This council was summoned by Pope Pius IX June 29, 1868. The first session was held in St Peter’s basilica on December 8, 1869, in the presence and under the direction of the pope.
The purpose of the council, besides the condemnation of contemporary errors, such as, the rising influence of rationalism, liberalism, and materialism, which the Church condemned, was to define the Catholic doctrine concerning the church of Christ.
There was discussion and approval of only two constitutions: “Dogmatic Constitution on the Catholic Faith” and “First Dogmatic Constitution on the Church of Christ,” the latter dealing with the primacy and infallibility of the bishop of Rome.
The doctrine of papal infallibility was not new and had been used by Pope Pius in defining as dogma, in 1854, the Immaculate Conception of Mary.
The discussion and approval of this latter constitution during the council gave rise, particularly in Germany, to serious controversies which led to the withdrawal from the Church of those known as “Old Catholics.”
The outbreak of the Franco-Prussian war led to the interruption and indefinite suspension of the council. It was in fact never resumed, nor was it ever officially closed. (8:23)