The Patrimony of Saint Peter (Latin: Patrimonium Sancti Petri) originally designated the landed possessions and revenues of various kinds that belonged to the apostolic Holy See.
During his reign, Pope Sylvester became the owner of properties in Italy, Sicily, Antioch, Asia Minor, in the region around Hippo in Numidia, Armenia, and Upper Mesopotamia.
[1] Apart from a number of scattered possessions in Dalmatia and southern Gaul, the patrimonies were naturally for the most part situated in Italy and on the adjacent islands.
The revenues from these properties in Sicily and Lower Italy were estimated at three and one-half talents of gold in the eighth century, when Byzantine Emperor Leo the Isaurian confiscated them.
[1] But the patrimonies in the vicinity of Rome (the successors to the classical latifundia in the Ager Romanus), which had begun to form in the 7th century, were the most numerous.
Most of the remote patrimonies were lost in the eighth century, so the patrimonia around Rome began to be managed with especial care, headed up by deacons directly subordinate to the pope.
Revenues from the patrimonies were used for administration, to maintain and build churches, to equip convents, run the papal household and support the clergy, but also to a great extent to relieve public and private want.
Gregory also spent large sums ransoming captives from the Lombards, and commended one of the bishops for breaking up and selling church plate for that purpose.
Cassiodorus, as praefectus praetorio under the Ostrogothic supremacy, entrusted the care of temporal affairs to Pope John II.
Thenceforth for two centuries the popes were loyal supporters of the Byzantine government against the encroachments of the Lombards, and were all the more indispensable, because after 603 the Senate disappeared.
The strange shape which the States of the Church assumed from the beginning is explained by the fact that these were the districts in which the population of central Italy had defended itself to the very last against the Lombards.
Charles Martel had on a former occasion failed to respond to the entreaties of Gregory III, but meanwhile the relations between the Frankish rulers and the popes had become more intimate.
Pope Zachary had only recently (751), at Pepin's accession to the Merovingian throne, spoken the word that removed all doubts in favour of the Carolingian mayor of the palace.
Accordingly, Stephen II secretly sent a letter to king Pepin by pilgrims, soliciting his aid against Aistulf and asking for a conference.
This became imperative, when several embassies attempted by peaceful means to induce the Lombard king to give up his conquests but returned without accomplishing their mission.
This document has not been preserved, but a number of citations during the decades immediately following indicate its contents, and it is likely that it was the source of the much interpolated Fragmentum Fantuzzianum, which probably dates from 778 to 80.
In the summer of 754 Pepin and the pope began their march into Italy, and forced King Aistulf, who had shut himself up in his capital, to sue for peace.
The Lombard promised to give up the cities of the exarchate and of the Pentapolis, which had been last conquered, to make no further attacks upon or to evacuate the Duchy of Rome and the northwest Italian districts of Venetia and Istria, and also acknowledged the sovereignty of the Franks.
Adrian I complained that the Lombard king Desiderius had invaded the territories of the States of the Church, and reminded Charlemagne of the promise made at Quiercy.
The Duchy of Rome (which had not been mentioned in the earlier documents) heads the list, followed by the exarchate and the Pentapolis, augmented by the cities which Desiderius had agreed to surrender at the beginning of his reign (Imola, Bologna, Faenza, Ferrara, Ancona, Osimo and Umana); next the patrimonies were specified in various groups: in the Sabine, in the Spoletan and Beneventan districts, in Calabria, in Tuscany and in Corsica.
Charlemagne, however, in his quality of "Patricius", wanted to be considered as the highest court of appeal in criminal cases in the States of the Church.
He promised on the other hand to protect freedom of choice in the election of the pope, and renewed the alliance of friendship that had been previously made between Pepin and Stephen II.
In 787 Charlemagne further enlarged the States of the Church by new donations: Capua and a few other frontier cities of the Duchy of Benevento, besides several cities in Lombardy, Tuscany, Populonia, Roselle, Sovana, Toscanella, Viterbo, Bagnorea, Orvieto, Ferento, Orchia, Marta and lastly Città di Castello appear to have been added at that time.
[7] From the early 13th century, the Patrimony of Saint Peter was one of the four provinces established by Pope Innocent III as a division of the Ecclesiastical States.