William was the second son of
Giroie, Lord of Échauffour and Gisle, daughter of Thurston de Bastembourg lord of
Montfort-sur-Risle. At their father's death in 1033, those properties making up his inheritance went to the eldest son Arnold, while most of the lands Giroie had acquired went to William. When Arnold died from an accidental fall in 1041, William was his heir and, less the smaller holdings that went to his two younger brothers, he inherited most of his father's lands. He headed a powerful family consisting of his brothers, sons, and numerous nephews all of whom were themselves formidable warriors. About 1050, William heard of an old fountain in the forest near a stream called Charenton and went to investigate. He discovered the ruins of an old church dedicated to St. Peter the apostle and surveyed the area for what became the restored
Abbey of Saint-Evroul, so named for its original founder
St. Evroul. In extending his family's wealth and holdings, William had become a vassal of
William I Talvas, Geoffrey de Mayenne, and the
dukes of Normandy. This worked until about 1044 when William fitz Giroie was defending the castle of Montaigu for Geoffrey de Mayenne against William Talvas. Unable to defeat the castle, William Talvas captured Geoffrey de Mayenne and held him prisoner until William Fitz Giroie destroyed his castle of Montaigu. William fitz Giroie immediately razed his own castle to free his lord and in return Geoffrey de Mayenne built fitz Giroie a new castle at
St. Cenery on the river
Sarthe. To avenge this atrocity the sons and kinsmen of William fitz Giroie sacked and destroyed the lands of William Talvas who would not face them in the field. Finally, Talvas' son Arnulf rebelled and exiled his father, now reviled by everyone. He wandered until he was taken in by the de Montgomery family whose son Roger agreed to marry his daughter Mabel in return for the lands William lost. His son, William de Montreuil, had just distinguished himself on his mission for
Pope Alexander II as commander of his papal forces in
Campania and had treasures he wanted to donate to the abbey of Saint Evroul in Normandy. He sent word to them to send a trusted messenger to bring back his gifts for that monastery. When William, now a monk at Bec, heard of the request he volunteered to go to Apulia to meet with his son and bring back the gifts for Saint Evroul. The abbot Theodoric reluctantly agreed to let his friend, now old and blind, to go on this mission accompanied by another monk, Humphrey, Roger of Jumegiès and twelve attendants. They crossed the Alps to Rome, then to Apulia where he met with his son and several of his nephews, family and friends. Intending to stay for some time he dispatched Humphrey to return with a large sum of money. Humphrey reached Rome but was poisoned and robbed of the gold he carried; he died there on December 13, 1056. On hearing this William hastened his departure with another large sum of gold intended for Saint Evroul but got no further than
Gaeta when he became mortally ill. He summoned two knights accompanying them, Ansquetil du Noyer and Théodelin de Tanie, entrusting them to take the gold to Saint Evroul for him. William died shortly afterwards on 5 Feb 1057 and was interred there in the church of Saint Erasmus. ==Family==