Jeanne was only two or three when both of her parents died overseas in Constantinople and she and her sister were shuttled from one guardian to another, finally ending up in the care of the King of France, Phillip Augustus. When she was ten, around the time her sister Jeanne married and moved to take control of Flanders and Hainaut, Marguerite married Bouchard of Avesnes, a nobleman from Hainaut without her sister’s permission. The couple stayed married for nine years and had two sons
Sometime after her marriage, Marguerite fought with her sister and Jeanne tried to force the couple to separate. She was successful and Marguerite remarried William of Dampierre. This marriage produced three sons and at least one, maybe three daughters. Marguerite’s involvement in what some considered bigamous marriages along with the fact that she had sons by two different fathers eventually led to conflict. The Avesnes sons fought the Dampierre sons for two years and even Louis IX’s intervention, giving Flanders to the Dampierres and Hainaut to the Avesnes,* only quieted it for a few years.
In terms of economic and religious policies, Marguerite very much followed and expanded on her sister’s work. She worked to expand the cities’ power and increase international trade. She supported the beguines and the Cistercians in particular founding communities and making laws to protect their members. When she died in 1280, she left her grandson John of Avesnes count of Hainaut and her son William of Dampierre count of Flanders.
*Technically he may not have had the right to make those decisions, but he did and it worked. For a short time anyway.