William of Montreuil

William left Normandy for Italy before 1056.[4] At some point he joined forces with Richard I Drengot, who became Prince of Capua in 1058.[5] Richard both adopted William as his son and gave him his daughter's hand in marriage.[5] Richard granted his son-in-law the unconquered counties of Marsia, Campania, and Aquino as part of her dowry, giving William the title of Duke of Gaeta.[6] The prince then ceded control of Gaeta to William, but he soon revolted and attempted to repudiate his wife[lower-alpha 1] after which he planned to marry Duchess Maria, widow of Atenulf I, the former Duke of Gaeta.[7][8] He joined together with Count Atenulf of Aquino,[lower-alpha 2] Lando, Count of Traietto, and Lando's son Peter to free themselves of Prince Richard's control and keep their castles.[9] William obtained some help from friends in Apulia consisting of donations and knights to support him and returned to hold Traetto against the prince.[9] The prince in turn encamped near Traetto across the Garigliano river and for months the two sides engaged in small skirmishes.[9] Finally, short of supplies William and his companions left Traetto for Aquino, where they parted each going his own way.[9] William returned to the castle of Piedimonte trying to gather supplies but with little success.[9]

Prince Richard next acted to break up the coalition between William, Atenulf, Lando and the Duchess Maria.[10] He arranged for Maria to wed his son, Jordan (who he had also made a prince), which offer the duchess readily accepted.[10] Next the prince offered Lando the hand of another daughter, which Lando humbly accepted.[10] He then made Lando Duke of Gaeta in William's place.[7] William was still married to the prince's daughter and by the intercession of William's friends, asked the prince's forgiveness.[10] The prince returned William's wife and heaped riches on him (although there was no further mention of William becoming a duke).[10] It was also at this time the peasants of the castle of Piedimonte rebelled and all the Normans William had left to guard the castle were killed, which disturbed William greatly.[10]

William rebelled against Prince Richard a second time,[lower-alpha 3] apparently emboldened by the lands originally given him by the prince had since been regranted by the pope.[11] William assumed he could count on the pope opposing his master Richard, so he began burning the prince's towns.[11] After suffering this injury to his realm Richard finally sent his son Jordan against William with two hundred and sixty knights.[12] Not being able to locate William or his troops, Jordan and his knights raided William's territories carrying off a great deal of plunder.[12] By this time William had been away at Rome and on his return he asked that the animals be returned to him as they hadn't been plunder, it was robbery[lower-alpha 4] since William had been away at the time.[12] Jordan refused claiming William broke his oath of fealty. William furious with this reply took his eight hundred knights and three hundred infantry and attacked Jordan.[12] According to Amatus, the plunder was abandoned and Jordan and his knights fled the battle after losses on both sides.[12] William then returned to Aquino.[12] Prince Richard then asked for help from Duke Robert in dealing with William, but before anything could be organized it was learned that William had died.[12]

William took up service with Pope Alexander II as commander of his papal forces.[13] He was gonfalonier of the Roman troops, carrying the banner of St. Peter in the conquest of the fertile plains of Campania.[14] The inhabitants were schismatics, a splinter group who had cut themselves off from the Catholic Church.[15] William, by force of arms, compelled them to accept the authority of the church.[15] William, called le bon Normand, was in another expedition at Girona in Catalonia, Spain in charge of troops recruited from Italy and the south of France.[16] An Islamic historian called William de Montreuil the "Captain of the Cavalry of Rome" at the Siege of Barbastro in 1063.[17]

William was, like many of his kinsmen, a benefactor to the Abbey of Saint-Evroul in Normandy.[18] When visited by his father, he sent back a great deal of gifts and money to Saint-Evroul with his father and his companions. William gave to his cousin, Robert de Grandmesnil, former abbot of Saint-Evroul, half the town of Aquino to support him and his monks, the brothers having recently been exiled from Normandy.[15] In September 1068, he granted two churches to Monte Cassino, which is the last record of him.[19] According to the chronicler Amatus of Montecassino, William died in Rome of a "burning fever."[12]