I'm trying to figure out whether this is a gratuitous Monty Python reference or not. As I describe St. Casimir, Prince of Poland, picture Herbert, the prince in Swamp Castle; judge whether the comparison is apt. Don't remember the scene? Watch it here.
Casimir was the son of Casimir IV, King of Poland. He was sent at age thirteen at the head of an army to the Hungarian border, which he was supposed to cross in triumph, Hungary from an unpopular monarch and claiming the throne for himself. The Hungarian King, Matthias Corvinus, raised an army to defend his throne against the Poles. The Polish army had not been paid, so they took off and left the boy prince to his own devices. Upon returning to his dad, he was locked in the castle of Dobzki until some use could be found for him.
King Casimir negotiated a marriage to the daughter of Frederick III, the Holy Roman Emperor, but young Casimir thought not. By this point, he had settled on a life of celibacy. [No word on whether King Fred's daughter had "huge tracts of land."]
Singing? Yeah, he's got that too. "Omni die dic Mariae" is a hymn written by Bernard of Cluny in the 12th century; he sang it so much it is often identified as his own work. He even asked that a copy of it be included in his coffin. It was placed under his head following his death from tuberculosis at age twenty-six.