The third child of King Casimir IV of Poland, St. Casimir grew up under the tutelage of John Dlugosz, a learned and devout canon of Cracow. Dlugosz trained Casimir in piety from age nine, so the youth developed a hearty Christian character. He avoided all softness and self-indulgence and at the same time related to everyone cheerfully and compassionately.
If we scrape away the thin coat of sweetness from Casimir’s biography, we meet a young man of real integrity and courage. Here is an excerpt:
It is difficult to imagine or to express his passion for justice, his exercise of moderation, his gift of prudence, his fundamental spiritual courage and stability, especially in a most permissive age, when men tended to be headstrong and by their very natures inclined to sin. Daily he urged his father to practice justice throughout his kingdom and in the governance of his people; and whenever anything in the country had been overlooked because of human weakness or simple neglect, he never failed to point it out quietly to the king. He actively took up the cause of the needy and unfortunate and embraced it as his own; for this reason the people called him the patron of the poor. Though the son of a king and descendant of a noble line, he was never unapproachable in his conversation or dealings with anyone, no matter how humble or obscure. He always preferred to be counted among the meek and poor of spirit, among those who are promised the kingdom of heaven, rather than among the famous and powerful men of this world. He had no ambition for the power that lies in human rank and he would never accept it from his father. He was afraid the barbs of wealth, which our Lord Jesus Christ spoke of as thorns, would wound his soul, or that he would be contaminated by contact with worldly goods. Many who acted as his personal servants . . . testify that he preserved his chastity to the very end of his life.
As a young man, Casimir already had the strength to stand up to his father. Once at the request of Hungarian nobles, the king sent Casimir, then barely fifteen years old, at the head of an army against King Matthias Corvinas. When the Hungarian nobles abandoned the cause and Casimir’s men began to desert, he bravely defied his father’s instructions and retreated. And, wisely, he had backed out at a moment when the Turks were threatening to advance against Europe’s eastern borders. Feeling disgraced, however, the king punished his son by confining him at Dobzki castle for three months. But from that time Casimir tenaciously refused to participate in war. Thus his Polish and Lithuanian admirers esteem him as “The Peacemaker.”
Casimir had no inclination to politics, but he always involved himself on behalf of his father’s impoverished subjects. When his father promoted a strategic marriage between him and a daughter of the emperor, he refused because of his commitment to celibacy. Weakened by his asceticism and afflicted with lung disease, Casimir died in 1484. He was only twenty-three years old.