Octavianus (later Emperor Augustus) raised XV "Apollinaris" in order to end the occupation of Sicily by Sextus Pompeius, who was threatening Rome's grain supply. After the Battle of Actium, where the legion probably gained its epitaph "Apollinaris", it was sent to garrison Illyricum, where it probably remained until 6 BC, though it might have seen action in the Cantabrian Wars.