St. Leo the Great
He wrote the letter on Christ's two natures that the Council of Chalcedon accepted as the Church's faith, went north to meet Attila and talked him into leaving Italy, and walked out defenceless to meet Genseric's Vandals and ask them to spare Rome.
Died 461 · Canonized
No year of birth is recorded here, and the encyclopedia gives the reason in its own first words: "Place and date of birth unknown; died 10 November, 461". Nothing else held for him gives a birth year either, so no age at death is recorded. His death date is firm and both documents agree on it, and it is also the day the Church keeps him.
Nobody knows where or when Leo was born, and the encyclopedia says so in its opening words. He first appears as a deacon of the Church of Rome, trusted enough that the imperial court sent him to Gaul in 440 to settle a quarrel between its chief general and its chief magistrate. He was still there when the pope died and word came that he had been elected in his place.
He was consecrated on 29 September 440 and governed for twenty-one years. The empire in the West was coming apart, and a bishop of Rome found himself doing work nobody had given him: feeding a city filling with refugees, arguing with emperors, going out to meet armies.
What he is remembered for is a letter. A monk called Eutyches was teaching that Christ's humanity had been swallowed up in his divinity, and Leo wrote to the bishop of Constantinople that the two natures are united in one person, without confusion and without separation. When it was read aloud at the Council of Chalcedon in 451 the bishops called out that Peter had spoken through the mouth of Leo.
In 452 he went north with a Roman delegation, met Attila near Mantua, and Attila turned back. Three years later it went worse. Genseric's Vandals reached the gates and plundered Rome for two weeks. Leo could not stop them. He walked out to meet them anyway, unarmed and with his clergy around him, and what he got was a promise that the city would not be burned and that the great basilicas, full of people hiding, would be spared.
He is the first pope whose preaching survives: almost a hundred sermons and about a hundred and fifty letters. He died on 10 November 461, the day the Church still keeps him, and was buried beside St Peter.
What they carried
The empire was coming apart around him, and Rome filled with refugees and famine. He also lost: he could not stop Genseric's Vandals sacking the city for two weeks in 455. Benedict XVI does not smooth it over, calling the outcome "not as successful" and the attempt "a sign of courage that still amazes us".
State of life
pope · Doctor of the Church · theologian
Themes
preaching · writing · teaching · peacemaking · courage under pressure · speaking truth to power · care of the poor · reform
Benedict XVI on Saint Leo the Great (General Audience, 5 March 2008)
- There have been fourteen popes named Leo and this is the first of them. Benedict XVI makes the point himself, speaking in 2008: "He was the first Bishop of Rome to have been called Leo, a name used subsequently by another 12 Supreme Pontiffs". A candidate who has heard the name from the news has almost certainly heard it of a different man.
- That sentence of Benedict XVI's was true when he said it in 2008 and is not true now. Leo XIV was elected in 2025, so the first Leo has been followed by thirteen others rather than twelve. The quotation is kept as he spoke it, with its date, and is not repeated anywhere in this record as a present fact.
- The feast is 10 November, and it is an obligatory memorial. The Universal Calendar of the Bishops' Conference of England and Wales prints under 10 November "St Leo the Great, Pope, Doctor of the Church" with the word memorial beneath it. https://www.liturgyoffice.org.uk/Calendar/Universal/NovUC.shtml The United States calendars agree: "Saint Leo the Great, Pope and Doctor of the Church", in white, on 10 November. https://www.usccb.org/resources/2026cal.pdf THE ENCYCLOPEDIA GIVES A DIFFERENT DAY AND IT IS NOT THE ONE USED HERE. It says "In the Latin Church the feast day of the great pope is held on 11 April, and in the Eastern Church on 18 February". That is the pre-1969 Roman date. The current calendar keeps him on 10 November, which is also the day he died.
- Benedict XVI's catechesis exists in both English and Italian, and on one sentence they do not say the same thing. Of the Council of Chalcedon the Italian says it "fu la più importante assemblea fino ad allora celebrata nella storia della Chiesa" — the most important assembly celebrated in the history of the Church UP TO THAT TIME. The English drops the limit and says it "was the most important assembly ever to have been celebrated in the history of the Church". The bounded claim is the one this record follows, because Italian is the language the audience was given in.
- Where a papal catechesis exists in more than one language, this corpus reads the language it was delivered in and treats the others as translations of it. Both editions of the 5 March 2008 audience were fetched before anything was written from either.
