who complained in a letter that since "this law of the Church protecting the goods of knights going to Jerusalem was new.

On the first Sunday after returning to France, Rotrou paid a visit to the monastery of Nogent-le-Rotrou, a foundation of his family's and the location of his father tomb.

Rotrou was a direct vassal of Henry in England, where he held fiefs jure uxoris, in right of his wife, the king's daughter Matilda.

He and a group of Normans are said to have fought the Muslims in the service of Alfonso the Battler, then King of Aragon and Navarre, until the Aragonese plotted against them and they returned home.

[10] More probably the Normans just accomplished too little to be noticed, or were perhaps sent back home without encountering any Muslims because their services were not need at the time, when Alfonso the Battler had an alliance with the taifa (faction-kingdom) of Zaragoza.

[11] His parting may have been an act of penitence (perhaps he believed his sins had brought on the tragedy), or perhaps a public demonstration of grieving, since his wife was a daughter of the king, who had also lost his heir, William Adelin, in the wreck.

According to the Chronicle of San Juan de la Peña, Rotrou took part in the conquests of Zaragoza (1118) and Tudela (1119), but this account has been shown to be apocryphal.

[13] Likewise Rotrou is attested fighting for Henry I in Normandy in 1119 and so could not have had any hand in the conquest of Tudela, although the Chronicle of San Juan makes him out to be the chief conqueror and the first and independent ruler of the town.

[16] The Norman lord Robert Burdet, who later held the Tarragona as a principality, may originally have fought alongside Rotrou in Normandy and then followed him to Spain c.1123.

Robert is first mentioned in a charter issued by Rotrou in Spain, in which the count granted some houses in Zaragoza to a knight of his named Sabino in gratitude for his services (December 1124).

[17] This charter also affirms, against the Chronicle of San Juan, that Rotrou ruled Tudela as a vassal of Alfonso the Battler, who is called "emperor" in the document.

Similar charters from February 1128 and November 1131 show that this arrangement continued for almost a decade, even though Rotrou was often absent in Normandy and Robert Burdet in Tarragona.

[19] It has been suggested that Rotrou's rise to an important frontier post in a city in whose conquest he played no role was either recompense for the mistreatment he received in the first decade of the century or due to the deterrent effect of his private army of Normans on the neighbouring Muslims.

[20] In the winter of 1124–25, Rotrou led an expedition against the hilltop Muslim fortress of Peña Cadiella (Benicadell), which guarded the road from Alicante to Valencia.