The Roman Empire: Power, Politics, and Decline
For almost five hundred years after Augustus became the first Roman emperor in 27 BCE, the Roman Empire was the largest, wealthiest, and most powerful state in the Western world. It stretched from Hadrian’s Wall in northern Britain to the Euphrates, from the Rhine and Danube to the Atlas Mountains, and it gave the Mediterranean basin two centuries of relative peace, prosperity, and cultural integration — the Pax Romana. The Roman Empire was the political framework within which Christianity was born and grew to dominance, the legal system that would later be revived in the Renaissance, and the engineering template that the entire Western world would eventually inherit.
This cluster page walks you through the history of the Roman Empire: the early Principate, the high Empire, the crisis of the third century, the late Empire, and the eventual fall of the western half in 476 CE. It links out to Julius Caesar, the Punic Wars, Roman Engineering, and the Daily Life in Ancient Rome cluster.
The Founding of the Empire (27 BCE – 14 CE)
The Republic collapsed into civil war in the first century BCE. After the assassination of Julius Caesar on the Ides of March, 44 BCE, his adopted son Octavian fought a war against Caesar’s former allies Mark Antony and Cleopatra, defeated them at the naval Battle of Actium in 31 BCE, and returned to Rome as the undisputed master of the Roman world.
In 27 BCE, the Senate awarded Octavian the title Augustus, “the revered one,” and he became the first Roman emperor. In a brilliant piece of political theater, Augustus claimed to have restored the Republic while quietly concentrating all real power in his own hands. He kept the old Republican magistracies on the books, but the real decisions were made by the emperor, the imperial bureaucracy, and the imperial army.
The historian Tacitus famously quipped that Augustus had “swept the streets of a noxious old Republic and converted it into a Principate.” The word principate comes from princeps, “first citizen,” the title Augustus preferred to rex, “king.” The more honest term, imperator, gave us the modern word emperor.
The Julio-Claudians and the Flavians (14–96 CE)
Augustus ruled for over forty years. He was succeeded by his stepson Tiberius (14–37 CE), who was a competent but unpopular emperor; by the mad Caligula (37–41 CE), assassinated at twenty-eight; by Claudius (41–54 CE), the historian emperor who conquered Britain; and by Nero (54–68 CE), who murdered his mother, his wife, and his teacher, kicked his pregnant wife to death, blamed the Great Fire of Rome on the Christians, and was forced to commit suicide.
The year 69 CE, the “Year of the Four Emperors,” saw the end of the Julio-Claudian dynasty and the beginning of the Flavians. Vespasian, an Italian general, won the civil war and founded a new dynasty. He was succeeded by his sons Titus and Domitian, and the dynasty ended with Domitian’s assassination in 96 CE.
The High Empire and the “Five Good Emperors” (96–180 CE)
The high point of the Roman Empire came under the so-called “Five Good Emperors” — Nerva, Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius. Nerva (96–98 CE) was a brief, transitional reign. Trajan (98–117 CE) was a military emperor who expanded the empire to its greatest extent, conquering Dacia (modern Romania), Armenia, and Mesopotamia. Hadrian (117–138 CE) was a poet and a builder who withdrew from Trajan’s eastern conquests, consolidated the empire’s borders, and built Hadrian’s Wall in northern Britain. Antoninus Pius (138–161 CE) presided over a peaceful and prosperous reign. Marcus Aurelius (161–180 CE) was the philosopher-emperor whose Meditations are still widely read; he spent most of his reign on the Danube frontier fighting the Marcomannic Wars.
The Crisis of the Third Century (180–284 CE)
The third century was the most dangerous period in Roman history. The empire was attacked on every frontier — by the Germanic tribes in the north, the Sassanid Persians in the east, and the Berber and other desert peoples in the south. Plague swept through the empire. The currency was debased. The army, increasingly Germanic, made and unmade emperors at will; in the fifty years between 235 and 284, more than twenty emperors were recognized, most of them killed by their own soldiers.
The crisis was eventually resolved by the emperor Diocletian (284–305 CE), who divided the empire into eastern and western halves, each with its own emperor, and introduced a series of reforms that stabilized the economy and the administration. Diocletian also launched the last great persecution of the Christians, which was reversed by his successor Constantine.
Constantine and Christianity (306–337 CE)
Constantine, the son of one of Diocletian’s colleagues, reunited the empire and converted to Christianity after his victory at the Battle of the Milvian Bridge in 312 CE. In 313 he issued the Edict of Milan, which granted Christianity legal status, and in 330 he moved the capital of the empire from Rome to the old Greek city of Byzantium, which he renamed Constantinople. Constantinople would remain the capital of the Eastern Roman (Byzantine) Empire for more than a thousand years.
The Late Empire (337–476 CE)
After Constantine, the empire slowly weakened. The western half was increasingly unable to defend its long frontiers from the Germanic peoples — the Visigoths, Ostrogoths, Vandals, Franks, and others — who were pushed westward by the arrival of the Huns from central Asia. In 410 CE, the Visigoths under Alaric sacked Rome. In 455 CE, the Vandals sacked it again. In 476 CE, the Germanic king Odoacer deposed the last western emperor, Romulus Augustulus, and the western Roman Empire came to an end.
The eastern Roman Empire, with its capital at Constantinople, survived for almost another thousand years. Today we call it the Byzantine Empire, after the ancient name of Constantinople. The Byzantine Empire fell to the Ottoman Turks in 1453.
The Legacy of the Roman Empire
The Roman Empire’s legacy is the foundation of Western civilization. Roman law became the legal system of continental Europe and the basis of civil law traditions throughout the world. Latin became the parent of the Romance languages (Italian, French, Spanish, Portuguese, Romanian) and the official language of the Roman Catholic Church. Roman roads and aqueducts, many of which are still in use, provided the infrastructure of the medieval world. Roman ideas of citizenship, law, and the imperial state were taken up by the Holy Roman Empire, the Byzantine Empire, the Habsburgs, the Russian tsars, the Napoleonic Empire, and the modern nation-state. The very idea of Europe as a cultural and political entity is, in large part, a Roman inheritance.