December 8, 1869: Pope Pius IX opens the First Ecumenical Council of the Vatican July 18, 1870 – The Dogmatic Constitution of the Church of Christ from the fourth session of Vatican I, "Pastor Aeternus", issues the dogma of papal infallibility among other issues before the fall of Rome in the Franco-Prussian War causes it to end prematurely and brings an end to the Papal States. Controversy over several issues leads to the formation of the Old Catholic Church. This council was not formally closed until 1960 by Pope John XXIII in preparation for the Second Vatican Council.