Louis IX (1214-1270), or St. Louis, was king of France from 1226 to 1270. One of the greatest French kings, he consolidated the Crown's control over the great lords, proved his passion for justice, and went on two crusades.

Born on April 25, 1214, the oldest of the 12 children of Louis VIII and Blanche of Castile, the half-Spanish Louis IX grew up to be a tall, handsome, blond, and jovial prince. By temperament nervous and energetic, Louis disciplined himself with fasting. His deeply religious mother raised him to be a truly Christian king and, as such, he applied Christian principles to his public acts as well as his private life. Louis was only 12 when he became king; his Spanish mother, in France since she was 12, became regent until Louis could accept active rule at 21.

Louis IX accepted his responsibilities as king with dedication and detachment. He worked to make peace and justice...