PIUS V. (Michele Ghislieri), pope from 1566 to 1572, was born at Bosco in the duchy of Milan, January 17, 1504. At the age of fourteen he entered the Dominican order, passing from the monastery of Voghera to that of Vigevano, and thence to Bologna. Having been ordained priest at Genoa in 1528, he settled at Pa via, where he lectured for sixteen years. He soon gave evidence of the opinions which found a more practical expression in his pontificate, by advancing at Parma thirty propositions in support of the papal chair and against the heresies of the time. As president of more than one Dominican monast-ery he proved himself a rigid disciplinarian, and, in accordance with his own wish to discharge the office of inquisitor, received an appointment to that post at Como. His zeal provoking resentment, he was compelled in 1550 to return to Rome, where, after having been employed in several inquisitorial missions, he was elected to the com-missariat of the Holy Office. Paul IV., who while still Cardinal Caraffa had shown him special favour, conferred upon him the bishopric of Sutri and Nepi, the cardinalate with the title of Alessandrino, and the honour—unique in one not of pontifical rank—of the supreme inquisitorship. Under Pius IV. he became bishop of Mondovi in Pied-mont, but his opposition to that pontiff procured his dismissal from the palace and the abridgment of his authority as inquisitor.

Before Ghislieri could return to his episcopate, Pius IV. died, and on January 7, 1566, he was elected to the papal chair with duly attendant prodigies, his coronation taking place on his birthday, ten days later. Fully alive to the necessity of restoring discipline and morality at Rome to ensure success without, he at once proceeded to reduce the cost of the papal court, compel residence, regulate inns, expel prostitutes, and assert the importance of ceremonial. In his wider policy, which was characterized throughout by a stringency which tended to defeat its own ends, the maintenance and increase of the efficacy of the Inquisition and the enforcement of the canons and decrees of the Tridentine council had precedence over all other considera-tions. The prudence of Commendone alone saved him at the commencement of his pontificate from trouble with Germany, as in the general diet of the empire at Augsburg (March 26, 1566) Pius saw a threatened invasion of his own supremacy and was desirous of limiting its discussions. In France, where his influence was stronger, he directed the dismissal of Cardinal Odet de Coligny and seven bishops, nullified the royal edict tolerating the extra-mural services of the Reformers, introduced the Roman catechism, restored papal discipline, and strenuously opposed all com-promise with the heretics—his exertions leading up in no small degree to the massacre of St Bartholomew. In the list of more important bulls issued by him the famous bull "In Ccena Domini" (1568) takes a leading place; but amongst others throwing light on his character and policy there may be mentioned his prohibition of qusestuary (February 1567 and January 1570); the condemnation of Michael Baius, the heretical professor of Louvain (1567); the reform of the breviary (July 1568); the denunciation of the dirum nefas (August 1568) ; the banishment of the Jews from the ecclesiastical dominions except Rome and Ancona (1569); the injunction of the use of the reformed missal (July 1570); the confirmation of the privileges of the Society of Crusaders for the protection of the Inquisi-tion (October 1570); the prohibition of discussions con-cerning the miraculous conception (November 1570); the suppression of the Fratres Humiliati for alleged profligacy (February 1571); the approbation of the new office of the Blessed Virgin (March 1571); the enforcement of the daily recitation of the canonical hours (September 1571) ; and the purchase of assistance against the Turks by offers of plenary pardon (March 1572). His antagonism to Elizabeth was shown, not only in the countenance lent by him to Mary Stuart and those who sought in her name to deliver England " ex turpissima muliebris libidinis servi-tute," but in the publication of a bull, dated April 27, 1570, excommunicating Elizabeth and releasing her sub-jects from their allegiance. His energy was in no respect more favourably exhibited than in his persistent and suc-cessful endeavours to form a general league against the Turks, as the result of which the battle of Lepanto (Oct. 7, 1571) was won by the combined fleet under Colonna. Three national synods were held during his pontificate— at Naples under Cardinal Alfonso Caraffa (whose family had, after inquiry, been reinstated by Pius V.), at Milan under Carlo Borromeo, and at Mechlin. His death took place on May 1, 1572, and he was canonized by Clement XI. on May 24th 1712. He was succeeded by Gregory XIII.