Pope Pius IX was the longest-reigning pope ever—he led the Church for 32 years from 1846 to 1878.

He is famous for two important teachings promulgated during his papacy: papal infallibility and the Immaculate Conception of Mary. He convened the first Vatican Council in 1869.

Pope Pius IX was the last pope to rule as sovereign over the Papal States, which had fallen to Italian nationalist forces by 1870.

Blessed Pope Pius IX was beatified in 2000 alongside Pope John XXIII, and is depicted in this stained glass window in the Basilia that shows the declaration of the dogma of the Immaculate Conception in 1854. He died on this date in 1878.

Blessed Pope Pius IX, who defined papal infallibility and Mary’s Immaculate Conception, pray for us!