Pope Pius IX had the longest papacy in history, overseeing major events like the First Vatican Council, the declaration of the dogma of the Immaculate Conception, and the loss of the Papal States. His papacy is also noted for its response to liberalism and nationalism. Birth name: Giovanni Maria Battista Pietro Pellegrino Isidoro Mastai-Ferretti Nationality: Papal States, Kingdom of Italy Born: May 13, 1792 Died: February 7, 1878 Pontificate: June 16, 1846 – February 7, 1878