Lazio

The emperor Augustus officially united almost all of present-day Italy into a single geo-political entity, Italia, dividing it into eleven regions. The part of todays Lazio south of the Tiber river – together with the present region of Campania immediately to the southeast of Lazio and the seat of Neapolis – became Region I (Latium et Campania), while modern Upper Lazio became part of Regio VII - Etruria, and todays Province of Rieti joined Regio IV - Samnium.

After the Gothic conquest of Italy at the end of the fifth century, modern Lazio became part of the Ostrogothic Kingdom, but after the Gothic War between 535 and 554 and the Byzantine conquest, this region regained its freedom, because the "Roman Duchy" became the property of the Eastern Emperor. However, the long wars against the Longobards weakened the region. With the Donation of Sutri in 728, the Bishop of Rome acquired the first territory in the region beyond the Duchy of Rome.

The strengthening of the religious and ecclesiastical aristocracy led to continuous power struggles between secular lords (Baroni) and the Pope until the middle of the 16th century. Innocent III tried to strengthen his own territorial power, wishing to assert his authority in the provincial administrations of Tuscia, Campagna and Marittima through the Churchs representatives, in order to reduce the power of the Colonna family. Other popes tried to do the same. During the period when the papacy resided in Avignon, France (1309–1377), the feudal lords power increased due to the absence of the Pope from Rome. Small communes, and Rome above all, opposed the lords increasing power, and with Cola di Rienzo, they tried to present themselves as antagonists of the ecclesiastical power. However, between 1353 and 1367, the papacy regained control of Lazio and the rest of the Papal States.

From the middle of the 16th century, the papacy politically unified Lazio with the Papal States, so that these territories became provincial administrations of St. Peters estate; governors in Viterbo, in Marittima and Campagna, and in Frosinone administered them for the papacy.

Lazio comprised the short-lived Roman Republic, in which it became a puppet state of the First French Republic under the forces of Napoleon Bonaparte. The Republic existed from 15 February 1798 until Lazio was returned to the Papal States in October 1799. In 1809, Lazio was annexed to the French Empire under the name of Department of Tibre, but returned under the Pope in 1815.

On 20 September 1870 the capture of Rome, during the reign of Pope Pius IX, and Frances defeat at Sedan, completed Italian unification, and Lazio was incorporated into the Kingdom of Italy.

In 1927 the territory of the Province of Rieti, belonging to Umbria and Abruzzo, joined Lazio.