He is the glorious King of France who was born at Poissy in 1215. He died fighting in one of the crusades to regain the Holy Land for Christians when he was only fifty-five years old. Saint Louis is the king who started the custom of genuflecting during the Mass when the priest said of the Son of God in the Creed: Et Homo factus est (And [He] was made Man). Saint Louis fought in two crusades, the last two. He redeemed the Crown of Thorns of Our Lord from the Venetians and built a beautiful chapel for it in Paris, called Sainte Chapelle. All of Saint Louis’ relics were destroyed by the Masons and the Jews during the French Revolution. But his memory will never die in France, nor in the whole Catholic Church. The city of Saint Louis, Missouri, was named for him by early American Catholics who came from France.
Read more about him in a longer article by Gary Potter: Louis IX: King, Crusader, and Saint.