Gilbert's background is not known. The similarity of his son's name to the name "Ragnar" has been used as an argument to suggest a Viking connection. Another possibility is that he was related to a man named Reginar, son of Meginhere (a nobleman from the court of Charlemagne). Gilbert had served King Lothair I, but defected to Lothair's half-brother Charles the Bald during the civil war of 840-843. Gilbert's lands eventually came under the rule of Lothair and his rights as count were revoked. In 846 Gilbert abducted an unnamed daughter of Lothair and his wife Ermengarde of Tours. He took her to Aquitaine and married her in an attempt to force Lothair to reinstate him. Rösch suggests that Gilbert's wife was named Ermengarde, but there is no conclusive evidence that this is correct.
|Offspring of Gijsbert and Irmgard (c830-849)|
|Regnier I de Hainaut (c850-915)||850||915 Meerssen|| Hersinde (?-aft916)|