What was the name of the sea battle in which the forces of Octavian defeated those of Cleopatra and Mark Antony?

The Battle of Actium was the decisive confrontation of the Final War of the Roman Republic, a naval engagement between Octavian and the combined forces of Mark Antony and Cleopatra. The battle occurred in September 31 BC, on the Ionian Sea near the promontory of Actium, in the Roman province of Epirus Vetus in Greece.

Antony, with 500 ships and 70,000 infantry, made his camp at Actium, which was on the southern side of a strait leading from the Ionian Sea into the Ambracian Gulf. Octavian, with 400 ships and 80,000 infantry, arrived from the north and, by occupying Patrae and Corinth, managed to block Antony’s southward connections with Egypt via the Peloponnese.

In the end, Antony either hoped to win at sea because he was outmaneuvered on land or he simply needed to break the land blockade. Nonetheless, Antony took Cleopatra’s advice about the fleet. He placed his ships outside the bay; Cleopatra’s ships were behind his.

The ensuing naval battle was hotly contested, with each side’s squadrons trying to outflank the other. The battle lasted until Cleopatra took her Egyptian galleys and fled. Antony then broke off fighting and with a few ships managed to follow her. The remainder of his fleet became disheartened and surrendered to Octavian. About a week later, Antony’s land forces surrendered.

The Battle of Actium gave Octavian (emperor Augustus after 27 BC), a decisive victory over Mark Antony. Octavian then became the undisputed master of the Roman world.