• Born: Between 885 and 890, Flanders
• Married: 934
• Died: 27 Mar 964

  Research Notes:

The Genealogica Arnulfi Comitis names (in order) "Arnulfum, fratrem eius Adelulfum" as the two sons of "Balduinus".

"Arnulfus" is named as son of Count Baudouin II in the Cartulaire de Saint-Bertin, which specifies that he succeeded his father in 918 as ARNOUL I "le Grand" Count of Flanders. "Elstrudis comitissa…cum filiis suis Arnulfo et Adelolfo" donated "hereditatem suam Liefsham…in terra Anglorum in Cantia" to Saint-Pierre de Gand, for the soul of "senioris sui Baldwini", by charter dated 11 Sep 918. Count Arnoul I was responsible for a major expansion of Flemish territory to the south. He and his brother joined the expedition of Raoul King of the Franks against the Normans in 925 and captured Eu. Count Arnoul inflicted a heavy defeat on the Normans in 926. In 932, he seized the abbey of St Vaast, as well as Douai in Ostrevant. In 933, after his brother's death, he seized Boulonnais and Ternois and disinherited his nephews. Count Arnoul made an alliance with Héribert II Comte de Vermandois in 934, which was sealed by his marriage to the latter's daughter. Responding to raids by Guillaume Comte [de Normandie], Count Arnoul invaded Ponthieu and in 939 captured Montreuil from Herluin Comte de Ponthieu, although the county was later recaptured by Comte Guillaume's forces. "Arnulfus…regis…marchysus" restored property to Saint-Pierre de Gand by charter dated 8 Jul 941, signed by "…Baldwini filii Arnulfi marchysi, Isaac comitis, Arnulfi filii eius, Theoderici comitis, Wenemari advocati…". After agreeing to meet Count Guillaume in 942 in order to settle the dispute over Montreuil, Guillaume was murdered, presumably at Count Arnoul's instigation. Count Arnoul was secure in his possession of Montreuil by 949. "Arnulfus Flandrie comes et marchisus" granted use of property "Snellenghem in pago Flandrensi" to Saint-Pierre de Gand, for "uxore mea…Adala atque…filio meo Balduino et filia mea Lietgardis" and for deceased "Balduino genitore meo et Elstrudis genetrice mea atque Heeberto filio meo", and returned "in pago Hainau super fluvio Savo villam…Dulciaca", by charter dated 10 Jul 953. After the death of his son in 962, Count Arnoul was obliged to cede Artois, Ostrevant, Ponthieu and Amiens to Lothaire King of the West Franks in order to ensure the latter's support for the succession of Count Arnoul's infant grandson to the county of Flanders. "Arnulfus marchysus" donated property to Saint-Pierre de Gand by charter dated 5 May 962, signed by "…Baldwini advocati, Theoderici comitis…". "Arnulfus…comes" donated "villam Canlin" to Saint-Pierre de Gand by charter dated 17 Jun 962, signed by "…Balduini advocati…". An undated charter, dated to [962], records the last wishes of "marchysi Arnulfi", noting that "pater meus et mater mea" were buried in the abbey of Saint-Pierre de Gand.

Comte Arnoul was allegedly murdered by Heluin in revenge for the murder of Guillaume I Comte [de Normandie]. The Annales Blandinienses record the death "VI Kal Apr 964" of "Magnus Arnulfus, restaurator huius Blandiniensis coenobii". A charter dated 2 Jul 964 records the donation by "bone memorie Arnulfus marchysus" to Saint-Pierre de Gand, signed by "Odgaudi qui susceptor traditionis fuit…Ingelberti advocati…". ²