Emperors of Roman 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. Thus, it was an "empire" (a great power) long before it had an emperor.[21] 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" (t 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]

As Roman provinces were being established throughout the Mediterranean, Italy maintained a special status which made it domina provinciarum ("ruler of the provinces"),[31