He was the son of James of Avesnes and Adela of Guise and brother of Walter, Count of Blois.

In this capacity, he served as tutor and guardian of the young Margaret, sister of Joanna, Countess of Flanders and Hainault.

Philip Augustus, the king of France and victor of Bouvines, then counselled the pope, Innocent III, to declare the marriage of Bouchard and Margaret illegal.

[3] To obtain his release, Margaret accepted the dissolution of the marriage and Bouchard left for Italy to fight for the Holy See.

Bouchard and Margaret had three children, who played an important part in the War of the Succession of Flanders and Hainault: