House of Dampierre

While he was in Rome, Joan convinced Margaret to remarry, this time to William II of Dampierre, a nobleman from Champagne.

The disputes regarding the validity of the two marriages and the legitimacy of her children by each husband continued for decades, becoming entangled in the politics of the Holy Roman Empire and resulting in the long War of the Succession of Flanders and Hainault.

The eldest son, John I of Avesnes, who was uneasy about his rights, convinced William of Holland, the German king recognized by the pro-papal forces, to seize Hainaut and the parts of Flanders which were within the bounds of the empire.

The following decades saw further strife between the Dampierres and the Avesnes, who by the start of the 14th century had also inherited the County of Holland and Zeeland.

The main line of the House of Dampierre, originally only counts of Flanders, had managed to inherit the counties of Nevers (1280) and Rethel (1328) through a clever marriage policy.

Through Louis II's mother, a daughter of King Philip V of France, the counties of Artois and Burgundy (the "Franche Comté") were added to this.

Guy in turn gave over the county on his death to his younger son John I from his marriage to his second wife Isabelle of Luxembourg.