Pope Pius IX

Pope Pius IX, who reigned from 1846 to 1878, was one of the longest-serving popes in history. He is known for defining the dogma of the Immaculate Conception, which states that Mary was conceived without original sin. His papacy was marked by significant political and social turmoil, including the loss of the Papal States and the rise of modern nationalism. Pius IX also convened the First Vatican Council, which affirmed the doctrine of papal infallibility, stating that the pope cannot err when proclaiming doctrines on faith and morals. He became a polarizing figure, both revered and criticized.