In the Lateran Treaty, Italy and the Holy See recognised each other'ssovereignty, writes Jim Cantwell
Seventy-five years ago today, an American travel writer, Sydney A Clark, was being driven around Rome, a lone passenger on a tourist tram. He became bored with the perfunctory patter of his guide until, suddenly, the guide's "monotonous drone" ceased.
"Ecco, signore," the guide shouted excitedly, "it is the pope's flag. The treaty has been signed." Soon they saw hundreds of yellow and white flags being raised, together with many Italian flags.
The Lateran Treaty, signed by the Holy See and the Italian government of Benito Mussolini on February 11th 1929, established Vatican City as a sovereign state. In return, the Holy See recognised the Italian state, with Rome as its capital.
And so the Roman Question, the last great divisive issue in the history of the papal states, was "finally and irrevocably" settled.
The papal states had once covered vast areas of Italy, as well as Avignon in France. In his important study, The Lands of St Peter, Peter Partner reckons that the most important use to which the income from the pope's landed property was put was the provisioning of the city of Rome.
"The Bishop of Rome undertook responsibility, which his successors preserved until 1870, of feeding the Roman proletariat . . . The pope possessed something between an immense soup kitchen and a public ministry of supply."
Temporal power meant much more than that, of course. It made popes mighty monarchs, at least during those periods when they were not beholden to various emperors. All too often this power did nothing to enhance their spiritual authority. Priests governed millions of people, for the pope's vast system of civil administration was clerical from top to bottom.
The pope's temporal power lasted for over a millennium, but it could not withstand the fall-out from the French Revolution. Historian J M Roberts has remarked that the 19th-century papacy "sometimes seemed the most threatened of all religious institutions".
France took over its papal lands in 1791 and by 1861 all the pope's Italian territories had fallen to the forces of Garibaldi and Victor Emmanuel.
The one exception was Rome, which the pope could hold only with the help of French troops. When these were withdrawn in 1870, Italian troops marched in and parliament proclaimed the city Italy's capital.
In protest, Pius IX made himself a prisoner of the Vatican. He refused to recognise the Italian state, holding firmly to the belief that he was merely the guardian of church lands and could not hand them over.
Italy enacted the so-called Law of Guarantees in May 1871, granting the Vatican extra-territorial status, roughly equivalent to that of embassies under international law. While Pius IX immediately repudiated the law, which was in any case a unilateral measure, it was to provide the basis for an eventual solution.
Pius IX's successor, Leo XIII, described the independence granted by the Law of Guarantees as "only apparent and transitory, for it is subject to the will of others. Those who conferred it yesterday can cancel it tomorrow". For the pope to be able to exercise his office freely and independently, he asserted, it was essential that the Holy See have full sovereignty over a piece of land, however tiny.
Deep animosity between fellow-Sicilians, the Italian Prime Minister, Francesco Crispi, and Leo's secretary of state, Cardinal Mariano Rampolla, made relations worse for a time. However, Leo himself resisted pressure from Rampolla to up the ante. This made it possible for his successor, Pius X, to initiate a process of conciliation.
The next pope, Benedict XV, was elected only a month after the First World War broke out and could do little until hostilities ceased. But in 1919 he gave his secretary of state, Cardinal Pietro Gasparri, authority to move decisively by formally proposing independence for the Vatican. Only the fall of the Italian government prevented a settlement at that time.
There were helpful symbolic gestures from both sides. On Benedict's death, in 1922, Italy declared a period of state mourning, in marked contrast to the funeral of Pius IX, when Italian troops stood by as an angry mob almost succeeded in pitching his corpse into the Tiber.
The new pope, Pius XI, blessed the city from the main balcony of St Peter's Basilica, which none of his predecessors had done for many years. The ice was decisively broken.
In the Lateran Treaty, signed seven years later, Italy and the Holy See recognised each other's sovereignty and abrogated the Law of Guarantees. The treaty was reaffirmed, with minor amendments, in a new concordat in 1984.
Historian Owen Chadwick has said that a "big part of the rise in the pope's authority as a churchman was connected with the collapse of his authority as a politician". Still, he remains an elected monarch, though now a minor one, at least in civilian terms. Vatican City in west Rome is the world's smallest sovereign state. Its total area of 108 acres would fit into Phoenix Park 16 times over.
The secretary of state, currently Cardinal Angelo Sodano, is the pope's prime minister. The state has a permanent population of 830 and a staff of 3,000, who live outside the Vatican. Thirteen buildings in Rome and the pope's summer home at Castel Gandolfo enjoy extra-territorial rights.
The Holy See has diplomatic relations with more than 120 countries and is still considered an important listening post. It is a member of 11 international bodies and has observer status at the United Nations.
Pope John Paul II, spiritual leader of the world's 1.1 billion Catholics, justified the Vatican's sovereignty during his first visit to the UN 25 years ago by stressing the "need of the papacy to exercise its mission in full freedom, and to be able to deal with any interlocutor, whether a government or an international organisation, without dependence on other sovereignties".
Jim Cantwell is the author of The Election of the Pope (St Paul's)