Baldwin was the eldest son of Baldwin V of Flanders and Adela, a daughter of King Robert II of France[1][2] and Constance of Arles.
[3] His father arranged his marriage, under threat of arms, to Richilde, the widow of Herman of Mons and heir of Hainaut.
[4] As Hainaut was a part of the Holy Roman Empire this enraged Emperor Henry III, who had not been consulted, causing him to wage war on the two Baldwins without success.
[4] Between 1050 and 1054 Count Lambert II of Lens fought alongside the Baldwins against Henry III finding that this alliance best protected his interests.
[6] His early death left Flanders and Hainaut in the hands of his young son, Arnulf III, with Richilde as regent.