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...