For the American Civil War battle, see Battle of Philippi Races.

The Battle of Philippi was the final battle in the Wars of the Second Triumvirate between the forces of Mark Antony and Octavian (the Second Triumvirate) against the forces of Julius Caesar's assassins Marcus Junius Brutus and Gaius Cassius Longinus in 42 BC, at Philippi in Macedonia.

The battle consisted of two engagements in the plain West of the ancient city of Philippi. The first occurred on the first week of October; Brutus faced Octavian, while Antony's forces were up against those of Cassius. At first, Brutus pushed back Octavian and entered his legions' camp. But to the south, Antony defeated Cassius, and Cassius, hearing a false report of Brutus' failure, committed suicide. Both armies retreated to their camps with their spoils, and the battle was essentially a draw, but for Cassius' suicide. A second encounter, on 23 October, finished off Brutus' forces, and he committed suicide in turn, leaving the triumvirate in control of the Roman world.