 SPOILER: The Battle of Philippi was actually 2 separate encounters  spread over 3 weeks. The first, on October 3, 42 BC, began with a  surprise flank attack by Antony, featured the capture of Octavians  headquarters by Brutus and much higher losses on the part of the  Triumvirs, but resulted in Cassius committing suicide in the  mistaken belief that the Republicans were defeated and he was about  to be captured. The second, on October 23, resulted in the decisive  defeat of Brutus, after which he committed suicide.