when octavian heard that brutus was on his way to rome, he made peace with antony. their armies, which together totaled about 19 legions, marched to meet brutus and cassius. the two sides met in two engagements known as the battle of philippi. the first was fought on 3 october 42 bc, in which brutus defeated octavian's forces. cassius was defeated by antony, and committed suicide, because he thought brutus had also failed.