Italia was the name of the Italian Peninsula during the Roman era. It was not a province, but the territory of the city of Rome, thus having a special status. Italy and its borders expanded over time, until Augustus finally organized it as an administrative division constisting of eleven regiones (from the Alps to the Ionian Sea). The three islands of Corsica, Sardinia and Sicily (including Malta) were adeed to Italy by Diocletian in the year 292 AD. Roman Italy remained united until the sixth century, when it was divided between the Byzantine Empire and territories of the Germanic peoples. Since then, Italia remained divided for nearly thirteen centuries until 1861 when it was reunited in a similar way in the modern Kingdom of Italy.
After having been for centuries the heart of the Empire, from the 3rd century the government and the cultural center began to move eastward: first the Edict of Caracalla in 212 AD extended Roman citizenship to all free men within the imperial boundaries, then Christianity became the dominant religion during Constantine's reign (306–337) raising the power of other Eastern political centres. Although not founded as a capital city in 330, Constantinople gained in importance. It finally gained the rank of eastern capital when given an urban prefect in 359 and the senators who were clari became senators of the lowest rank as clarissimi.
As a result, Italy began to decline in favour of the provinces, which resulted in the division of the Empire into two administrative units in 395: the Western Roman Empire, with capital Mediolanum (now Milan), and the Byzantine Empire, with a capital in Constantinople (now Istanbul). In 402, the capital was moved to Ravenna from Milan, confirming the decline of the city of Rome (which was sacked in 410 for the first time in seven centuries).
The name Italia covered an area whose borders evolved over time. According to Strabo's Geographica, before the expansion of the Roman Republic, the name was used by Greeks to indicate the land between the strait of Messina and the line connecting the gulf of Salerno and gulf of Taranto (corresponding roughly to the current region of Calabria); later the term was extended by Romans to include the Italian Peninsula up to the Rubicon, a river located between Northern and Central Italy.
In 49 BC, with the Lex Roscia Julius Caesar gave Roman citizenship to the people of the Cisalpine Gaul, while in 42 BC the hitherto existing province was abolished, thus extending Italy to the north up to the southern foot of the Alps.
Under Augustus, the peoples of today's Aosta Valley and of the western and northern Alps were subjugated (so the western border of Roman Italy was moved to the Varus river), and the Italian eastern border was brought to the Arsia in Istria;. Finally, in the late 3rd century, Italy came to include the islands of Corsica and Sardinia and Sicily, as well as Raetia and part of Pannonia to the north. The city of Emona (modern Ljubljana, Slovenia) was the easternmost town of Italy.
At the beginning of the imperial era, Italy was a collection of territories with different political statuses. Some cities, called municipia, had some independence from Rome, while others, the coloniae, were founded by the Romans themselves. Around 7 BC, Augustus divided Italy into eleven regiones, as reported by Pliny the Elder in his Naturalis Historia:
- Regio I Latium et Campania
- Regio II Apulia et Calabria
- Regio III Lucania et Bruttium
- Regio IV Samnium
- Regio V Picenum
- Regio VI Umbria et Ager Gallicus
- Regio VII Etruria
- Regio VIII Aemilia
- Regio IX Liguria
- Regio X Venetia et Histria
- Regio XI Transpadana
Italy was privileged by Augustus and his heirs, with the construction, among other public structures, of a dense network of Roman roads. The Italian economy flourished: agriculture, handicraft and industry had a sensible growth, allowing the export of goods to the other provinces. The Italian population may have grown as well: three census were ordered by Augustus, to record the number of Roman citizens throughout the empire. The surviving totals were 4,063,000 in 28 BC, 4,233,000 in 8 BC, and 4,937,000 in AD 14, but it is still debated whether these counted all citizens, all adult male citizens, or citizens sui iuris. Estimates for the population of mainland Italy, including Cisalpine Gaul, at the beginning of the 1st century range from 6,000,000 according to Karl Julius Beloch in 1886, to 14,000,000 according to Elio Lo Cascio in 2009.
Diocletian and Constantinian re-organizations
During the Crisis of the Third Century the Roman Empire nearly collapsed under the combined pressures of invasions, military anarchy and civil wars, and hyperinflation. In 284, emperor Diocletian restored political stability. He carried out thorough administrative reforms to maintain order. He created the so-called Tetrarchy whereby the empire was ruled by four co-emperors (two senior ones called Augusti and two junior ones called Caesars). He decreased the size of the Roman provinces by doubling their number to reduce the power of the provincial governors. He grouped the provinces into several dioceses (Latin: diocesis) and put them under the supervision of the imperial vicarius (vice, deputy), who was the head of the diocese. During the Crisis of the Third Century the importance of Rome declined because she was far from the troubled frontiers. Diocletian designated four imperial seats, one of each emperor, which were closer to the frontiers. The Augusti, Diocletian and Maximian, who were responsible for the East and West and respectively, established themselves at Nicomedia, in north-western Anatolia (closer to the Persian frontier in the east) and Milan, in northern Italy (closer to the European frontiers) respectively. The seats of the Caesars were Augusta Treverorum (on the River Rhine frontier) for Constantius Chlorus and Sirmium (on the River Danube frontier) for Galerius.
