The Exarchate of Ravenna or of Italy was a centre of Byzantine power in Italy, from the end of the 6th century to 751, when the last Exarch (Byzantine governor) was put to death by the Emperor's enemies in Italy, the Lombards.
Ravenna became the capital of the Western Roman Empire in 402 under Honorius, due to its fine harbour with access to the Adriatic and its ideal defensive location amidst impassable marshes. The city remained the capital of the Empire until its dissolution in 476, when it became the capital of Odoacer, and then of the Ostrogoths under King Theodoric. It remained the capital of the Ostrogothic Kingdom, but in 540 during the Gothic War (535–554), Ravenna was occupied by the great Byzantine general Belisarius. After the Roman reconquest it became the seat of the provincial governor. At that time, the administrative structure of Italy followed, with some modifications, the old system established by Emperor Diocletian and retained by Odoacer and the Goths.
Emperor Justin II tried to take advantage of this, and in 576 he sent his son-in-law, Baduarius, to Italy. However, he was defeated and killed in battle, and the continuing crises in the Balkans and the East meant that another imperial effort at reconquest was not possible. Because of the Lombard incursions, the Roman possessions had fragmented into several isolated territories, and in 580, Emperor Tiberius II reorganized them into five provinces, now termed in Greek, eparchies: the Annonaria in northern Italy around Ravenna, Calabria, Campania, Emilia and Liguria, and the Urbicaria around the city of Rome (Urbs). Thus by the end of the sixth century the new order of powers had settled into a stable pattern. Ravenna, governed by its exarch, who held civil and military authority in addition to his ecclesiastical office, was confined to the city, its port and environs as far north as the Po, beyond which lay territory of the duke of Venice, nominally in imperial service, and south to the Marecchia River, beyond which lay the Pentapolis on the Adriatic, also under a duke nominally representing the Emperor of the East.
The exarchate was organised into a group of duchies (i.e the Duchy of Rome, Duchy of Venetia, Duchy of Calabria, Lucania, Spoleto etc) which were mainly the coastal cities in the Italian peninsula since the Lombards held the advantage in the hinterland.
The civil and military head of these imperial possessions, the exarch himself, was the representative at Ravenna of the emperor in Constantinople. The surrounding territory reached from the boundary with Venice in the north to the Pentapolis at Rimini, the border of the "five cities" in the Marches along the Adriatic coast; and reached even cities not on the coast, as Forlì for instance. All this territory lies on the eastern flank of the Apennines; this was under the exarch's direct administration and formed the Exarchate in the strictest sense. Surrounding territories were governed by dukes and magistri militium more or less subject to his authority. From the perspective of Constantinople, the Exarchate consisted of the province of Italy.
The Exarchate of Ravenna was not the sole Byzantine province in Italy. Byzantine Sicily formed a separate government, and Corsica and Sardinia, while they remained Byzantine, belonged to the Exarchate of Africa.
The Lombards had their capital at Pavia and controlled the great valley of the Po. The Lombard wedge in Italy spread to the south, and established duchies at Spoleto and Beneventum; they controlled the interior, while Byzantine governors more or less controlled the coasts.
The Piedmont, Lombardy, the interior mainland of Venetia, Tuscany and the interior of Naples belonged to the Lombards, and bit by bit the Imperial representative in Italy lost all genuine power, though in name he controlled areas like Liguria (completely lost in 640 to the Lombards), or Naples and Calabria (being overrun by the Lombard duchy of Benevento). In Rome, the pope was the real master.
At the end, ca 740, the Exarchate consisted of Istria, Venetia (except for the lagoon of Venice itself, which was becoming an independent protected city-state, the forerunner of the future republic of Venice), Ferrara, Ravenna (the exarchate in the limited sense), with the Pentapolis, and Perugia.
These fragments of the province of Italy, as it was when reconquered for Justinian, were almost all lost, either to the Lombards, who finally conquered Ravenna itself about 750, or by the revolt of the pope, who finally separated from the Empire on the issue of the iconoclastic reforms.
The relationship between the Pope in Rome and the Exarch in Ravenna was a dynamic that could hurt or help the empire. The Papacy could be a vehicle for local discontent. The old Roman senatorial aristocracy resented being governed by an Exarch who was considered by many a meddlesome foreigner. Thus the exarch faced threats from without as well as from within, hampering much real progress and development.
In its internal history the exarchate was subject to the splintering influences which were leading to the subdivision of sovereignty and the establishment of feudalism throughout Europe. Step by step, and in spite of the efforts of the emperors at Constantinople, the great imperial officials became local landowners, the lesser owners of land were increasingly kinsmen or at least associates of these officials, and new allegiances intruded on the sphere of imperial administration. Meanwhile the necessity for providing for the defence of the imperial territories against the Lombards led to the formation of local militias, who at first were attached to the imperial regiments, but gradually became independent, as they were recruited entirely locally. These armed men formed the exercitus romanae militiae, who were the forerunners of the free armed burghers of the Italian cities of the Middle Ages. Other cities of the exarchate were organized on the same model.
During the 6th and 7th centuries the growing menace of the Lombards and the Franks, and the split between eastern and western Christendom caused by Iconoclasm and the acrimonious rivalry between the Pope and the patriarch of Constantinople, made the position of the exarch more and more untenable.
Ravenna remained the seat of the exarch until the revolt of 727 over Iconoclasm. Eutychius, the last exarch of Ravenna, was killed by the Lombards in 751. The exarchate was reorganized as the Catapanate of Italy headquartered in Bari which was lost to the Saracens in 858 and only recovered in 878.
When in 756 the Franks drove the Lombards out, Pope Stephen II claimed the exarchate. His ally Pippin the Younger, King of the Franks, donated the conquered lands of the former exarchate to the Papacy in 756; this donation, which was confirmed by his son Charlemagne in 774, marked the beginning of the temporal power of the popes as the Patrimony of Saint Peter. The archbishoprics within the former exarchate, however, had developed traditions of local secular power and independence, which contributed to the fragmenting localization of powers. Three centuries later, that independence would fuel the rise of the independent communes.
So the Exarchate disappeared, and the small remnants of the imperial possessions on the mainland, Naples and Calabria, passed under the authority of the Catapan of Italy, and when Sicily was conquered by the Arabs in the 9th century the remnants were erected into the themes of Calabria and Langobardia. Istria at the head of the Adriatic was attached to Dalmatia.