Ferdinand I (1503-1564) was Holy Roman emperor from 1555 to 1564. Before his accession and during his reign he pursued conciliatory policies toward the Protestants and the powerful German princes.
Born at Alcalá de Henares, Spain, on March 10, 1503, Ferdinand was the second son of Philip the Fair, Duke of Burgundy, and Joanna the Mad of Aragon and Castile. He lived for a long time in the shadow of his older brother, Charles, who was heir to the Hapsburg holdings in Germany and the Netherlands as well as to Spain and its Italian and South American possessions. In 1517 Charles went to Spain to take over the government, and the brothers met for the first time. Ferdinand was sent to the Netherlands to complete his education; there contact with Erasmian ideas had a lasting effect upon his attitude toward the Reformation.
On the death of their grandfather Emperor Maximilian I in 1519, Ferdinand's brother became Emperor Charles V, but Ferdinand received only the Hapsburg possessions of Upper and Lower Austria, Carinthia, Carniola, and, until 1534, Württemburg. In 1526, on the death of his brother-in-law Louis, Ferdinand became king of Bohemia and Hungary. His political position became rather ambiguous, for he had to combine the roles of German representative of imperial policy, German territorial prince, and independent king of Hungary, constantly harassed by the Turks. The necessity of finding support against the Turkish threat dictated much of his conciliatory attitude toward the Protestants.
The dangerous opposition of the Lutheran princes forced Charles V to secure Ferdinand's support. In 1531 Charles had Ferdinand elected king of the Romans, that is, designated successor to the imperial dignity. Later (1548-1551) Charles tried to dissuade Ferdinand from the imperial succession in order to preserve the empire for his own son Philip II. In 1551 a compromise was reached securing Philip's succession after Ferdinand's death. The agreement was not executed, however, and the imperial office remained in the hands of Ferdinand's direct descendants.
In German politics, which were closely connected to the religious issue, Ferdinand acted as a mediator between his brother and the Protestant princes. Although he remained a Catholic, Ferdinand supported efforts to reunite the confessions and to refer the disputed points to a general council. After Charles suffered a humiliating defeat by the Protestant princes in 1552, Ferdinand arranged the Treaty of Passau (1552), the first step toward the granting of religious freedom for the Lutheran princes (Treaty of Augsburg, 1555). Charles, however, refused to accept the decisions of the Augsburg Diet and abdicated. As emperor, Ferdinand continued his efforts toward reunion of the confessions with important concessions to the Protestants. He died in Vienna on July 25, 1564.
The life of Ferdinand I is recounted in Johannes Janssen, History of the German People at the Close of the Middle Ages (8 vols., 1883-1894; trans., 16 vols., 1896-1925). For additional information see Karl Brandi, The Emperor Charles V (1937; trans. 1939), and Friedrich Heer, The Holy Roman Empire (1967; trans. 1968).