Military operations began in 31 BC, when Octavian's general Agrippa captured Methone, a Greek town allied to Antony.
Several dates are commonly proposed to mark the transition from Republic to Empire, including the date of Julius Caesar's appointment as perpetual roman dictator (44 BC), the victory of Caesar's heir Octavian at the Battle of Actium (September 2, 31 BC), and the Roman Senate's granting to Octavian the honorific Augustus.
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At this juncture, the Roman empire was convulsed by its first major civil war since the Battle of Actium exactly a century earlier: the Year of the Four Emperors (69-70 AD).
After Cato the Younger was defeated by Caesar, he committed suicide (46 BC) in Utica, and Numidia became briefly the province of Africa Nova until Augustus restored Juba II (son of Juba I) after the Battle of Actium.