Saint Casimir
Polish and Lithuanian prince (1458–1484)
Feast: 4 March (current Roman calendar, optional memorial) · 4 March (1962 Missal, III class)
Who they were
Casimir was born on 3 October 1458 in Kraków Castle, son of King Casimir IV of Poland, Grand Duke of Lithuania, and Elizabeth of Habsburg. At thirteen he was put forward as king of Hungary, but the campaign failed and he withdrew to a life of penance and prayer, formed by his tutor, the historian Jan Długosz.
He still helped his father govern, urging him daily to justice. A contemporary wrote that he wished to be counted among the meek and poor in spirit rather than the powerful, and was father and brother to the poor, orphans and widows. Devoted to the Eucharist and to Our Lady, he died of tuberculosis on 4 March 1484, aged 26, at Grodno, and is buried in Vilnius Cathedral.
The miracles
His brother King Sigismund asked for his canonisation in 1514, and tradition holds that he was canonised around 1521, though no papal bull survives. He is patron of Lithuania.
Why that counted as sanctity
A prince who could have had a crown chose humility, purity and service of the poor, and kept the love of Christ and Mary at the centre of a court life.
- Vatican News - Saint of the day (Italian): Saint Casimir
- Wikipedia - Saint Casimir (canonisation)
- Wikidata Q312057 — dates, feast day and identifiers (CC0)
- English Wikipedia — Saint Casimir (CC BY-SA)
Checked against the sources listed on 21 September 2026. Corrections welcome.