Mary married Alphonso of Brienne about 1250.[2] She became Dame d'Issoudun, Countess of Eu and of Guinness in 1250. Mary died on October 1, 1260 in Melle.[2]
↑ 1.01.1George Edward Cokayne, The Complete Peerage of England, Scotland, Ireland..., Vol. V, eds. H. A. Doubleday; Howard de Walden (London, The St. Catherine Press, Ltd., 1926), p. 167
↑ 2.02.12.2Detlev Schwennicke, Europaische Stammtafeln: Stammtafeln zur Geschichte der Europaischen Staaten, Neue Folge, Band III Teilband 4 (Marburg, Germany: J. A. Stargardt, 1989), Tafel 683
↑George Edward Cokayne, The Complete Peerage of England, Scotland, Ireland..., Vol. V, eds. H. A. Doubleday; Howard de Walden (London, The St. Catherine Press, Ltd., 1926), p. 170