PIUS IV (Giovanni Angelo Medici), pope from 1559 to 1565, was born of humble parentage at Milan, March 31, 1499. His early career connects itself in some measure with the romantic rise of his elder brother from the position of bravo to that of Marchese di Marignano.
After studying at Bologna and acquiring reputation as a jurist, he went in 1527 to Rome, and as the favourite of Pope Paul III was rapidly promoted to the governorship of several towns, the archbishopric of Ragusa, the vice-legateship of Bologna, and in April 1549 to the cardinalate. On the death of Paul IV he was elected pope on December 28, 1559, and installed on the 6th January 1560. His first public acts of importance were to grant a general pardon to the participators in the riot which had closed the previous pontificate, and to bring to trial the nephews of his predecessor, of whom Cardinal Carlo Caraffa was strangled, and the duke Paliano, with his nearest connexions, beheaded.
On the 18th January 1562 the council of Trent, which had been suspended by Julius III, was opened for the third time. Great skill and caution were necessary to effect a settlement of the questions before it, inasmuch as the three principal nations taking part in it, though at issue with regard to their own special demands, were prepared to unite their forces against the demands of Rome. Pius, however, aided by Morone and Charles Borromeo, proved himself equal to the emergency, and by judicious management - and concession - brought the council to a termination satisfactory to the disputants and favourable to the pontifical authority. Its definitions and decrees were confirmed by a bull dated January 26, 1564; and, though they were received with certain limitations by France and Spain, the famous Creed of Pius IV., or Tridentine Creed, remained the authoritative expression of the Catholic faith. The more marked manifestations of stringency during his pontificate appear to have been prompted rather than spontaneous, his personal character inclining him to moderation and ease.
Thus a monitory, issued in 1564, summoning the queen of Navarre before the Inquisition on a charge of Calvinism, was withdrawn by him in deference to the indignant protest of Charles IX; and in the same year he published a bull granting the use of the cup to the laity of Austria and Bohemia. One of his strongest passions appears to have been that of building, which somewhat strained his resources in contributing to the adornment of, Rome, and in carrying on the work of restoration, erection, and fortification in various parts of the ecclesiastical states. A conspiracy against him, headed by the Catholic fanatic Benedetto Accolti, was discovered and crushed in 1565. He died shortly afterwards, on December 9th of that year, and was succeeded by Pius V.
text from the 9th edition (1888) of an unnamed encyclopedia