• Born: Between 900 and 905, Rouen, Seine-Maritime, Haute-Normandie, France
• Married (1): Abt 932, Normandy, France
• Married (2): Abt 935, Normandy, France
• Died: 17 Dec 942, France

  Research Notes:

William I "Longsword".

Guillaume de Jumièges records that Rollo captured “Baiocasensem urbem” [Bayeux] along with "nobilissimam puellam...Popam filiam...Berengarii illustris viri" whom he married “more Danico” and by whom he had “Willelmum...filiamque...Gerloc”. However, the Planctus for William Longsword, composed shortly after the murder of Guillaume, states that he had a Christian mother of overseas origin. Orderic Vitalis names "Willelmum cognomento Longam-Spatam" as the son of “Rollo dux” by his wife “Berengarium comitem...Popam...filiam eius”. Dudo of Saint-Quentin states that he was born in Rouen and, in a later passage, describes him as a "young man" one year before his father's death. His birth date is estimated based on the estimated birth date of his own son. His father chose him as heir one year before his death. Flodoard records that "filius Rollonis" did homage to ex-king Charles III "le Simple" at "castellum…Auga" in 927.

He succeeded his father in [928/33] as GUILLAUME I "Longuespee" Comte [de Normandie]. Flodoard names "Willelmus princeps Nortmannorum" in 933. Dudo of Saint-Quentin records that he quelled a rebellion led by the Viking chief Riulf after the latter besieged Rouen. In return for swearing allegiance to Raoul King of France, Guillaume appears to have been granted rights to further territory along the coast in 933, maybe the Cotentin and Avranchin. If this is correct, it would have created rivalry with the dukes of Brittany. Dudo of Saint-Quentin describes Comte Guillaume's invasion of Brittany shortly after his accession to quell a rebellion against him, and his defeat of the rebels at Bayeux. Responding to raids by Comte Guillaume, Arnoul I Count of Flanders invaded Ponthieu and in 939 captured Montreuil from Herluin Comte de Ponthieu, although it was recaptured by Comte Guillaume's forces. Guillaume of Jumièges records that “Arnulfus Flandrensis comes” captured "castrum...Monasteriolum" from “comiti...Herluino”, who sought help from “Normanniæ dominum” who recaptured the castle for Herluin. In 939, Guillaume joined the alliance against Louis IV King of France which was led by Otto I "der Große" King of Germany who raided Frankish territory. Comte Guillaume, however, met King Louis at Amiens, receiving a confirmation of the grant of his lands in Normandy. Guillaume of Jumièges records that “Arnulfus Flandrensis” tricked "duci Willelmo" into a meeting to settle the dispute concerning Montreuil “apud Pinchiniacum”, where Guillaume was killed by “Henricus necnon Balzo, Robertus quoque atque Ridulphus quatuor diaboli filii” on “XVI Kal Jan” 943.

Orderic Vitalis records that "Willelmus dux" was killed in 942 “fraude Arnulphi Flandrensis satrapæ”. The Annalibus Rotomagensibus record that "Willermus dux Normannorum filius Rollonis" was killed "943 XVI Kal Jan". The Brevis Relatio de Origine Willelmi Conquestoris records that "Rollo et Willelmus filius eius" were buried "apud Rothomagum in ecclesia beatæ Mariæ". Orderic Vitalis implies that the transfer of his body to Rouen Cathedral took place after the "the ninth year" in office of Archbishop Maurilius, who had succeeded Mauger de Normandie, which would date the event to [1064]. ¹