Gilbert, Count of the Maasgau
Gilbert (Giselbert), Count of Maasgau, was a vassal of Charles the Bald. He is generally described as count of Maasgau on the lower Meuse. This is because the primary document that refers to him calls him "comes Mansuariorum". Mansuaria has however been proposed to be an early Frankish gau in the same general region, probably part of the later Hesbaye.
Gilbert's background is not known. The similarity of his apparent 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.
Children may include:
- Reginar I (c. 850–916). There is no primary source unequivocally stating that Reginar was Gilbert's son.
- Albert is mentioned as a brother of Reginar, probably Reginar I or a relative.
- P. Gorissen "Maasgouw, Haspengouw, Mansuarië" Revue belge de Philologie et d'Histoire Année 1964 42-2 pp. 383–398 
- McKitterick, R. (1983) Frankish Kingdoms under the Carolingians, 751–987 (Longman, London and New York) p. 230.
- Eric Joseph Goldberg, Struggle for Empire: Kingship and Conflict under Louis the German, 817–876, Cornell University Press, 2006
- Rösch, S. (1977) Caroli Magni Progenies (Verlag Degener & Co, Neustadt an der Aisch)
- Halkin, J. and Roland, C. J. (eds.) (1909) Recueil des Chartes de l'abbaye de Stavelot-Malmédy, Tome I (Brussels)