Mediolanum in the context of "Milan"

In modern historiography, the Western Roman Empire were the Roman Empire's western provinces, collectively, during any period in which they were administered separately from the eastern provinces by a separate, independent imperial court. Particularly during the period from AD 395 to 476, there were separate, coequal courts dividing the governance of the empire into the Western provinces and the Eastern provinces with a distinct imperial succession in the separate courts. The terms Western Roman Empire and Eastern Roman Empire were coined in modern times to describe political entities that were de facto independent; contemporary Romans did not consider the Empire to have been split into two empires but viewed it as a single polity governed by two imperial courts for administrative expediency. The Western Empire collapsed in 476, and the Western imperial court in Ravenna disappeared by 554, at the end of Justinian's Gothic War.

Though there were periods with more than one emperor ruling jointly before, the view that it was impossible for a single emperor to govern the entire Empire was institutionalized by emperor Diocletian following the disastrous civil wars and disintegrations of the Crisis of the Third Century. He introduced the system of the Tetrarchy in 286, with two senior emperors titled Augustus, one in the East and one in the West, each with an appointed subordinate and heir titled Caesar. Though the tetrarchic system would collapse in a matter of years, the East–West administrative division would endure in one form or another over the coming centuries. As such, the unofficial Western Roman Empire would exist intermittently in several periods between the 3rd and 5th centuries. Some emperors, such as Constantine I and Theodosius I, governed, if briefly, as the sole Augustus across the Roman Empire. On the death of Theodosius in 395, the empire was divided between his two infant sons, with Honorius as his successor in the West governing briefly from Mediolanum then from Ravenna, and Arcadius as his successor in the East governing from Constantinople.

Ravenna (/rəˈvɛnə/ rə-VEN-ə; Italian: [raˈvenna], also locally [raˈvɛn(n)a] ; Romagnol: Ravèna, Ravêna) is the capital city of the Province of Ravenna, in the Emilia-Romagna region of Northern Italy. It was the capital city of the Western Roman Empire during the 5th century until its collapse in 476, after which it served as the capital of the Ostrogothic Kingdom and then the Byzantine Exarchate of Ravenna. It has 156,444 inhabitants as of 2025.

Initially settled by the Umbri people, Ravenna came under Roman Republic control in 89 BC. Octavian built the military harbor of Classis at Ravenna, and the city remained an important seaport on the Adriatic until the early Middle Ages. The city prospered under imperial rule. In 401, Western Roman emperor Honorius moved his court from Mediolanum to Ravenna; it then served as capital of the empire for most of the 5th century.

The Edict of Milan (Latin: Edictum Mediolanense; Greek: Διάταγμα τῶν Μεδιολάνων, Diatagma tōn Mediolanōn) was the February 313 agreement to treat Christians benevolently within the Roman Empire. Western Roman Emperor Constantine I and Emperor Licinius, who controlled the Balkans, met in Mediolanum (modern-day Milan) and, among other things, agreed to change policies towards Christians following the edict of toleration issued by Emperor Galerius two years earlier in Serdica. The Edict of Milan gave Christianity legal status and a reprieve from persecution but did not make it the state church of the Roman Empire, which occurred in AD 380 with the Edict of Thessalonica, when Nicene Christianity received normative status.

The document is found in Lactantius's De mortibus persecutorum and in Eusebius of Caesarea's History of the Church with marked divergences between the two. Whether or not there was a formal 'Edict of Milan'  is no longer really debated among scholars, who generally reject the story as it has come down in church history.

The sack of Rome on 24 August 410 AD was undertaken by the Visigoths led by their king, Alaric. At that time, Rome was no longer the administrative capital of the Western Roman Empire, having been replaced first by Mediolanum (now Milan) in 286 and then by Ravenna in 402. Nevertheless, the city of Rome retained a paramount position as "the eternal city" and a spiritual center of the Empire. This was the first time in almost 800 years that Rome had fallen to a foreign enemy, and the sack was a major shock to contemporaries, friends and foes of the Empire alike.

The sacking of 410 is seen as a major landmark in the fall of the Western Roman Empire. St. Jerome, living in Bethlehem, wrote: "the city which had taken the whole world was itself taken".

The Insubres or Insubri were an ancient Celtic population settled in Insubria, in what is now the Italian region of Lombardy. They were the founders of Mediolanum (Milan). Though completely Gaulish at the time of Roman conquest, they were the result of the fusion of pre-existing Ligurian and Celtic population (Golasecca culture) with Gaulish tribes.