FERDINAND I of Habsburg, EMPEROR. — Son of the Archduke of Austria Philip the Handsome and Joanna the Mad, born in Alcalá (New Castile) on 10 March 1503, died in Vienna on 25 July 1564. In 1521 he received from his brother Charles V the Austrian hereditary lands and succeeded in suppressing the peasant revolt in Tyrol, Austria, and Styria. In the same year he married Anna, sister of Louis II, King of Bohemia and Hungary. Upon the death of his brother-in-law at Mohács (1526), he claimed succession to both kingdoms: he was recognized in Bohemia but not in Hungary, where the majority elected as king the voivode of Transylvania, John Szapolyai, supported by Suleiman II, who then besieged Vienna itself (1529). The Turkish peril and the Lutheran schism were the fundamental problems of Ferdinand’s reign.
He presided over various diets in Germany, where he sought to reconcile Catholics and Protestants. In 1531 he was elected King of the Romans. In 1552 he concluded with the Protestants the Treaty of Passau, and three years later the Religious Peace of Augsburg, in which, among other things, he attempted through the “reservatum” to safeguard the principal ecclesiastics. After the abdication of Charles V, on 14 March 1558 he was named emperor. When the Council of Trent was reconvened in 1562 by Pius IV, Ferdinand, moved by the situation in Germany, presented his own plan of reform, which included, among other things, the suppression of clerical celibacy and for the laity communion under both kinds. Personally devoted to the Church, he was a tolerant, just, and peaceable prince, well-liked by his subjects despite religious differences.