Pius V (1504-1572) was pope from 1566 to 1572. An austere man, he put the decrees of the Council of Trent into effect and thus occupies a central position in the Catholic Reformation.

Antonio Ghislieri, who became Pius V, was born on Jan. 17, 1504, at Bosco Marengo near Alessandria in northern Italy. He was from a poor family. At 14 years of age Ghislieri entered the Order of Preachers and took the name Michele. He received his higher education as a friar at Bologna. In 1528 he was ordained at Genoa.

For more than 20 years Ghislieri gained a wide breadth of experience as professor of theology, superior in his order, and member of the Inquisition in Pavia, Como, and Bergamo. His dedication to the work of the Inquisition brought him to the attention of officials in Rome, including Giampietro Carafa, the future Pope Paul IV. In 1551 Pope Julius III appointed Ghislieri commissary general...