04 March— Casimir is born in 1458 in Cracovie. The second son of the king, he led Poland from 1479 until 1481 while his father stayed in Lithuania.

His father, who noticed his predisposition to the government, planned to marry him to the daughter of the German Emperor. But having already taken a vow of chastity, Casimir opposed this plan. Even his doctors encouraged him to marry, on the pretext that marriage was a way for him to be cured of his lung disease, but Casimir refused. His father insisted that he take the throne in Hungary, but he declined and was imprisoned for three months.

Pious, virgin, pure, Casimir was particularly charitable with the poor. He died, at only 25 years old, on 04 March 1484 and was canonized in 1522. We proclaim him the patron saint of Poland in 1602.