The Sea Battle That Ended the Republic
By 100 BC, Rome had already pushed its rule from the Italian peninsula across most of the Mediterranean and beyond. But it was tearing itself apart from the inside with civil wars and political conflict.
It came to a head at the Battle of Actium in 31 BC, where Octavian defeated Mark Antony and Cleopatra. The conquest of the Ptolemaic Kingdom in Egypt followed.
In 27 BC the Roman Senate granted Octavian overarching military power, called imperium, along with a new title: Augustus. That moment made him the first Roman emperor and turned a republic into something else. The territories were reorganised into senatorial provinces, run by proconsuls chosen annually by lot, and imperial provinces, which belonged to the emperor and were run by his legates.
Two Hundred Years of Quiet
The first two centuries of the empire brought stability and prosperity on a scale the ancient world had not seen. It has a name: the Pax Romana, the Roman Peace.
Rome reached its greatest territorial extent under Trajan, who ruled from 98 to 117 AD. That was the high-water mark, and everything after it was a slower story.
The trouble started under Commodus, who ruled from 180 to 192. From there the decline set in, and the century that followed would test whether the empire could survive at all.
The Fifty Years That Nearly Ended Rome
In the 3rd century the empire went through a crisis that lasted fifty years and genuinely threatened its existence. Civil war, plagues and barbarian invasions arrived together.
Whole regions broke away. The Gallic and Palmyrene empires split off and governed themselves, while a rapid series of short-lived emperors cycled through Rome.
Aurelian, ruling from 270 to 275, reunified the empire. The civil wars finally ended with the victory of Diocletian, who ruled from 284 to 305 and set up two separate imperial courts, one in the Greek East and one in the Latin West. That split would matter enormously later.
The Half That Never Fell
Constantine the Great, ruling from 306 to 337, was the first Christian emperor. In 330 he moved the imperial seat from Rome to Byzantium and renamed the city Constantinople.
Meanwhile the Migration Period brought huge invasions by Germanic peoples and the Huns. Ravenna fell to the Germanic Herulians, and in 476 Odoacer deposed Romulus Augustus. The Western Roman Empire was finished.
The Eastern Roman Empire, later known as the Byzantine Empire, simply carried on. It survived for another thousand years with Constantinople as its sole capital, until the city fell in 1453. By the late 3rd century the empire had already been divided many times, so the split that saved half of it was nothing new.
Why Rome Never Really Left
The empire lasted long enough and stretched far enough that its institutions and culture shaped everything that came after: language, religion, art, architecture, literature, philosophy, law and forms of government across all its former territories.
There is a longer chain too. The rediscovery of classical science and technology in medieval Europe, which had formed the basis for Islamic science, fed directly into the Scientific Renaissance and then the Scientific Revolution.
And Rome's republican institutions, the ones Augustus quietly replaced, had the strangest afterlife of all. They influenced the Italian city-state republics of the medieval period, the early United States, and modern democratic republics today.
