Baldwin II (c. 865 – 10 September 918) was the second margrave (or count) of Flanders, ruling from 879 to 918. He was nicknamed the Bald (Calvus) after his maternal grandfather, Emperor Charles the Bald.
Baldwin II was born around 865 to Margrave Baldwin I of Flanders and Judith, daughter of Emperor Charles the Bald. The early years of Baldwin II's rule were marked by a series of devastating Viking raids into Flanders. By 883, he was forced to move north to Pagus Flandransis, which became the territory most closely associated with the Counts of Flanders. Baldwin constructed a series of wooden fortifications at Saint-Omer, Bruges, Ghent, and Kortrijk. He then seized lands that were abandoned by royal and ecclesiastical officials. Many of these same citadels later formed castellanies which housed government, militia, and local courts.
Between 893 and 899, Baldwin II married Ælfthryth (or Elftrude or Elfrida), the daughter of King Alfred the Great of Wessex. The immediate goal of that Anglo-Flemish alliance was to help Baldwin control the lower Canche River valley. They had four children: Count Arnulf I of Flanders (c. 890–964), Count Adalulf of Boulogne (c. 890–933), Ealswid, and Ermentrud.
Baldwin died on 10 September 918, at Blandijnberg (near Ghent) and was succeeded by his eldest son, Arnulf I of Flanders. His younger son, Adalulf, became the first Count of Boulogne.
More information:
Baldwin II, Margrave of Flanders - Wikipedia