House of Blois chose a wife from the House of Champagne (Adela of Champagne) as a counterpoise to Angevin power. The senior line of the House of Blois became extinct with the death of Joan I of Navarre, wife of Philip IV of France, in 1305. Champagne and Navarre passed to the Capetian dynasty. King Stephen I of England, 1135–1154, was both a member of the House of Blois and the last Anglo-Norman King, being the grandson of William the Conqueror through his daughter Adela of Normandy. A branch of the family was established in Sancerre by Stephen I of Sancerre, a younger
Theobald VI, Count of Blois and Isabelle. The northern part of Blois was erected into the County of Chartres for Isabelle; Margaret received the remainder of the County of Blois, and he sold Clermont to the crown before he died. Theobald VI, Count of Blois Theobald VI of Blois (French: "Thibaut") (died 1218) was count of Blois and Clermont-en-Beauvaisis from 1205 to 1218. He was son of Louis I of Blois and Catherine of Clermont. Theobald married twice: with Maud of Alençon and with Clemence of Roches, but remained childless. Clemence married Geoffrey VI, Viscount of Châteaudun, as her second husband. Theobald fought the Moors