CASIMIR ,1427-1492), second son of Wladislaus II. Jagiello, was appointed as a lad grand-duke of Lithuania by his father, and crowned king of Poland at Cracow in June 1447, three years after the death of his elder brother, Wladislaus III. Throughout life Casimir aimed at the preserva tion of the union between Poland and Lithuania, and the recovery of the lost lands of old Poland. Owing to his steadfast adherence to these principles Poland in the 15th century became a great power, but his essential unwarlikeness, and his impartiality be tween the two countries over which he ruled made him unpopular with both ; while his anti-German policy, on which the future safety of the dual state depended, could only be carried through by the most humiliating concessions to patrician pride and greed. By confirming, under threat of deposition, the privileges of the nobles, he established the disastrous principle of elective mon archy in Poland. He also acquiesced when the senate decreed that the king was not to make war without their permission.
He finally subjugated the Teutonic Order of ter a 13 years' war, during which his subjects troubled him more than his en emies. In Oct. 1453 the Prussian cities and gentry, in dispute with the Order, which had been excommunicated by the Pope and banned by the Empire, placed themselves beneath the over lordship of Casimir; on Feb. 4, they renounced their allegi ance to the Order, and captured 57 towns and castles. On March 6, 1454, Casimir incorporated the Prussian provinces with Po land, with a guarantee of autonomy and of freedom from taxa tion. This aroused little enthusiasm in Poland, and the Order gradually recovered ground from the incompetent Polish gentry. The king, irritated by the suicidal parsimony of the estates, threatened to retire to Lithuania, but after the bloody victory of Puck (Sept. 17, 146 2) fortune favoured Poland. Finally the Holy See intervened, and by the second peace of Thorn (Oct. 14, 1466) all West Prussia was ceded to Poland, while East Prussia was held by the knights as a fief of the Polish crown.
Casimir had previously profited by the rivalry of two popes to acquire the right of appointment of bishops by the Crown ; and his resistance to papal claims had naturally caused hostility at Rome. The Curia changed sides in order to enlist Casimir against the Turks. Casimir took advantage of this to get his son Wladis laus made king of Bohemia instead of the Hussite Podebrad. But his ambitions were frustrated by Matthias Corvinus, king of Hun gary, who roused the Order against him. Casimir died in June 1492.
Casimir founded the Polish diet in 1467, and his reign was a Golden Age of culture for Poland. Public schools were estab lished for citizens, serfs and nobles. There was liberty of opin ion and of the press, and the many printing presses published books banned elsewhere. Poland was a refuge of scholars, and Copernicus came to Cracow in 1492.