Roman Empire
During the classical period, the Roman Empire controlled the Mediterranean and much of Europe, Western Asia, and North Africa. The Romans conquered most of these territories in the time of the Republic, and it was ruled by emperors following Octavian's assumption of power in 27 BC. Over the 4th century AD, the empire split into western and eastern halves. The Western Empire collapsed in 476 AD, while the Eastern Empire endured until the fall of Constantinople in 1453.
By 100 BC, the city of Rome had expanded its rule from the Italian peninsula to most of the Mediterranean and beyond. However, it was severely destabilised by civil wars and political conflicts, which culminated in the victory of Octavian over Mark Antony and Cleopatra at the Battle of Actium in 31 BC, and the subsequent conquest of the Ptolemaic Kingdom in Egypt. In 27 BC, the Roman Senate granted Octavian overarching military power and the new title of Augustus, marking his accession as the first Roman emperor. The vast Roman territories were organized into senatorial provinces, governed by proconsuls who were appointed by lot annually, and imperial provinces, which belonged to the emperor but were governed by legates.
The first two centuries of the Empire saw a period of unprecedented stability and prosperity known as the Pax Romana. Rome reached its greatest territorial extent under Trajan, but a period of increasing trouble and decline began under Commodus. In the 3rd century, the Empire underwent a 49-year crisis that threatened its existence due to civil war, plagues and barbarian invasions. The Gallic and Palmyrene empires broke away from the state and a series of short-lived emperors led the Empire, which was later reunified under Aurelian. The civil wars ended with the victory of Diocletian, who set up two different imperial courts in the Greek East and Latin West. Constantine the Great, the first Christian emperor, moved the imperial seat from Rome to Byzantium in 330, and renamed it Constantinople. The Migration Period, involving large invasions by Germanic peoples and by the Huns of Attila, led to the decline of the Western Roman Empire. With the fall of Ravenna to the Germanic Herulians and the deposition of Romulus Augustus in 476 by Odoacer, the Western Empire finally collapsed. The Byzantine Empire survived for another millennium with Constantinople as its sole capital, until the city's fall in 1453.
Due to the Empire's extent and endurance, its institutions and culture had a lasting influence on the development of language, religion, art, architecture, literature, philosophy, law, and forms of government across its territories. Latin evolved into the Romance languages while Medieval Greek became the language of the East. The Empire's adoption of Christianity resulted in the formation of medieval Christendom. Roman and Greek art had a profound impact on the Italian Renaissance. Rome's architectural tradition served as the basis for Romanesque, Renaissance, and Neoclassical architecture, influencing Islamic architecture. The rediscovery of classical science and technology in medieval Europe contributed to the Scientific Renaissance and Scientific Revolution. Many modern legal systems, such as the Napoleonic Code, descend from Roman law. Rome's republican institutions have influenced the Italian city-state republics of the medieval period, the early United States, and modern democratic republics.
History
Transition from Republic to Empire
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 and provinces administered by military commanders. It was governed by annually elected magistrates in conjunction with the Senate. The 1st century BC was a time of political and military upheaval, which ultimately led to rule by emperors. The consuls' military power rested in the Roman legal concept of imperium, meaning "command". Occasionally, successful consuls or generals were given the honorary title imperator ; this is the origin of the word emperor, since this title was always bestowed to the early emperors.Rome suffered a long series of internal conflicts, conspiracies, and civil wars from the late second century BC 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 and made him princeps 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. 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.
''Pax Romana''
The 200 years that began with Augustus's rule are traditionally regarded as the Pax Romana. 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". 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.Among the so-called "Five Good Emperors", Hadrian is particularly noted for consolidating the empire's frontiers and embarking on ambitious building projects throughout the provinces. 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 and the Capitoline Triad. 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. Later tradition and archaeological evidence also indicate a Temple of Venus near the site of the Holy Sepulchre.
Hadrian's measures, combined with restrictions on Jewish practices, helped spark the Bar Kokhba Revolt. 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. Most scholars consider Hadrianic Aelia to have been unwalled, with free-standing gate complexes rather than a continuous defensive circuit.
Transition from classical to late antiquity
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", a comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the Empire's decline.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. In defining historical epochs, this crisis sometimes marks the transition from classical to late antiquity. Aurelian stabilised the empire militarily and Diocletian reorganised and restored much of it in 285. Diocletian's reign brought the empire's most concerted effort against the perceived threat of Christianity, the "Great Persecution".
Diocletian divided the empire into four regions, each ruled by a separate tetrarch. 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.
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, but the empire had assimilated so many Germanic peoples of dubious loyalty to Rome that the empire started to dismember itself. Most chronologies place the end of the Western Roman Empire in 476, when Romulus Augustulus was forced to abdicate to the Germanic warlord Odoacer.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. 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. His claim was soon recognized by the Patriarchate of Constantinople, but not by European monarchs.