The Battle of Pharsalus was the decisive battle of Caesar's Civil War fought on 9 August 48 BC near Pharsalus in Central Greece. Julius Caesar and his allies formed up opposite the army of the Roman Republic under the command of Pompey. Pompey had the backing of a majority of Roman senators and his army significantly outnumbered the veteran Caesarian legions.

Caesar's civil war was a civil war during the late Roman Republic between two factions led by Gaius Julius Caesar and Gnaeus Pompeius Magnus (Pompey), respectively. The main cause of the war was political tensions relating to Caesar's place in the republic on his expected return to Rome on the expiration of his governorship in Gaul.