Battle of Philippi was the final battle in the Wars of the Second Triumvirate between the forces of Mark Antony and Octavian ( of the Second Triumvirate ) and the leaders of Julius Caesar 's assassination , Marcus Junius Brutus and Gaius Cassius Longinus in 42 BC , at Philippi in Macedonia . The Second Triumvirate declared this civil war ostensibly to avenge Julius Caesar 's assassination in 44 BC , but the underlying cause was a long-brewing conflict between the so-called Optimates and the so-called Populares
Julius Caesar 's assassination
Assassination of Julius Caesar
Battle of Philippi