Pope Pius IX

Reign: 1846 – 1878
Life: 1792–1878

His reign of nearly 32 years is the longest verified of any pope in history and second only to Saint Peter according to Catholic tradition. At the same time, France started the Franco-Prussian War and removed the troops that protected the Papal States, which allowed the Capture of Rome by the Kingdom of Italy on 20 September 1870. Thereafter, he refused to leave Vatican City, declaring himself a "prisoner in the Vatican". At the time of his election, he was a liberal reformer, and during his early papacy, he notably eased restrictions on Jewish movement and granted an amnesty to revolutionaries, but his approach changed radically after the Revolutions of 1848.

During Pope Pius IX's reign, Franz Joseph I of Austria ruled Austria, William III of the Netherlands ruled Netherlands, and Alexander II of Russia ruled Russia.