John II Casimir Vasa

John II Casimir Vasa (Polish: Jan II Kazimierz Waza; Lithuanian: Jonas Kazimieras Vaza; 22 March 1609 – 16 December 1672) was King of Poland and Grand Duke of Lithuania from 1648 to his abdication in 1668 as well as a claimant to the throne of Sweden from 1648 to 1660. He was the first son of Sigismund III Vasa with his second wife Constance of Austria. John Casimir succeeded his older half-brother, Władysław IV Vasa.

As a prince, John Casimir embarked at Genoa for Spain in 1638 to negotiate a league with Philip IV of Spain against France, but was captured by Cardinal Richelieu and imprisoned at Vincennes, where he remained for two years. He was released when his brother, Władysław IV Vasa, promised never to wage war against France. John Casimir then travelled extensively throughout Western Europe and entered the order of Jesuits in Rome in 1643. He was made cardinal by Innocent X, but after returning to Poland, he became a layman and succeeded his brother in 1648. His reign commenced amid the confusion and disasters caused by the great revolt of the Cossacks under Bohdan Khmelnytsky in Ukraine, who had advanced into the very heart of Poland. The power of the king had been stripped of almost all its prerogatives by the growing influence of the nobles.

The Tsardom of Russia and Sweden, which had long been active enemies of Poland, renewed their attacks. George II Rakoczy of Transylvania also invaded the Polish territory, and the Sejm was continuously dissolved because of the abuse of the liberum veto law. Charles X Gustav of Sweden triumphantly marched through the country and occupied Kraków in 1655, which forced John Casimir to flee to Silesia. The Swedes were eventually stopped by Stefan Czarniecki under Częstochowa. The wars against the Swedes and the Russians were terminated by treaties involving considerable cessions of provinces on the Baltic and the Dnieper on the part of Poland, which also lost its sway over the cossacks, who placed themselves under the protection of Russian Tsars. During the long battles, John Casimir, though feeble and of a peaceful disposition, frequently proved his patriotism and courage.