Count of Champagne
Blanche married Theobald III, Count of Champagne, on 1 July 1199 at Chartres, when she was 22-years-old and he was 20-years-old. However, Theobald III died young on 24 May 1201, leaving her pregnant. When she gave birth to a son on 30 May 1201, he immediately became Theobald IV, Count of Champagne (Theobald I of Navarre). Blanche ruled the county as regent until Theobald turned 21 years old in 1222. The regency was plagued by a number of difficulties. Blanche's brother-in-law, count Henry II had left behind a great deal of debt. Henry was the elder son but had transferred the land to his younger brother, Theobald III.