PIUS IX (Giovanni Maria Mastai-Ferretti, 1792–1878), pope of the Roman Catholic Church (1846–1878). Born on May 13 into a family belonging to the gentry of the Papal States, the future pope had his priestly formation delayed by an epilepsy-like illness. This left him with an excessively impulsive temperament for the rest of his life.

Mastai was ordained at Rome on April 10, 1815, and in an age when most young priests aimed at a successful career in the church, he stood out because of his piety and complete detachment from ecclesiastical honors. Serving as an assistant to the papal delegate to Chile (1823–1825) gave him an opportunity to see not only the difficulties that liberal governments with regalist tendencies could cause the church but also the new dimensions that missionary problems were acquiring. As bishop of Spoleto (1827), then of Imola (1832), in a region largely won over to the liberal and nationalist ideals...