despite the Republic's traditional and lawful constraints against any individual's acquisition of permanent political powers, Roman politics was dominated by a small number of Roman leaders, their uneasy alliances punctuated by a series of civil wars.
The victor in one of these civil wars, Octavian, reformed the Republic as a Principate, with himself as Rome's "first citizen" (princeps). The Senate continued to sit and debate. Annual magistrates were elected as before, but final decisions on matters of policy, warfare, diplomacy and appointments were privileged to the princeps as "first among equals" later to be known as imperator due to the holding of imperium, from which the term emperor is derived. His powers were monarchic in all but name, and he held them for his lifetime, on behalf of the Senate and people of Rome. The Roman Republic was never restored, but neither was it abolished, so the exact date of the transition to the Roman Empire is a matter of interpretation. Historians have variously proposed the appointment of Julius Caesar as perpetual dictator in 44 BC, the defeat of Mark Antony at the Battle of Actium in 31 BC, and the Roman Senate's grant of extraordinary powers to under the first settlement and Octavian adopting the moniker Augustus in 27 BC, as the defining event ending the Republic.
