First Vatican Council

First Vatican Council
Date	8 December 1869 – 20 September 1870 (de facto) 8 December 1869 – 5 June 1960 (de jure)
Accepted by	Catholic Church
Previous council	Council of Trent (1545–1563)
Next council	Second Vatican Council (1962–1965)
Convoked by	Pope Pius IX
President	Pope Pius IX
Attendance	744
Topics	Rationalism, liberalism, materialism; biblical inspiration; papal infallibility
Documents and statements	Two constitutions: Dei Filius Pastor aeternus
Chronological list of ecumenical councils

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Ecumenical councils of the Catholic Church
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4th–5th centuries
Nicaea I (325) Constantinople I (381) Ephesus (431) Chalcedon (451)
6th–9th centuries
Constantinople II (553) Constantinople III (680–681) Nicaea II (787) Constantinople IV (869–870)
12th–14th centuries
Lateran I (1123) Lateran II (1139) Lateran III (1179) Lateran IV (1215) Lyon I (1245) Lyon II (1274) Vienne (1311–12)
15th–16th centuries
Constance (1414–18) Basel–Ferrara–Florence (1431–42) Lateran V (1512–17) Trent (1545–63)
19th–20th centuries
Vatican I (1869–70) Vatican II (1962–65)
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The First Ecumenical Council of the Vatican, commonly known as the First Vatican Council or Vatican I, was the 20th ecumenical council of the Catholic Church, held three centuries after the preceding Council of Trent which was adjourned in 1563. The council was convoked by Pope Pius IX on 29 June 1868, under the rising threat of the Kingdom of Italy encroaching on the Papal States. It opened on 8 December 1869 and was adjourned on 20 September 1870 after the Italian Capture of Rome. Its best-known decision is its definition of papal infallibility.^[1][2]

The council's main purpose was to clarify Catholic doctrine in response to the rising influence of the modern philosophical trends of the 19th century. In the Dogmatic Constitution on the Catholic Faith (Dei Filius), the council condemned what it considered the errors of rationalism, anarchism, communism, socialism, liberalism, materialism, modernism, naturalism, pantheism, and secularism.^[3]

Its other concern was the doctrine of the primacy (supremacy) and infallibility of the Bishop of Rome (the Pope),^[4] which it defined in the First Dogmatic Constitution on the Church of Christ (Pastor aeternus).^[5]