A prisoner in the Vatican is what Pope Pius IX called himself in 1870 when papal rule in Rome was ended by force, what was left of the Papal States was overthrown and their territory incorporated into the fairly recently united Kingdom of Italy under King Victor Emmanuel II. Early in the following year, 1871, the Italian capital was moved from Florence to Rome.
Centuries earlier, Popes in their secular role had gradually extended their control over neighbouring regions and through the Papal States ruled a large portion of the Italian peninsula for more than a thousand years until the mid 19th century, when the territory was seized by the Kingdom of Italy.
For the next 59 years, the Popes refused to accept their loss of the Papal States and secular power. In an act of defiance, they refused to leave the Vatican, describing themselves melodramatically as the 'prisoner in the Vatican'. Disputes between a series of "prisoner" popes and Italy were resolved on February 11, 1929 by three Lateran treaties, which established the independent state of the Vatican City.
Further reading
- Prisoner of the Vatican: The Pope's Secret Plot to Capture Rome from the New Italian State, by David I. Kertzer, Houghton Mifflin, 2004.