History's longest verified papacy defined infallibility then lost Rome
Pius IX—Giovanni Mastai-Ferretti—led the Catholic Church from 16 June 1846 to 7 February 1878, nearly thirty-two years, the longest verified reign after Peter's traditional claim. He called Vatican I in 1868, defined papal infallibility in 1870, and saw the council suspended as Italian troops ended the Papal States.
Early liberalism eased Jewish movement limits and amnestied revolutionaries, then flipped after 1848 when premier Pellegrino Rossi was assassinated and the pope briefly imprisoned in the Quirinal. The 1854 Immaculate Conception dogma and 1864 Syllabus of Errors condemned liberalism, modernism, and church–state separation. Peter's Pence fundraising and Curial centralization tightened global control.
John Paul II beatified him in 2000. The trajectory—from reforming hope to fortress doctrine while temporal power vanished—makes his reign a hinge between papal monarchy and modern spiritual sovereignty.
Infallibility arrived just as the papal army could no longer hold Rome: a theological climax timed to a geopolitical ending.
Giovanni Maria Mastai-Ferretti, ninth child of a noble family, was born in Senigallia on 13 May 1792. He joined the Papal Noble Guard in 1815 but was dismissed after an epileptic seizure, and when he was ordained on 10 April 1819 the pope at first required another priest to assist at his Masses until the attacks grew rarer. He travelled on the first papal mission to newly independent Chile, and Leo XII made him Archbishop of Spoleto at 35 in 1827, where he won a general pardon after the failed 1831 uprising. The 1846 conclave split between conservatives backing Lambruschini and liberals; he took only 15 votes on the first ballot before deadlocked moderates swung behind him. For about twenty months afterwards he was the most popular man in Italy, and English Protestants hailed him as a friend of light.
Source: Pope Pius IX
