Baldwin IV, born c.980, was the son of Arnulf II, Count of Flanders (c 961 - 987) and Rozala of Lombardy (950/60 – 1003), of the House of Ivrea. He succeeded his father as Count of Flanders in 987, but with his mother Rozala as the regent until his majority.
In contrast to his predecessors Baldwin turned his attention eastward, leaving the southern part of his territory in the hands of his vassals the counts of Guînes, Hesdin, and Saint Policy To the north of the county Baldwin was given Zeeland as a fief by the Holy Roman Emperor Henry II, while on the right bank of the Scheldt river he received Valenciennes (1013) and parts of the Cambresis as well as Saint-Omer and the northern Ternois (1120). In the French territories of the count of Flanders, the supremacy of the Baldwin remained unchallenged.
They organized a great deal of colonization of marshland along the coastline of Flanders and enlarged the harbour and city of Brugge.
Baldwin IV died on 30 May 1035.
