What happened at the battle of Actium?

Answer 1

Actium, 31BC - Octavian defeated Mark Antony. After the assassination of Julius Caesar, they both allied to take revenge (Philippi, 42BC), but later on they opposed, especially, when Antony fell in love with Cleopatra (VII), and had sons with her. Rome was afraid that an Egyptian heir jeopardized their throne. In 27BC, Octavian became the first emperor (he did not use this title - he used princeps) of Rome and the Senate named him Augustus.

Answer 2

The Battle of Actium was the war that de facto ended the Roman Republic. Octavian won the battle in 31 BC, and was declared the first Roman Imperator (or Emperor) four years later in 27 BC.