Ital. Lo Stato della Chiesa, from 754 to 1870 an independent territory under the temporal rule of the popes, also called the States of the Church and the Pontifical States. The territory varied in size at different times; in 1859 it included c.16,000 sq mi (41,440 sq km) extending north-south on the Italian peninsula, from the Adriatic Sea and lower course of the Po River to the Tyrrhenian Sea, thus including the present regions of Latium, Umbria, Marche, and eastern Emilia-Romagna.
The nucleus of the states consisted of endowments given to the popes from the 4th cent. in and around Rome, in other areas of the Italian mainland, and in Sicily, Sardinia, and other lands; these came to be called the Patrimony of St. Peter. The popes gradually lost their more distant lands, but in the duchy of Rome papal power became stronger and increasingly independent of the Eastern emperors and of the other states in Italy.
In 754 (confirmed 756), Pepin the Short gave to Pope Stephen II the exarchate of Ravenna and the Pentapolis (Rimini, Ancona, Fano, Pesaro, and Senigallia). (Like Pope Zacharias, Pope Stephen II had recognized Pepin as rightful king of the Franks, and Pepin now needed papal assistance against the Lombards.) Over these vast territories the popes were long unable to exercise effective temporal sovereignty. In 774, Charlemagne confirmed the donation of his father, Pepin the Short; moreover, to give the papal claim to temporal power greater antiquity, the so-called Donation of Constantine (see Constantine, Donation of) to Pope Sylvester I was forged. On its basis later popes also claimed suzerainty over Naples, Sicily, and Sardinia. In 1115, Countess Matilda of Tuscany, by leaving her territories to the church, helped to precipitate a long struggle between popes and emperors.
In Rome itself, the popes' temporal power, almost nonexistent in the 10th cent., remained greatly limited until the 14th cent. by the interference of the emperors, by the power of the nobles, and by the ambitions of the commune of Rome, which contended that its authority also extended over the Papal States. In the 13th and 14th cent., the emperors renounced their claims to the duchy of Spoleto, the Romagna, and the March of Ancona; however, the free communes and petty tyrannies that dominated these regions long resisted effective papal control. The Comtat Venaissin, a papal possession in S France until 1791 (though not a part of the Papal States), was acquired in 1274; in 1309, Avignon became the seat of the popes. From 1309 to 1417, during the “Babylonian Captivity” at Avignon and the Great Schism, the Papal States were in chaotic condition, only temporarily relieved by the efforts of Cardinal Albornoz.
Actual control by the papacy of its territories began in the 16th cent., when Cesare Borgia, son of Pope Alexander VI, conquered the petty states of the Romagna and Marche; after his fall (1503) most of them passed directly under papal rule. In the early 16th cent., Pope Julius II consolidated papal power by abolishing local autonomies and by participating effectively in the Italian Wars. The last principalities to lose their autonomy to the popes were Ferrara (1598) and Urbino (1631). The duchy of Castro was added in 1649. Parma and Piacenza were alienated (1545) through the nepotism of Pope Paul III.
After the Counter Reformation (16th cent.) the spiritual power of the papacy grew while its political power waned. Papal troops, mostly Swiss and other mercenaries, offered almost no resistance to the French invaders under Napoleon Bonaparte (see Napoleon I) in 1796. Pius VI and his successor, Pius VII, saw their states curtailed, occupied, and twice abolished between 1796 and 1814. The Congress of Vienna fully restored (1815) the states of the papacy and placed them under Austrian protection.
Conspiracies and revolutions (notably of 1831 and 1848–49) characterized the following decades. Pius IX was liberal at his accession and granted his states a constitution, but the events of 1848 turned him against the revolutionists. During the Risorgimento, only French intervention at Rome prevented the total absorption of the Papal States. After the Austrians left (1859) Bologna and the Romagna, both united (1860) with the kingdom of Sardinia, as did Marche and Umbria. Giuseppe Garibaldi invaded the remaining Papal States twice but was prevented from taking Rome—in 1862 by the intervention of Victor Emmanuel II of Italy, and in 1867 by Napoleon III.
The fall of Napoleon permitted Victor Emmanuel to seize Rome in 1870. However, Pius IX refused to recognize the loss of temporal power and became a “prisoner” in the Vatican; his successors followed his example. The so-called Roman Question was only resolved in 1929 by the Lateran Treaty, which, among other things, established Vatican City.