Pope Stripped of all Power- Italy Unified

The unification of Italy, the Risorgimento, had over preceding decades brought most of the peninsula under the rule of the Kingdom of Italy, proclaimed in 1861 under King Victor Emmanuel II. Rome and its surrounding territory, however, remained under the temporal sovereignty of the Pope, protected by a French garrison that Napoleon III had stationed there to guard papal independence.

The outbreak of the Franco-Prussian War in 1870 forced France to withdraw its troops from Rome to meet the Prussian threat. With the city no longer shielded, Italian forces advanced and, after a brief bombardment, breached the walls at the Porta Pia on 20 September 1870. Rome was occupied, and a plebiscite soon confirmed its annexation to the Italian kingdom, completing the unification of the nation.

The seizure of Rome stripped Pope Pius IX of his remaining temporal power. Refusing to recognize the new order, the Pope withdrew into the Vatican and declared himself a prisoner, inaugurating the long estrangement between the papacy and the Italian state known as the Roman Question, which remained unresolved until the Lateran Treaty of 1929. Rome became the capital of a fully unified Italy.