June 7 - 1929 - The Ratification of the Lateran Treaty
From 1870, when Italian unification was completed with the capture of Rome, one of the thorniest political issues in Italy and all of Europe was the "Roman question." Essentially, the Pope, who had ruled the Papal States with temporal authority over actual territory, refused to acknowledge being under the control of the Italian government. Pope Pius IX in 1870 even declared himself a "Prisoner in the Vatican," a claim held up by all of his successors until 1929. The situation was only resolved by the Lateran Treaty, a negotiation between the Holy See and the Italian Fascist government of Benito Mussolini. Essentially, it said that Vatican City would be recognized as a sovereign nation, separate from Italy, while also allowing for some payments from Italy. This situation gave cover for Mussolini's pronouncements on Catholicism. The Papacy, meanwhile, could continue the practice of sending ambassadors to most nations and retaining its own authority. The Lateran Treaty was such a success it has been held up by Italy's government even after the establishment of democracy in 1947.