Pío Nono is a significant figure in the history of the Catholic Church, serving as Pope from 1846 to 1878. His papacy is noted for its opposition to modernity and the rise of secularism, as well as for the declaration of the dogma of papal infallibility during the First Vatican Council in 1869-1870. Pío Nono also faced political challenges, including the loss of the Papal States, which were annexed by the newly unified Kingdom of Italy. His later years were marked by the establishment of the Vatican City as an independent state, solidifying the Pope's spiritual authority.