When Louis IX became king of France he was too young to rule. His mother, Blanche of Castile, ruled France on his behalf.

At just twelve years old, upon the death of his father, Louis IX became king of France. Because Louis was too young to rule, France was governed by the queen-mother Blanche of Castile, the widow of Louis VIII. The English believed the time was right to regain lost ground in Normandy, but it would be several years before any expeditions would take place. ^[1]

Louis IX, being twenty-one years old, had the authority to rule France unaided. His mother, Blance of Castile, who had been acting as regent since the death of Louis VIII, still had influence over her son.

While her son, Louis IX of France, was away taking part in the Crusades Blanche of Castile ruled France. She did so until her death in 1252. ^[2]