Pope Pius IV (224º): Council of Trent — Complete Guide
Pontificate: 26 December 1559–9 December 1565
Pius IV was the 224th pope of the Catholic Church, reigning 26 December 1559–9 December 1565 during the Renaissance papacy. Instituted the Tridentine Creed.
Who Was Pope Pius IV?
This biography of Pius IV (224º) covers background, major events, and legacy in the line of St. Peter. Common search topics include Council of Trent. During the Renaissance papacy, the Bishop of Rome exercised teaching, sanctifying, and governing authority for the universal Church.
Early Life & Background
Before election he was known as Giovanni Angelo Medici. Born 31 March 1499 Milan, Duchy of Milan, he entered a world shaped by politics and piety very different from today's global Church. Subject of the Duchy of Milan.
Historical Context
Pius IV sat on the Chair of Peter during the Renaissance, when popes were among the most powerful patrons of art and architecture in Europe — but also faced corruption scandals, the Protestant Reformation, and the discovery of the New World. Reopened and closed the Council of Trent(1563).
Pontificate & Key Events
The pontificate (26 December 1559–9 December 1565) centered on governance during the Renaissance papacy. Ordered public construction to improve the water supply of Rome.
Papal Acts & Achievements
Pius IV left a distinct mark through decisions that historians still debate and Catholics still study. His reign contributed to the continuous apostolic succession now numbering 267 popes.
Key Highlights
- 224th pope of the Catholic Church
- Pontificate: 26 December 1559–9 December 1565
- Reopened and closed the Council of Trent(1563).
- Shepherded the Church during the Renaissance papacy
- Successor of St. Peter in the official Catholic list
Legacy in the Catholic Church
Pius IV remains pope 224º in the Annuario Pontificio. Read against the Renaissance papacy, his pontificate shows how Providence works through imperfect ministers without abandoning the Barque of Peter.
Why Catholics Study This Pope Today
Studying Pius IV helps Catholics see how the Holy Spirit guided the Church through the Renaissance papacy — with human weakness and grace intertwined. Primary sources from this pontificate — bulls, conciliar acts, or encyclicals — reward readers who want depth beyond summaries. Place this pope in context using our chronological list of all 267 popes and the biographies of his immediate predecessor and successor linked below.
Place in the Line of Succession
Pius IV followed Pope Paul IV (223º) in the unbroken line of apostolic succession from St. Peter. Upon his death or resignation, he was succeeded by Pope St. Pius V (225º), who continued the mission of shepherding the universal Church. Explore the full chronological chain in our complete list of all 267 popes, or read the biographies of neighboring pontiffs linked below.