The author describes and analyzes the formation of the State of the Holy See, and the territorial delimitation of it, since Italian occupation of Rome in September 20, 1870. The article further addresses the diplomatic stages by which the prediction of the recognition of the Pope Leonine City was gradually to change to the wording of the Italian proposal, approved by the Italian Parliament May 13, 1871, which goes by the name of Guarantee-Act. The Author underlines the benefits that come to the Kingdom of Italy in the vote on the law, and the benefits that are also the Holy See, even if it rejects for now and until 1929.
Keywords: Stato temporale, Santa Sede, Regno d’Italia, Legge delle Guarantigie, iter diplomatico