The First Vatican Council was summoned by Pope Pius IX on 29 June 1868. This council was summoned by Pope Pius IX by the bull Aeterni Patris of 29 June 1868. The first session was held in St Peter’s Basilica on 8 December 1869 in the presence and under the presidency of the Pope.

The purpose of the council was, besides the condemnation of contemporary errors, to define the Catholic doctrine concerning the Church of Christ.