"Blanca of Castile, mother of Saint Louis": this is precisely the simplified image that the collective memory of this 13th-century queen has preserved, forgetting that she was a female ruler with an exceptional destiny, like her grandmother, Eleanor of Aquitaine. Blanca, daughter of King Alfonso VIII of Castile and Eleanor of England, born in 1188, at the age of twelve she married the French Prince Louis and received her political education at the court of her formidable father-in-law Philip II Augustus. She became queen in 1223, the mother of twelve children, was widowed at the age of thirty-eight after the death of her husband Louis VIII, and became regent of the kingdom on behalf of her young son Louis IX. Faced with revolts by barons who did not want to be ruled by a woman, the foreign woman, the "Spanish Flu" as she was called at the time, demonstrated unexpected political qualities, a subtle mixture of authoritarianism and flexibility that won the admiration of chroniclers. Blanca was the educator and then the inspirer of the policies of Louis IX of the Saint, who entrusted her with the administration of the kingdom during his participation in the Seventh Crusade. She held a special place in France until her death in 1252, after which she was included in the pantheon of female rulers in national history.