HERBERT II OF VERMANDOIS WAS A CRUCIAL ALLY of Robert I and Hugh the Great in their struggles against the Carolingians. His progeny included the counts of Flanders and of Blois-Chartres-Champagne and as these lines endured it was difficult for the Capetians to contract durable marriages with these families until the reign of Louis VII; otherwise they were liable to dissolution for consanguinity. Hugh Capet's marriage to Adelaide of Aquitaine had a similar effect.

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