Holy See
Although the Holy See is sometimes metonymically referred to as the "Vatican", the Vatican City State was distinctively established with the Lateran Treaty (1929) between the Holy See and Italy to ensure the temporal, diplomatic, and spiritual independence of the Papacy. As such, ambassadors are officially accredited to the Holy See and not the Vatican City State. Conversely, Papal nuncios to states and international organisations are recognised as representing the Holy See and the integrity of the Catholic Church along with its 1.3 billion members, not the Vatican City State, as prescribed also in the Canon law of the Catholic Church (1983). The "Holy See" thus refers to the See of Rome viewed as the central government of the Catholic Church. The Catholic Church, in turn, is the largest non-government provider of education and health care in the world, while the diplomatic status of the Holy See facilitates the access of its vast international network of charities.
Vatican during the Savoyard era (1870–1929)
Rome was declared Capital of Italy in March 1861, when the first Italian Parliament met in the kingdom's old capital Turin in Piemonte. However, the Italian Government could not take possession of its capital because Napoleon III kept a French garrison in Rome protecting Pope Pius IX. The opportunity to eliminate the last vestige of the Papal States came when the Franco-Prussian War began in July 1870. Emperor Napoleon III had to recall his garrison from Rome for France's own defence and could no longer protect the pope. Following the collapse of the Second French Empire at the battle of Sedan, widespread public demonstrations demanded that the Italian Government take Rome. King Victor Emmanuel II sent Count Gustavo Ponza di San Martino to Pius IX with a personal letter offering a face-saving proposal that would have allowed the peaceful entry of the Italian Army into Rome, under the guise of offering protection to the pope.