CASIMIR IV., king of Poland (1427-1492), second son of Wladislaus II. Jagiello, was appointed while still 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., at the battle of Varna. The cause of this long interregnum was the disinclination of the Lithuanians to part with their prince till their outstanding differences with Poland, relating chiefly to the delimitation of the frontiers of the two states, had been settled. Casimir's reign of forty-five years was epoch-making for Poland. He was without doubt one of the greatest statesmen of his age, concealing beneath a simple exterior and homely habits a profound political sagacity and an unerring common-sense, and possessing in a high degree those useful qualities of patience, moderation, and tenacity, which characterized nearly all the princes of the house of Jagiello. Throughout life he steadily followed two guiding principles - the preservation of the political union between Poland and Lithuania at whatever cost, and the recovery of the lost lands of old Poland. It was due entirely to his steadfast adherence to these principles that Poland in the course of the 15th century rose to the rank of a great power; but by a singular irony of fate, Casimir, in consequence of his unswerving efforts to make his country glorious and prosperous, entirely forfeited the popularity of his Polish subjects, whose true interests he understood far better than they did themselves. Thus his refusal to sacrifice Polish to Lithuanian or Lithuanian to Polish interests caused both Poles and Lithuanians to accuse the far-seeing monarch of partiality and favouritism; 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. His difficulties were moreover considerably enhanced by the fact that he was not of an essentially martial temperament, and could not therefore appeal to the heroic side of the Polish character.
The great triumph of Casimir's reign was the final subjugation of the Teutonic Order, a triumph only accomplished after a harassing and desultory thirteen years' war, during which Casimir's own subjects gave him more trouble than all his enemies. The pretext of the rupture was the attempt of the knights to crush the Prussian diet, which, bearing as it did most of the burdens, claimed fairly enough a proportionate share in the government of the Prussian provinces. Excommunicated by the pope and placed under the ban of the Empire, the Prussian cities and gentry naturally turned to their nearest neighbour, Poland, for protection. In October 1453 they placed themselves beneath the overlordship of Casimir; on the 4th of February 1454 formally renounced their ancient allegiance to the Order; and some weeks later captured no fewer than fifty-seven towns and castles. On the 6th of March 1454 Casimir issued a manifesto directing the incorporation of the Prussian provinces with Poland, but granting them at the same time freedom from taxation and full autonomy. But except in the border province of Great Poland, the acquisition of this new territory excited little interest and no enthusiasm in Poland generally. The local diets granted subsidies with a niggard hand, and for the conduct of the war the king soon had to depend almost entirely on Hussite mercenaries, who frequently turned against him when their wages were not paid. The Polish gentry on the other hand exhibited far less energy in the field than in the council chamber; they were defeated again and again by the knights, and showed themselves utterly incapable of taking fortresses. No wonder then if in the earlier years of the war the Order recovered its lost ground, and the king, irritated beyond endurance by the suicidal parsimony of the estates, threatened to retire to the forests of Lithuania. But manlier counsels prevailed, the struggle was resumed, and after the bloody victory of Puck (September 17, 1462) the scales of fortune inclined decisively to the side of Poland. Finally the Holy See intervened, and by the second peace of Thorn (October 14, 1466) all West Prussia, as it is now called, was ceded to Poland, while East Prussia was left in the hands of the knights, who held it as a fief of the Polish crown.
The intervention of the Curia, which hitherto had been hostile to Casimir because of his steady and patriotic resistance to papal aggression, was due to the permutations of European politics. The pope was anxious to get rid of the Hussite king of Bohemia, George Poděbrad, as the first step towards the formation of a league against the Turk. Casimir was to be a leading factor in this combination, and he took advantage of it to procure the election of his son Wladislaus as king of Bohemia. But he would not commit himself too far, and his ulterior plans were frustrated by the rivalry of Matthias Corvinus, king of Hungary, who even went so far as to stimulate the Teutonic Order to rise against Casimir. The death of Matthias in 1490 was a great relief to Poland, and Casimir employed the two remaining years of his reign in consolidating his position still further. He expired rather suddenly while hunting at Troki in Lithuania in June 1492.
The feature of Casimir's character which most impressed his contemporaries was his extraordinary simplicity and sobriety. He, one of the greatest monarchs in Europe, habitually wore plain Cracow cloth, drank nothing but water, and kept the most austere of tables. His one passion was the chase. Yet his liberality to his ministers and servants was proverbial, and his vanquished enemies he always treated with magnificent generosity. Casimir's married life was singularly happy. His consort, Elizabeth of Austria, "the mother of the Jagiellos," bore him six sons and seven daughters, and by her affection and good counsel materially relieved the constant anxieties and grievous burdens of his long and arduous reign.
See Jan Dlugosz, Opera (Cracow, 1887); August Sokolowski, Illustrated History of Poland (Pol.), vol. ii. (Vienna, 1904).
(R. N. B.)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)