Ivan Mazepa, in full Ivan Stepanovych Mazepa, Mazepa also spelled Mazeppa (born about 1639, Mazepyntsi, near Bila Tserkva, Pol. [now Ukraine]—died Sept. 8 [Aug. 28, Old Style], 1709, Bendery, Moldavia [now Moldova]), hetman (leader) of Cossack-controlled Ukraine who turned against the Russians and joined the Swedes during the Second Northern War (1700–21).
Having served as a page at the court of the Polish king John Casimir, Mazepa was educated in western Europe but returned to his native land and in 1663 entered the service of Petro Doroshenko, the Cossack hetman of Right Bank (western) Ukraine.
During the 1660s and 1670s Mazepa’s transfer of loyalty between rival hetmans contributed to the complex and prolonged warfare (that continued into the 1680s) among the Turks, Russians, Poles, and various Cossack factions for control of the Ukraine.
Mazepa subsequently succeeded the established hetman of the Ukraine (1687) and fought against the Crimean Tatars (1689). When Peter I the Great took power, Mazepa managed to win Peter’s favour and retain his position in the Ukraine.
Peter, however, alienated Mazepa and the Cossacks, ordering them to perform uncustomary duties and allowing the Russian army to mistreat the Ukraine’s civilian population. Consequently, when the Second Northern War began (1700), Mazepa entered into secret negotiations with Charles XII of Sweden. When Charles led his forces into the Ukraine seeking supplies and reinforcements, Mazepa and 5,000 of his Cossacks joined the Swedes instead of going to the aid of the Russians (October 1708). Mazepa, however, was able neither to inspire the Ukrainian population to revolt against the Russians nor to supply the Swedes with enough Cossacks to prevent the Russians from inflicting a major defeat upon them at Poltava (June 1709). After that battle, Mazepa escaped with Charles into Turkish-controlled Moldavia, where he died.