Pope St. Leo I the Great (45º): Attila, Chalcedon & Papal Authority
Pontificate: 29 September 440 –10 November 461
St. Leo I the Great was the 45th pope of the Catholic Church, reigning 29 September 440 –10 November 461 during the apostolic and patristic Church. Feast day 10 November. The Catholic Church venerates him as a saint.
Who Was Pope Leo I the Great?
This biography of St. Leo I the Great (45º) covers background, major events, and legacy in the line of St. Peter. Common search topics include the Great, Chalcedon. During the apostolic and patristic Church, the Bishop of Rome exercised teaching, sanctifying, and governing authority for the universal Church. Catholics honor him as a saint whose intercession remains available to the faithful.
Early Life & Background
Born Etruria, Italy, Roman Empire, he entered a world shaped by politics and piety very different from today's global Church.
Historical Context
Leo I the Great shepherded the Church when Christianity was still an outlawed or barely tolerated faith in the Roman Empire. Papal records from this era are scarce, but tradition and archaeology preserve the memory of these earliest successors of St. Peter. Wrote the Tome, which was instrumental in the Council of Chalcedon(451) and in defining the hypostatic union.
Pontificate & Key Events
The pontificate (29 September 440 –10 November 461) centered on governance during the apostolic and patristic Church. Feast day 10 November. Convinced Attila the Hun to turn back his invasion of Italy. Convinced the Vandals to spare the lives of the citizenry of Rome during their sack of the city.
Papal Acts & Achievements
Leo I the Great left a distinct mark through decisions that historians still debate and Catholics still study. Also revered as a saint in Eastern Christianity, with a feast day of 18 February.
Key Highlights
- 45th pope of the Catholic Church
- Pontificate: 29 September 440 –10 November 461
- Venerated as a saint in the Catholic Church
- Feast day 10 November.
- Wrote the Tome, which was instrumental in the Council of Chalcedon(451) and in defining the hypostatic union.
- Also revered as a saint in Eastern Christianity, with a feast day of 18 February.
Legacy in the Catholic Church
St. Leo I the Great remains pope 45º in the Annuario Pontificio. The Church venerates his feast and holds up his virtues for imitation. Read against the apostolic and patristic Church, his pontificate shows how Providence works through imperfect ministers without abandoning the Barque of Peter.
Why Catholics Study This Pope Today
Studying St. Leo I the Great helps Catholics see how the Holy Spirit guided the Church through the apostolic and patristic Church — with human weakness and grace intertwined. You may ask Leo I the Great for intercession and look up his feast in the Roman calendar or Martyrology. 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
St. Leo I the Great followed Pope St. Sixtus III (44º) in the unbroken line of apostolic succession from St. Peter. Upon his death or resignation, he was succeeded by Pope St. Hilarius (46º), 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.