Guillermo fitz Giroie

William fitz Giroie (died 1057), Lord of Échauffour and Montreuil-l'Argillé. A Norman nobleman and patriarch of a large and powerful family in Normandy and Apulia.

Career 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. By her he had a son:

Arnold d'Echaufour

William married secondly, Emma, daughter of Walchelin de Tannei. They had a son:

William of Montreuil, who later in Apulia was called 'the good Norman.'