CASIMIR, IV. was the second eon of Jagollo, grand duke of Lithuania, who married Hedwigo, daughter of King Lewis, and thus became king of Poland under the name of Wladislas IV. Casimir succeeded to the crowns of Poland and Lithuania after the death of his brother Wladislas V., who lost his life in the battle of Varna against the Ottomaus in 1444. Casimir made war against the Teutonic knights, and took from them a great part of Prussia; upon which the grand master of tho order acknowledged himself a vassal to the crown of Poland. The duke of Wallachia also about the same time made allegiance to the Polish crown. It was under Casimir that the deputies of the provinces first appeared at the Diet of the kingdom. of Poland. (PuffendorL) This was the epoch of the greatest splendour of that country. Wladislas, son of Casimir, was made king of Bohemia and of Hungary. Casimir died in 1492, and was succeeded by his second son John Albert. It was Casimir who enforced the use of Latin as the official language of Poland.
CASLMIlt V., son of Sigiamund III., was elected king of Poland after the death of his brother Wladislas VII. iu 1647. Casimir was then at Rome, where he had entered the church, and had become a cardinal. Having obtained a dispensation from the pope, ho married Luisa Maria Gonzaga, his brother's widow. Ile made war against the Cossacks and against the Russians, with various success. Casimir was attacked by Charles Gustavus, king of Sweden, who overran n great part of Poland, and defeated the Poles in a great battle near Warsaw. By the peace of Oliva in 1660 Poland gave up Livonia to the Swedes, and Smolensk and Kim to the Russians. Casimir, seeing his subjects dissatisfied, abdicated the crown in 1667. He retired to France, where Louis XIV. gave him tho abbacy of St. Germain des Pr6s, and other benefices. He died at Nevem in 1672. Casimir V. was the last representative of the house of Jagello.