Yet as a high-minded patriot Dlugosz had no sympathy whatever with Olesnicki's opposition to Casimir's Prussian policy, and steadily supported the king during the whole course of the war with the Teutonic knights.
He was educated at the court of Charles Robert of Hungary, who had married Casimir's beautiful sister Elizabeth, and who gave his brother-in-law an excellent education under Italian masters.
Casimir's last political act was the conclusion of a fresh alliance with Louis of Hungary against Charles IV.
On July 18-20 the combined Swedes and Brandenburgers, 18,000 strong, after a three days' battle, defeated John Casimir's army of ioo,000 at Warsaw and reoccupied the Polish capital; but this brilliant feat of arms was altogether useless, and when the suspicious attitude of Frederick William compelled the Swedish king at last to open negotiations with the Poles, they refused the terms offered, the war was resumed, and Charles concluded an offensive and defensive alliance with the elector of Brandenburg (treaty of Labiau, Nov.
Louis's diplomacy, moreover, was materially assisted by his lifelong alliance with his uncle, the childless Casimir the Great of Poland, who had appointed him his successor; and on Casimir's death Louis was solemnly crowned king of Poland at Cracow (Nov.
Casimir's few wars were waged entirely for profit, not glory.
But provinces are not conquered by manifestoes, and Casimir's acceptance of the homage of the Prussian League at once involved him in a war with the desperate Teutonic Knights, which lasted twelve years, but might easily have been concluded in a twelvemonth had he only been loyally supported by his own subjects, for whose benefit he had embarked upon this great enterprise.
Moreover Casimir's difficulties were materially increased by the necessity of paying for Czech mercenaries, the pos polite ruszenie, or Polish militia, proving utterly useless at the very beginning of the war.
On the death of George, Casimir's eldest son Wladislaus was elected king of Bohemia by the Utraquist party, despite the determined opposition of Matthias Corvinus, king of Hungary, whose ability and audacity henceforth made him Casimir's most dangerous rival.
He encouraged the Teutonic Order to rebel against Poland; he entertained at his court antiPolish embassies from Moscow; he encouraged the Tatars to ravage Lithuania; he thwarted Casimir's policy in Moldavia.
The death of the brilliant adventurer at Vienna in 1490 came therefore as a distinct relief to Poland, and all danger from the side of Hungary was removed in 1490 when Casimir's son Wladislaus, already king of Bohemia, was elected king of Hungary also.
The first symptom of this lawlessness was the separation of Poland and Lithuania, the Lithuanians proceeding to elect Alexander, Casimir's fourth son, as their grand-duke, without even consulting the Polish senate, in flagrant violation of the union of Horodlo.
Casimir's reign of forty-five years was epoch-making for Poland.
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 feature of Casimir's character which most impressed his contemporaries was his extraordinary simplicity and sobriety.
Casimir's married life was singularly happy.