Pope Leo XIII was head of the Catholic Church from 20 February 1878 until his death in July 1903. Living until the age of 93, he was the oldest pope, whose age can be validated, holding office and had the fourth-longest reign of any pope, behind those of St. Peter, Pius IX and John Paul II.

Pope Pius IX was head of the Catholic Church from 1846 to 1878. His reign of 32 years is the second longest of any pope in history, behind that of Saint Peter. He was notable for convoking the First Vatican Council in 1868 and for permanently losing control of the Papal States in 1870 to the Kingdom of Italy. Thereafter, he refused to leave Vatican City, declaring himself a "prisoner in the Vatican".