The Vatican in Vatican City, Rome

Modernity brought many challenges to the Roman Catholic Church: Protestantism, the rise of modern science, the Enlightenment, nationalism, and dissent within the Catholic church itself. To address such issues Pope Pius IX called an ecumenical council--the first to be held since the Council of Trent (1545-1563). The Vatican Council of 1869-1870 approved the doctrine of papal infallibility, meaning that the church is preserved from error when the pope makes official pronouncements in matters of doctrine. This council is remembered as a reaction against modernity. Almost a century later, the Second Vatican Council would pursue a very different strategy.