Byzantine Italy in the context of "Maritime Venice"

The Exarchate of Ravenna (Latin: Exarchatus Ravennatis; Greek: Ἐξαρχᾶτον τῆς Ῥαβέννης, romanized: Exarcháton tís Ravénis), also known as the Exarchate of Italy, was an exarchate (administrative district) of the Byzantine Empire comprising, between the 6th and 8th centuries, the territories under the jurisdiction of the exarch of Italy (exarchus Italiae) resident in Ravenna. The term is used in historiography in a double sense: "exarchate" in the strict sense denotes the territory under the direct jurisdiction of the exarch, i.e. the area of the capital Ravenna, but the term is mainly used to designate all the Byzantine territories in continental and peninsular Italy. According to the legal sources of the time, these territories constituted the so-called Provincia Italiae, on the basis of the fact that they too, until at least the end of the 7th century, fell under the jurisdiction of the exarch and were governed by duces or magistri militum under him.

The exarchate was established around 584, the year in which the presence of an exarch in Ravenna is attested for the first time, as a consequence of the perpetual state of war with the Lombards (who in the meantime had stolen approximately two thirds of the Byzantine lands in continental and peninsular Italy), which necessarily entailed the militarization of Byzantine Italy. The necessities of war pushed military commanders to centralize powers, thus depriving the civil authorities which are no longer attested by sources starting from the second half of the 7th century. Thus the separation of civil and military powers introduced by Diocletian and Constantine disappeared. Byzantine Italy was divided into various military districts governed by duces or magistri militum dependent on the exarch of Italy, the military governor with full powers chosen by the emperor from among his generals or trusted officials to govern and defend the remaining territories italics. These districts gradually evolved into increasingly autonomous duchies.

The Catepanate of Italy (Greek: κατεπανίκιον Ἰταλίας, Katepaníkion Italías) was a province (theme) of the Byzantine Empire, that existed from c. 965 until 1071. It was headed by a governor (katepano) with both civil and military powers. At its greatest extent, it comprised mainland Italy south of a line drawn from Monte Gargano to the Gulf of Salerno. North of that line, Amalfi and Naples also maintained allegiance to Byzantine Emperors through the katepano. The Italian region of Capitanata derives its name from the term katepanikion (a province under the jurisdiction of katepano).

Constantine X Doukas or Ducas (Greek: Κωνσταντῖνος Δούκας, romanized: Kōnstantīnos Doúkās; c. 1006 – 23 May 1067), was Byzantine emperor from 1059 to 1067. He was the founder of the Doukid dynasty. During his reign, the Normans took over much of the remaining Byzantine territories in Italy, while in the Balkans the Hungarians occupied Belgrade. He also suffered defeats by the Seljuk sultan Alp Arslan.

The Patriarchate of Grado, also known as the Patriarchate of New Aquileia, was an episcopal see and ecclesiastical province in northeastern Italy, centered in Grado, on the northern coasts of the Adriatic Sea. It was created as a result of an internal schism within the ancient Patriarchate of Aquileia. In 568, after the Lombard conquest of Aquileia, patriarch Paulinus left the city and fled to the minor coastal, but better protected town of Grado, that still remained under the Byzantine rule. First patriarchs who resided in Grado continued to exercise their jurisdiction over bishops in Lombard-held parts of the province, but at the very beginning of the 7th century a schism occurred, when bishops in Lombard regions elected their separate patriarch (Ioannes), who took residence in the old Aquileia, thus becoming rival to Candidianus of Grado. From that time, the region was divided between two distinctive jurisdictions: the Patriarchate of Old Aquileia in Lombard-held lands, and the Patriarchate of New Aquileia, with residence in Grado and jurisdiction over Byzantine possessions in the northern Adriatic (including Venice and Istria).

Initially, the patriarchs in Grado continued to claim the title of Patriarch of Aquileia, but in the early 700s it was gradually dropped and then officially changed to Patriarch of Grado. Throughout their history, the patriarchs of Grado, with the support of Venice and the Byzantines, fought military, politically, and ecclesiastically the patriarchs of old Aquileia, who were supported by the Lombards, and later the Carolingians and the Holy Roman Emperors.

The Patriarchate of Old Aquileia was created at the beginning of the 7th century, as a result of an internal schism within the Patriarchate of Aquileia. It was centered in the old Aquileia, that was held by the Lombards, while the rival Patriarchate of New Aquileia in Grado was under the Byzantine rule. Residence of the patriarchs of Old Aquileia was later moved, first to the city of Cormons, then to Cividale, and finally to Udine. Since 1077, patriarchs of Old Aquileia were also temporal lords of the Patriarchal State of Aquileia, that was annexed by the Venetian Republic in the first half of the 15th century, while the Patriarchate of Old Aquileia continued to exist as an ecclesiastical institution until 1751, when it was also abolished.