Casimir IV KG ( 30 November 1427 – 7 June 1492) of the Jagiellonian dynasty was Grand Duke of Lithuania from 1440, and King of Poland from 1447, until his death.
He was one of the most active Polish rulers, under whom Poland, by defeating the Teutonic Knights in the Thirteen Years’ War recovered Pomerania, and the Jagiellonian dynasty became one of the leading royal houses in Europe.
He was a strong opponent of aristocracy, and helped to strengthen the importance of Parliament and the Senate.
The great triumph of his reign was the effective and final destruction of the Teutonic Order, which brought Prussia under Polish rule.
The long and brilliant rule of Casimir corresponded to the age of “new monarchies” in western Europe. By the 15th century Poland had narrowed the distance separating it from western Europe and become a significant factor in international relations.
The demand for raw materials and semi-finished goods stimulated trade, producing a positive balance, and contributed to the growth of crafts and mining in the entire country.
He was a recipient of the English Order of the Garter (KG), the highest order of chivalry and the most prestigious honour in England and of the United Kingdom, awarded at the Sovereign’s pleasure as his or her personal gift, on recipients from the United Kingdom and other Commonwealth realms.
Casimir Jagiellon was the third and youngest son of King Władysław II Jagiełło and his fourth wife, Sophia of Halshany. His father was already 65 at the time of Casimir’s birth, and his brother Władysław III, three years his senior, was expected to become king before his majority.
Strangely, little was done for his education; he was never taught Latin, nor was he trained for the responsibilities of office, despite the fact he was the only brother of the rightful sovereign.
He often relied on his instinct and feelings and had little political knowledge, but shared a great interest in the diplomacy and economic affairs of the country.
Throughout Casimir’s youth, Bishop Zbigniew Oleśnicki was his mentor and tutor, however, the cleric felt a strong reluctance towards him, believing that he would be an unsuccessful monarch following Władysław’s death.
The sudden death of Sigismund Kęstutaitis left the office of the Grand Duchy of Lithuania empty. The Voivode of Trakai, Jonas Goštautas, and other magnates of Lithuania, supported Casimir as a candidate to the throne. However many Polish noblemen hoped that the thirteen-year-old boy would become a Vice-regent for the Polish King in Lithuania.
Casimir was invited by the Lithuanian magnates to Lithuania, and when he arrived in Vilnius in 1440, he was proclaimed as the Grand Duke of Lithuania on 29 June 1440 by the Council of Lords, contrary to the wishes of the Polish noble lords—an act supported and coordinated by Jonas Goštautas.
When the news arrived in the Kingdom of Poland concerning the proclamation of Casimir as the Grand Duke of Lithuania, it was met with hostility, even to the point of military threats against Lithuania.
Since the young Grand Duke was underage, the supreme control over the Grand Duchy of Lithuania was in the hands of the Council of Lords, presided by Jonas Goštautas. Casimir had been taught Lithuanian language and the customs of Lithuania by appointed court officials.
During Casimir’s rule the rights of the Lithuanian nobility—dukes, magnates and boyars (lesser nobles), irrespective of their religion and ethnicity—were put on an equal footing to those of the Polish szlachta.
Additionally, Casimir promised to protect the Grand Duchy’s borders and not to appoint persons from the Polish Kingdom to the offices of the Grand Duchy.
He accepted that decisions on matters concerning the Grand Duchy would not be made without the Council of Lords’ consent. He also granted the subject region of Samogitia the right to elect its own elder. Casimir was the first ruler of Lithuania baptised at birth, becoming the first native Roman Catholic Grand Duke.
Casimir succeeded his brother Władysław III (killed at the Battle of Varna in 1444) as King of Poland after a three-year interregnum on 25 June 1447.
In 1454, he married Elisabeth of Austria, daughter of the late King of the Romans Albert II of Habsburg by his late wife Elisabeth of Bohemia. Her distant relative Frederick of Habsburg became Holy Roman Emperor and reigned as Frederick III until after Casimir’s own death.
The marriage strengthened the ties between the house of Jagiellon and the sovereigns of Hungary-Bohemia and put Casimir at odds with the Holy Roman Emperor through internal Habsburg rivalry.
That same year, Casimir was approached by the Prussian Confederation for aid against the Teutonic Order, which he promised, by making the separatist Prussian regions a protectorate of the Polish Kingdom. However, when the insurgent cities rebelled against the Order, it resisted and the Thirteen Years’ War (1454–1466) ensued.
Casimir and the Prussian Confederation defeated the Teutonic Order, taking over its capital at Marienburg (Malbork Castle). In the Second Peace of Thorn (1466), the Order recognized Polish sovereignty over the seceded western Prussian regions, Royal Prussia, and the Polish crown’s overlordship over the remaining Teutonic Monastic State, transformed in 1525 into a duchy, Ducal Prussia.
Elisabeth’s only brother Ladislaus, king of Bohemia and Hungary, died in 1457, and after that Casimir and Elisabeth’s dynastic interests were directed also towards her brother’s former kingdoms.
King Casimir IV died on 7 June 1492 in the Old Hrodna Castle in the Grand Duchy of Lithuania, which was in a personal union with Poland.
The remains of King Casimir IV and his wife Elisabeth were interred in a tomb situated in the chapel of the Wawel Castle in Kraków, Poland. With the consent of then Cardinal Karol Wojtyła (Archbishop of Kraków, who became Pope John Paul II), a team of scientists was given permission to open the tomb and examine the remains, with restoration as the ultimate objective. Casimir’s tomb was opened on Friday, April 13, 1973.
Twelve researchers were present. Inside the tomb they found a wooden coffin that was heavily rotted. It contained what was left of the king’s decayed corpse.
Within a few days, four of the twelve scientists and researchers had died. Not long after, there were only two survivors: Dr. Bolesław Smyk, a microbiologist, and Dr. Edward Roszycki. Smyk was to suffer problems with his equilibrium for the next five years.
In the course of his microbiological examinations, Dr. Smyk found traces of fungi on the royal insignia taken from the tomb.
He identified three species – Aspergillus flavus, Penicillim rubrum, and Penicillim rugulosum. These fungi are known to produce aflatoxins that can be deadly when in contact with skin and inhaled into the lungs.