Pius IX (pope)

Pius IX reigned longer than any pope, nearly thirty-two years, through the collapse of the papacy's worldly power. He lost the Papal States as Italy was unified, and in 1870 Rome itself fell, leaving him the self-styled prisoner in the Vatican. He defined the dogma of the Immaculate Conception in 1854, issued the Syllabus of Errors in 1864 condemning liberalism and modern ideas, and called the First Vatican Council, which declared the pope infallible when defining doctrine.