Saint Louis IX was the King of France from 1226 to 1270. During his kingship, Saint Louis brought the Kingdom of France into what is now considered the Medieval Golden Age of France. Saint Louis is the only canonized French King.
As King, Saint Louis IX was often regarded by his people as the exemplary Christian leader. Saint Louis was an extremely devout Catholic and oversaw the construction of the Sainte-Chapelle (Holy Chapel) inside the Royal Palace Complexe to house the Crown of Thorns and a fragment of the True Cross. Both relics were acquired when Saint Louis paid the debts of Emperor Baldwin II that were owed to Nicoolo Quirino. The total amount paid was quite large - 135,000 livres where as the amount paid for the entirety of the construction of the Holy Chapel was only 60,000 livres. Saint Louis freqently invited beggars to the Royal Table and would eat only what they left on their plates. Several houses and hospitals were also personally founded by Saint Louis - the House of the Filles-Dieu for reformed prostitutes, the Quinze-Vingt for 300 blind men and hospitals in the towns of Pontoise, Vernon, and Compiegne.
Saint Louis was well known for his many acts of penance, including the wearing of a hairshirt and frequent use of a scourge in private practice. His mercy towards the poor was likewise famous - one story retells that when a young man followed his father in rebelling against the crown, Saint Louis forgave the son despite the court urging his execution, saying "A son cannot refuse to obey his father". In 1230 Saint Louis forbade all forms of ursry within the kingdom and greatly expanded the inquisition within the kingdom. Critically, Saint Louis expanded inquisition activities in the South of France where the the Cathars had settled.
In 1250, while on Crusade in Egypt, Saint Louis was captured and taken prisoner. He recited the Divine Office each day and visited the Holy Land after his release as he hoped to fulfill what he considered the absolute duty of France to be the la Fille ainee de l'Eglise or Eldest Daughter of the Church. In his spiritual testament, written to his son Philip III, he would write:
"My dearest son, you should permit yourself to be tormented by every kind of martyrdom before you would allow yourself to commit a mortal sin."
Saint Louis would die during his second crusade at Tunis on August 25th, 1270. In 1297, Pope Boniface VIII proclaimed the canonization of Saint Louis as the ideal Christian monarch. He is honored as a co-patron of the Third Order of Saint Francis and the Sisters of Charity of Saint Louis was named in his honor. Today his feast day is celebrated in the Roman Catholic Church on August 25th each year.