King St. Louis IX was the father of eleven children, born during thirty-six years of marriage, the "Baptized of Poissy" (as he was known), progressively became the Good King Saint Louis (1215-1270). His royal duties contributed to his sanctification, but he, himself, only wanted to follow the example of the King of  Heaven: poor, just, and the servant of all.

THE DIGNITY OF THE BAPTIZED

One day, a lord of the royal court asked King Louis IX, "Sir, why do you always sign things as: Louis de Poissy?" "It is really quite simple!" replied the King. "I respect the chapel where I was baptized even more than the cathedral where I was crowned"
Testimony of de Guillaume de Nangis and de Joinville, cited, among others, in "People of the Saints," in Missel Hosanna, Trady: Paris, 1986, p. 328

THE IMPORTANCE OF GIVING WITNESS IN THE ACT OF FAITH

One day, Louis IX asked hid chronicler, Joinville, "Sénéchal, what was your father's name?" "His name was Simon," Joinville answered. "How do you know this?" queried the King. "I think that I am sure because my mother told me." "Then," replied the King, "you must firmly believe all of the articles of faith given as a testimony by the apostles as you hear them sung each Sunday in the Credo!"
The History of Saint Louis, Jean Sire de Joinville, Desclée de Brouwer, nd, Catholic Faculty, Lille, p.21.