John II (king of Hungary and prince of Transylvania)
John II (John Sigismund Zapolya), 1540–71, king of Hungary and prince of Transylvania, son of John I. Through his mother, Isabel (daughter of Sigismund I of Poland), he was related to the Jagiello dynasty. As an infant, he was crowned king of Hungary on his father's death (1540). Sultan Sulayman I, on the pretext of protecting John's interests, invaded (1541) Hungary and took the capital, Buda, which remained in Ottoman hands for 150 years. John and Isabel received the principality of Transylvania under Ottoman suzerainty, but actual power was held by John's guardian, the monk George Martinuzzi, who sought to restore a unified Hungary. In 1551, Martinuzzi procured the deposition of John and Isabel and reunited Transylvania with Hungary, recognizing Ferdinand of Austria and Bohemia (later Holy Roman Emperor Ferdinand I) as king. Martinuzzi, made prince-primate and a cardinal, soon fell out with Ferdinand, who had him assassinated. On the pressure of Sulayman I the diet of Transylvania recalled (1556) John and Isabel, and when Ferdinand made peace (1562) with Sulayman, he also recognized John as ruler of Transylvania. Thus Hungary remained split into three states—an Austrian part, a Ottoman part, and Transylvania. It was under John II that the Transylvanian diet adopted (1564) Calvinism as the state religion. John was succeeded as prince of Transylvania by Stephen Báthory (see under Báthory, family).