Ferdinand I (Spanish: Fernando I) was Holy Roman Emperor from 1558, king of Bohemia and Hungary from 1526, and king of Croatia from 1527 until his death. Before his accession, he ruled the Austrian hereditary lands of the Habsburgs in the name of his elder brother, Charles V, Holy Roman Emperor. Also, he often served as Charles' representative in Germany and developed useful relationships with German princes.
The key events during his reign were the contest with the Ottoman Empire, whose great advance into Central Europe began in the 1520s, and the Protestant Reformation, which resulted in several wars of religion. Ferdinand was able to defend his realm and make it somewhat more cohesive, but he could not conquer the major part of Hungary. His flexible approach to Imperial problems, mainly religious, finally brought more result than the more confrontational attitude of his brother.
Ferdinand's motto was Fiat iustitia, et pereat mundus: "Let justice be done, though the world perish".
His royal style was:
After ascending the Imperial Throne Ferdinand's full titulature, rarely used, went as follows: Ferdinand, by the grace of God elected Holy Roman Emperor, forever August, King in Germany, of Hungary, Bohemia, Dalmatia, Croatia, Slavonia, Rama, Serbia, Galicia, Lodomeria, Cumania and Bulgaria, etc. Prince-Infante in Spain, Archduke of Austria, Duke of Burgundy, Brabant, Styria, Carinthia, Carniola, Margrave of Moravia, Duke of Luxemburg, the Upper and Lower Silesia, Württemberg and Teck, Prince of Swabia, Princely Count of Habsburg, Tyrol, Ferrette, Kyburg, Gorizia, Landgrave of Alsace, Margrave of the Holy Roman Empire, Enns, Burgau, the Upper and Lower Lusatia, Lord of the Wendish March, Pordenone and Salins, etc. etc.