Royal Letters
, i, pp. 244–6 no. CCXI, esp. p. 246. In 1223, Agnes of Beaujeu, the eldest daughter of Guichard of Beaujeu by Sibyl of Hainaut, the sister of Isabella (the first wife of Philip Augustus), and therefore a cousin of Louis VIII, married Count Thibaut (IV) of Champagne: T. Evergates (1999), ‘Aristocratic Women in the County of Champagne’, in idem (ed.),
Aristocratic Women in Medieval France
. Philadelphia, PA: University of Pennsylvania Press, pp. 74–110, at p. 80; C. B. Bouchard (1987),
Sword, Miter and Cloister: Nobility and the Church in Burgundy, 980–1198
. Ithaca, NY: Cornell University Press, p. 294 (Appendix A: Family Trees).