Under Diocletian Italy became the Dioecesis Italiciana. It included Rhaetia). It was subdivided the following provinces:
- Liguria (today's Liguria and western Piedmont)
- Transpadana (western Piedmont and Lombardy)
- Rhaetia (eastern Switzerland, western and central Austria and part of southern Germany)
- Venetia et Histria (today's Veneto, Friuli-Venezia Giulia and Trentino Alto Adige)
- Aemilia (Emilia-Romagna)
- Tuscia (Etruria) et Umbria (Tuscany and Umbria)
- Flaminia (Picenum and the former Ager Gallicus and , in today's Marche)
- Latium et Campania (the coastal parts of Lazio and Campania)
- Samnium (Abruzzo, Molise and Irpinia)
- Apulia et Calabria (today's Apulia)
- Lucania et Bruttium (Basilicata and Calabria)
- Sicilia (Sicily)
- Corsica et Sardinia
Constantine the Great subdivided the empire into four Praetorian prefectures. The Diocesis Italiciana became the Praetorian prefecture of Italy (praefectura praetoria Italiae), and was subdivided into two dioceses. It still included Rhaetia. The two dioceses and their provinces were:
Diocesis Italia annonaria ( Italy of the annona - its inhabitants had to provide the administration in Milan and the troops stationed in that city the annona - food, wine and timber).
- Alpes Cottiae (modern Liguria and part of Piedmont)
- Liguria (western Lombardy and part of Piedmont)
- Venetia et Histria (Istria [which is now part of Croatia, Slovenia and Italy], Friuli-Venezia Giulia, Trentino Alto Adige, Veneto and eastern and central Lombardy)
- Raetia I (eastern Switzerland and western Austria)
- Rhaetia II (central Austria and part of southern Germany)
- Aemilia (the Emilia part of Emilia-Romagna)
- Flaminia et Picenum Annonarium (Romagna and northern Marche)
Diocesis Italia Suburbicaria ( Italy "under the government of the urbs", i.e. Rome)
- Tuscia (Etruria) et Umbria (Tuscany, Umbria and the northern part of coastal Lazio)
- Picenum suburbicarium (Piceno, in southern Marche)
- Valeria Sabina (the modern province of Rieti, other areas of Lazio and areas of Umbria and Abruzzo)
- Campania (central and southern coastal Lazio and coastal Campania except for the modern province of Salerno)
- Samnium (Abruzzo, Molise and the mountain areas of modern Campania; i.e., the modern provinces on Benevento and Avellino and part of the province of Caserta)
- Apulia et Calabria (today's Apulia)
- Lucania et Bruttium (modern Calabria, Basilicata and the province of Salerno in modern Campania)
- Sicilia (Sicily)
Western Roman Empire
In 330 AD, Constantine inaugurated Constantinople. He established an the imperial court, Senate, financial and judicial administrations, as well as the military structures. The new city, however, did not receive an urban prefect until 359, which raised it to the status of eastern capital. After the death of Theodosius in 395 AD and the subsequent division of the empire, Italy became part of the Western Roman Empire. Then came the years of the barbarian invasions, and the western capital was moved from Mediolanum to Ravenna in 402 AD. Alaric, king of Visigoths, sacked Rome itself in 410 AD; something that hadn't happened for eight centuries. Northern Italy was attacked by Attila's Huns, and Rome was sacked again by the Vandals under the command of Genseric in 455 AD.
According to Notitia Dignitatum, one of the very few surviving documents of Roman government updated to the 420s, Roman Italy was governed by a praetorian prefect, Prefectus praetorio Italiae (who also governed the Diocese of Africa and the Diocese of Pannonia), one vicarius, and one comes rei militaris. The regions of Italy were governed at the end of the fourth century by eight consulares (Venetiae et Histriae, Aemiliae, Liguriae, Flaminiae et Piceni annonarii, Tusciae et Umbriae, Piceni suburbicarii, Campaniae, and Siciliae), two correctores (Apuliae et Calabriae and Lucaniae et Bruttiorum) and seven praesides (Alpium Cottiarum, Rhaetia Prima and Secunda, Samnii, Valeriae, Sardiniae, and Corsicae). Later, the Germanic successor states under Odoacer and Theodoric the Great continued to use the Roman administrative machinery, as well as being nominal subjects of the Eastern emperor at Constantinople. The "Prefecture of Italy" thus survived, and came again into Roman hands in the course of Justinian's Gothic War.
In the fifth century, with the Emperors controlled by their barbarian generals, the Western imperial government maintained weak control over Italy, whose coasts were periodically under attack. In 476 AD, with the abdication of Romulus Augustulus, the Western Roman Empire had formally fallen unless one considers Julius Nepos, the legitimate emperor recognized by Constantinople as the last. He was assassinated in 480. He may have been recognized by Odoacer. Italy remained under Odoacer and his Kingdom of Italy, and then under the Ostrogothic Kingdom. In 535 Eastern Roman Emperor Justinian I invaded Italy which suffered twenty years of disastrous war. In August 554, Justinian issued a Pragmatic sanction which maintained most of the organization of Diocletian. As a result of the Lombard invasion in 568 AD, the Byzantines lost most of Italy, except the territories of the Exarchate of Ravenna - a corridor from Venice to Lazio - and footholds in the south Naples and the toe and heel of the peninsula.
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