The First Vatican Council was a Catholic ecumenical council summoned by Pope Pius IX in 1868 and held from December 1869 to September 1870. It was the first ecumenical council held for over 300 years since the Council of Trent in 1545-63. Almost 750 churchmen from all parts of the Catholic world participated in the sessions.
The Council was summoned especially to consider the response of the Church to the emerging ideas of liberalism and materialism, both of which it condemned. Other questions were also considered, such the Catholic beliefs on the divine inspiration of Scripture, which were defined more closely. However, the most significant and far-reaching decision made by the Council was the formal definition of the dogma of Papal Infallibility, a question which was and remained controversial and led to bitter divisions within parts of the Church.
The Council was interrupted when military forces from the recently united Kingdom of Italy occupied Rome after the fall of the French Second Empire, which had until that time acted as protectors of the Papal States.
The First Vatican Council never achieved the importance of the previous Council of Trent or the following Second Vatican Council, both of which significantly reformed the Catholic Church. Nevertheless, the First Vatican Council was instrumental in reestablishing the credibility of the Papacy as well as a sense of Catholic unity and identity, all of which had suffered from the upheavals of the Napoleonic Era and the recent Unification of Italy.
- Hennesey, James. The First Council of the Vatican: The American Experience (1963) online edition
- Kirch, Joseph. "Vatican Council." in The Catholic Encyclopedia. Vol. 15. (1912) online