At the death of their father in 918, Arnulf became Count of Flanders while his brother Adeloft or Adelolf succeeded to the County of Boulogne.[6] However, in 933 Adeloft died, and Arnulf took the countship of Boulogne for himself, but later conveyed it to his nephew, Arnulf II.[7] Arnulf titled himself count by the Grace of God.[8]
In his southern expansion Arnulf inevitably had conflict with the Normans, who were trying to secure their northern frontier. This led to the 942 murder of the Duke of Normandy, William Longsword, at the hands of Arnulf's men.[10] The Viking threat was receding during the later years of Arnulf's life, and he turned his attentions to the reform of the Flemish government. When Dunstan, abbot of Glastonbury, fled into exile, Arnulf received him with honour and lodged him in the Abbey of Mont Blandin, near Ghent.[11]
Count Arnulf died on 27 March 964, allegedly murdered by Heluin in revenge for the murder of William Longsword.
^The Annals of Flodoard of Reims, 919–966, ed. Steven Fanning & Bernard S. Bachrach (University of Toronto Press, CA, 2011), p. xx
^Philip Grierson, 'The Relations between England and Flanders before the Norman Conquest', Transactions of the Royal Historical Society, Vol. 23 (1941), p. 86 n. 1
^Renée Nip, 'The Political Relations between England and Flanders (1066–1128)', Anglo-Norman Studies 21: Proceedings of the Battle Conference 1998, ed. Christopher Harper-Bill (The Boydell Press, Woodbridge, UK, 1999), p. 150
^ abcHeather J. Tanner, Families, Friends and Allies: Boulogne and Politics in Northern France and England, C.879–1160 (Brill, Leiden, Netherlands, 2004) p. 55 n. 143