- The two documents do not agree on who sent Leo to Gaul, and this record names neither. The encyclopedia says "Leo was sent to Gaul by Emperor Valentinian III to settle a dispute", and places it loosely in the pontificate of Sixtus III. Benedict XVI says it was "Galla Placidia, who then ruled the Empire of the West, to send him to Gaul", and dates it to 440. Galla Placidia was Valentinian's mother and had ruled as his regent, so the two accounts may be describing one court in two ways — but they name different people, and nothing held here settles which.
- Nothing is recorded here about his birth because the encyclopedia says plainly that nothing is known: its article opens "Place and date of birth unknown; died 10 November, 461". What it does pass on, and attributes rather than asserts, is the Liber Pontificalis's report that "Leo was a native of Tuscany and his father's name was Quintianus". Benedict XVI gives the Tuscan origin without a source — the Italian reads "Leone era originario della Tuscia" — and no birth year at all.
- The Vandal sack of Rome in 455 is in this record as something he failed to prevent, because that is how the pope who preached about him tells it. Benedict XVI: "the outcome of another Papal initiative three years later was not as successful", and Leo "did not manage to prevent" the Vandals entering the city, which they plundered for two weeks. He went out to them anyway — "defenceless and surrounded by his clergy, went forth to meet the invader to implore him to desist" — and calls the attempt "a sign of courage that still amazes us". What it achieved was that the city was not burned and the great basilicas, where people were sheltering, were spared.
- The letter is the centre of his record. Eutyches, a monk of Constantinople, had been excommunicated for teaching that Christ's humanity was absorbed into his divinity, and appealed to Rome. Leo replied to Flavian, the patriarch, with what the encyclopedia calls "his sublime dogmatic letter to Flavian" — known as the Tome — setting out the union of the two natures in one person, in Benedict XVI's words "without confusion and without separation". Read aloud at the Council of Chalcedon in 451, it drew from the bishops the acclamation the council's own acts preserve: "Peter has spoken through the mouth of Leo", or in the Italian, "Pietro ha parlato per bocca di Leone". The encyclopedia records that the council "solemnly accepted Leo's dogmatical epistle to Flavian as an expression of the Catholic Faith".
- Leo is the Latin for lion. The forms carried here are the ones a candidate is likely to arrive with — Leon, Leone, León, Léon, Lev — together with Leona and Léonie, which are the same name given to a girl. Leonard, Leonardo, Leandro and Lionel are NOT forms of it, whatever they look like: Leonard is Leonhard, and the encyclopedia carries two saints called Leonard with articles of their own.
- No patronage is recorded for him. All three documents held for him were searched for "patron", "patrono", "patrona" and "protettore" and the terms returned zero occurrences — in the encyclopedia article and in both the English and Italian editions of the catechesis. No held document declares one.
- This is the first pope in this list. Peter is here, but his record is built on the fisherman and the apostle rather than on the office, which is how the Gospels and the Acts present him.
- He was declared a Doctor of the Church in 1754, nearly thirteen centuries after his death. The encyclopedia: "In 1754 Benedict XIV exalted him to the dignity of Doctor of the Church". Benedict XVI opens his catechesis with the same fact, calling him "a Pope who in 1754 Benedict XIV proclaimed a Doctor of the Church". He is also, Benedict XVI says, "the first Pope whose preaching to the people who gathered round him during celebrations has come down to us" — almost a hundred sermons and about a hundred and fifty letters survive.
- Catholic Encyclopedia (Herbermann, 1907-1913), J.P. Kirsch, "Pope St. Leo I (the Great)", vol. 9, 1910 — the source for the unknown birth, the Tuscan origin and the father's name from the Liber Pontificalis, the diaconate under Celestine I, the mission to Gaul, the election and the consecration on 29 September 440, the Eutyches affair and the letter to Flavian, the Robber Synod and Chalcedon, the meeting with Attila at Mincio and the Vandal sack, the building and restoring of churches, the sermons, the doctorate of 1754 and the burial at St Peter's. https://www.newadvent.org/cathen/09154b.htm
- Benedict XVI, General Audience of 5 March 2008, "Saint Leo the Great", given in the Paul VI Hall — the source for the Tuscan origin and the diaconate about 430, for Galla Placidia and the mission to Gaul, for the meeting with Attila at Mantua and the reading of the sack of Rome that this record follows, for the acclamation at Chalcedon, for the sermons and letters, and for the charity in a city he describes as "tried by famines, an influx of refugees, injustice and poverty". https://www.vatican.va/content/benedict-xvi/en/audiences/2008/documents/hf_ben-xvi_aud_20080305.html