The Kingdom of Hungary had been part of the Habsburg realms since 1526 when the Sultan Süleyman I the Magnificent (ruled 1520–1566) defeated the Hungarian armies at Mohács. The King of Hungary and Bohemia, Louis II (ruled 1516–1526), died in the battle. Due to the dynastic agreement between the Jagiellonians and the Habsburgs, the latter were to take over Hungary and the Czech lands should the former fail to produce male heirs. In the other case, the Jagiellonians could hope for the imperial throne in Vienna. Mean­while, the Ottoman Empire seized most of Hungary proper, including Buda (1541), the seat of Hungarian Kings. Foreseeing this outcome, the Habsburgs had already moved the capital of their part, known as Royal Hungary, to Preßburg (Bratislava)¹ in 1536. Between 1526 and 1570, the native Zápolya (Szapolyai) dynasty contested the Habsburg rule. The Zápolyas had held the governorship of Transylvania since 1511, and made this region into their stronghold. While the Habsburgs championed Catholicism according to the logic of the Counter-Reformation, Transylvania became a haven for Hungarian Protestants. In 1568, the Transylvanian Diet of Torda (Turda) decreed religious freedom for Catholics, Lutherans, Calvinists, and Unitarians. As serfs, the Romancephone Walachians, who professed Orthodox Christianity, were excluded from this arrangement. Such freedoms could be negotiated among and conferred only on the nobility — the Hungarian natio. These provisions of religious freedom were not extended to Jews and Muslims living in Transylvania, either. A segment of Transylvania's Orthodox population improved its legal status only when their hierarchy joined the Catholic fold at the end of the 18th century. This was an emulation of the Uniate Union of Ungwar (Ungvár in Magyar, and today Uzhhorod in Ukraine) in eastern Upper Hungary, which had been finalized in 1646.