(31 BC) Naval battle off Acarnania , Greece, between Octavian (later Augustus ) and Mark Antony .
With 500 ships and 70,000 infantry, Antony camped at Actium, between the Ionian Sea and the Ambracian Gulf. Octavian, with 400 ships and 80,000 infantry, cut Antony's line of communication from the north. Desertion by allies and a lack of supplies forced Antony to act. Outmaneuvered on land, he followed Cleopatra 's advice to attack Octavian at sea. Antony's larger fleet included his own and Cleopatra's ships. In the heat of battle Cleopatra fled with her galleys, and Antony followed with a few ships. His fleet surrendered immediately, his army a week later. Octavian's victory left him undisputed ruler of the Roman world.