Bogdan Chmielnicki, chief of the revolted Cossacks, under the reigns of Ladislas IV. and John Casimir of Poland, born in 1593, died Aug. 25,1657. He was the son of a Polish nobleman, who settled among the Cossacks of the Ukraine. This people, who had long defended the eastern boundaries of Poland against the Tartars and Russians, were at that time subjected to grievous oppression. Their religion was persecuted, their freedom circumscribed; the castle of Kudak, called the curb of the Cossacks, was built to restrain them. Thus exasperated, they seized Kudak and massacred the garrison, but were soon subdued. After their defeat, Bogdan was sent to the court of Ladislas, where he was favorably received and appointed secretary of the Zaporogian Cossacks. But envy, suspicion, and hatred soon drove him forth, and finally made him a scourge of Poland. The intrigues of Czaplicki, an official at Czehryn, deprived him of an inherited estate, and of his wife, who deserted him and her religion, and caused his son Timofey to be publicly whipped. Having in vain sought for redress at Warsaw, he entered into a conspiracy with the Cossacks against the Poles, and sought the alliance of the khan of the Tartars, who ordered 80,000 of his people to assist him.

He now revolted, and commanded the massacre of all the Poles, Catholic priests, and Jews. The son of the hetman Potocki, who was sent against him, was deserted and fell in the battle at the Yellow Waters, and the hetman himself was made prisoner in that of Korsun (1648). Three other commanders were ignominiously defeated at Pilawce. Chmielnicki was master of the Ukraine, and carried terror, devastation, and death as far as Lemberg and Zamosc, but stopped there, awaiting the result of the election of a king, held at Warsaw. Under the new king, John Casimir, the war was continued with equal cruelty on both sides. Victories and defeats followed by turns, conditions of peace were offered and rejected, treaties concluded and violated, provinces desolated, fiendish atrocities committed; the serfs even of the Polish districts rose for freedom and rapine. Chmielnicki put himself under the protection of Turkey, of Russia (1654), and again under that of Poland (1656). A long war between Russia and Poland broke out after his death, which ended in 1667 with the cession of Kiev, Smolensk, and the Ukraine to the czar.