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Transition from Republic to Empire

Augustus of Prima Porta
Rome had begun expanding shortly after the founding of the Roman Republic in the 6th century BC, though not outside the Italian Peninsula until the 3rd century BC. The Republic was not a nation-state in the modern sense, but a network of self-ruled towns (with varying degrees of independence from the Senate) and provinces administered by military commanders. It was governed by annually elected magistrates (Roman consuls above all) in conjunction with the Senate.[22] The 1st century BC was a time of political and military upheaval, which ultimately led to rule by emperors.[23][24][25] The consuls' military power rested in the Roman legal concept of imperium, meaning "command" (typically in a military sense).[26] Occasionally, successful consuls or generals were given the honorary title imperator (commander); this is the origin of the word emperor, since this title was always bestowed to the early emperors.[27][g]

Rome suffered a long series of internal conflicts, conspiracies, and civil wars from the late second century BC (see Crisis of the Roman Republic) while greatly extending its power beyond Italy. In 44 BC Julius Caesar was briefly perpetual dictator before being assassinated by a faction that opposed his concentration of power. This faction was driven from Rome and defeated at the Battle of Philippi in 42 BC by Mark Antony and Caesar's adopted son Octavian. Antony and Octavian divided the Roman world between them, but this did not last long. Octavian's forces defeated those of Mark Antony and Cleopatra at the Battle of Actium in 31 BC. In 27 BC the Senate gave him the title Augustus ("venerated") and made him princeps ("foremost") with proconsular imperium, thus beginning the Principate, the first epoch of Roman imperial history. Although the republic stood in name, Augustus had all meaningful authority.[29] During his 40-year rule, a new constitutional order emerged so that, upon his death, Tiberius would succeed him as the new de facto monarch.[30]

Pax Romana
Main article: Pax Romana
The so-called "Five Good Emperors" of 96–180 AD

Nerva (r. 96–98)

Trajan (r. 98–117)

Hadrian (r. 117–138)

Antoninus Pius (r. 138–161)

Marcus Aurelius (r. 161–180)
The 200 years that began with Augustus's rule are traditionally regarded as the Pax Romana ("Roman Peace"). The cohesion of the empire was furthered by a degree of social stability and economic prosperity that Rome had never before experienced. Uprisings in the provinces were infrequent and put down "mercilessly and swiftly".[31] The success of Augustus in establishing principles of dynastic succession was limited by his outliving a number of talented potential heirs. The Julio-Claudian dynasty lasted for four more emperors—Tiberius, Caligula, Claudius, and Nero—before it yielded in 69 AD to the strife-torn Year of the Four Emperors, from which Vespasian emerged as the victor. Vespasian became the founder of the brief Flavian dynasty, followed by the Nerva–Antonine dynasty which produced the "Five Good Emperors": Nerva, Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius.[32]

Among the so-called “Five Good Emperors,” Hadrian (r. 117–138) is particularly noted for consolidating the empire’s frontiers and embarking on ambitious building projects throughout the provinces.[33] In Judaea, which had long been the center of Jewish national and religious life, his reign marked a decisive turning point. After earlier Jewish resistance to Roman rule, Hadrian visited the region in 129/130 CE and refounded Jerusalem as the Roman colony Aelia Capitolina, naming it after his family (Aelius) and the Capitoline Triad.[34] The refoundation overlaid the destroyed Jewish city with a new Roman urban plan, and included the construction of a Temple to Jupiter on the site of the former Jewish Temple.[35] Later tradition and archaeological evidence also indicate a Temple of Venus near the site of the Holy Sepulchre.[36]

Hadrian’s measures, combined with restrictions on Jewish practices, helped spark the Bar Kokhba Revolt (132–135 CE). After crushing the uprising, Roman forces expelled most Jews from Jerusalem, barring their entry except on certain days, and rebuilt the city as a statement of imperial power and domination.[33] Most scholars consider Hadrianic Aelia to have been unwalled, with free-standing gate complexes (such as the northern gate beneath today’s Damascus Gate) rather than a continuous defensive circuit.[37]

Transition from classical to late antiquity
Main articles: Later Roman Empire and Fall of the Western Roman Empire
See also: Barbarian kingdoms and Byzantine Empire

The Barbarian invasions consisted of the movement of (mainly) ancient Germanic peoples into Roman territory. Historically, this event marked the transition between classical antiquity and the Middle Ages.
In the view of contemporary Greek historian Cassius Dio, the accession of Commodus in 180 marked the descent "from a kingdom of gold to one of rust and iron",[38] a comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the Empire's decline.[39][40]

In 212, during the reign of Caracalla, Roman citizenship was granted to all freeborn inhabitants of the empire. The Severan dynasty was tumultuous; an emperor's reign was ended routinely by his murder or execution and, following its collapse, the Empire was engulfed by the Crisis of the Third Century, a period of invasions, civil strife, economic disorder, and plague.[41] In defining historical epochs, this crisis sometimes marks the transition from Classical to Late Antiquity. Aurelian (r. 270–275) stabilised the empire militarily and Diocletian reorganised and restored much of it in 285.[42] Diocletian's reign brought the empire's most concerted effort against the perceived threat of Christianity, the "Great Persecution".[43]

Diocletian divided the empire into four regions, each ruled by a separate tetrarch.[44] Confident that he fixed the disorder plaguing Rome, he abdicated along with his co-emperor, but the Tetrarchy collapsed shortly after. Order was eventually restored by Constantine the Great, who became the first emperor to convert to Christianity, and who established Constantinople as the new capital of the Eastern Empire. During the decades of the Constantinian and Valentinian dynasties, the empire was divided along an east–west axis, with dual power centres in Constantinople and Rome. Julian, who under the influence of his adviser Mardonius attempted to restore Classical Roman and Hellenistic religion, only briefly interrupted the succession of Christian emperors. Theodosius I, the last emperor to rule over both East and West, died in 395 after making Christianity the state religion.[45]


The Roman Empire by 476, noting western and eastern divisions

The administrative divisions of the Roman Empire in 395 AD
Fall in the West and survival in the East
The Western Roman Empire began to disintegrate in the early 5th century. The Romans fought off all invaders, most famously Attila,[46] but the empire had assimilated so many Germanic peoples of dubious loyalty to Rome that the empire started to dismember itself.[47] Most chronologies place the end of the Western Roman Empire in 476, when Romulus Augustulus was forced to abdicate to the Germanic warlord Odoacer.[48][49][50]

Odoacer ended the Western Empire by declaring Zeno sole emperor and placing himself as Zeno's nominal subordinate. In reality, Italy was ruled by Odoacer alone.[48][49][51] The Eastern Roman Empire, called the Byzantine Empire by later historians, continued until the reign of Constantine XI Palaiologos, the last Roman emperor. He died in battle in 1453 against Mehmed II and his Ottoman forces during the siege of Constantinople. Mehmed II adopted the title of caesar in an attempt to claim a connection to the former Empire.[52][53] His claim was soon recognized by the Patriarchate of Constantinople, but not by European monarchs.