The Battle of Actium was also an important turning point in the history of the relationship between Egypt and Rome. When Octavian (later known as the Emperor Augustus) met the combined forces of Mark Antony and Queen Cleopatra of Egypt, Roman forces faced Roman forces, pretty evenly matched. The fighting continued throughout the day of September 2, 31 B.C., until, inexplicably, Cleopatra took her troops and left the naval battle. Mark Antony, leaving his troops behind, followed her. The result was that Octavian, helped by Marcus Vipsanius Agrippa, won the battle.
Since Marcus Aemilius Lepidus, part of the second triumvirate -- with Antony and Octavian, had already been exiled, this left only Octavian to be the leader of Rome, He would soon become Augustus, the princeps, and first Roman emperor. [See Pennell's History of Rome.]