In Antony and Cleopatra, what sea battle is fought between Octavius and Antony?

In Antony and Cleopatra, the sea battle fought between Octavius and Antony is the Battle of Actium.

Shakespeare’s play draws on the historical conflict between Octavian—later known as Augustus—and Mark Antony. The Battle of Actium took place on September 2, 31 BC, in the Ionian Sea off the western coast of Greece, near the promontory of Actium. Octavian’s fleet, commanded operationally by Marcus Agrippa, defeated the combined forces of Antony and Cleopatra.

The battle was a decisive turning point in Roman history. Cleopatra’s fleet broke through the Roman line, and Antony followed her rather than remaining with his main force. Their defeat eventually led to Octavian’s conquest of Egypt and the deaths of Antony and Cleopatra in 30 BC. Octavian’s victory left him the dominant power in Rome and helped mark the transition from Roman Republic to Roman Empire.

A common mix-up is the Battle of Pharsalus, which was fought between Julius Caesar and Pompey in 48 BC. The Battle of Philippi, another Roman civil-war battle, involved Octavian and Antony fighting Brutus and Cassius—not each other.