The Battle of Pharsalus was the decisive battle of Caesar's Civil War, fought on 9 August 48 BC between the rival Roman armies of Julius Caesar and Pompey at Pharsalus in central Greece. Caesar deployed a fourth line of battle rather than the usual three, enabling his force to drive off a flanking cavalry attack. The fourth line then carried out a flanking action of its own, combined with a renewed frontal attack. Pompey's infantry fled.