Battle of Pharsalus

On 9 August 48 BC, by the Roman calendar of the time, Julius Caesar met the army of his rival Pompey on the plain of Thessaly in central Greece, near the town of Pharsalus. Although heavily outnumbered, especially in cavalry, Caesar's veterans won a crushing victory. Pompey fled to Egypt, where he was murdered, and the battle made Caesar the dominant figure in the Roman world, though fighting with Pompey's supporters went on for several more years.

When civil war broke out, Caesar quickly took Rome, drove Pompey and most of the Senate out of Italy, and defeated Pompey's commanders in Spain. In 48 BC he crossed the Adriatic and tried to besiege Pompey at Dyrrachium, but was beaten there and withdrew east into Thessaly. Pompey followed. He would have preferred to wear Caesar down without risking a battle, but many of the senators in his camp were impatient and accused him of dragging out the war to prolong his own command.

Ancient writers mainly counted Roman legionaries and paid less attention to allied troops, so totals are uncertain. Caesar says he had 22,000 legionaries in eight under-strength legions, mostly veterans of his Gallic campaigns, plus 1,000 cavalry and a few thousand Greek light troops. Caesar, Appian and Plutarch give Pompey 45,000 legionaries; modern historians suggest perhaps 36,000 to 38,000. Pompey's real advantage lay in his 5,000 to 7,000 cavalry and thousands of archers and slingers, many supplied by client kings from the eastern provinces.

Both armies formed the usual three lines, with one flank resting on the Enipeus river. Pompey massed almost all his cavalry and light troops on his left under Titus Labienus, planning to sweep around Caesar's right and into his rear while his deep infantry formation held the centre. Caesar, thinning his own line to match Pompey's front, saw the danger. He took cohorts from his third line to form a hidden fourth line behind his right wing, with orders to wait for the cavalry attack.

Pompey ordered his infantry to stand and receive the charge, hoping Caesar's men would arrive tired and disordered after crossing the open ground. Caesar's veterans halted to recover their breath before closing, then engaged the Pompeian centre. On the left of Pompey's line, Labienus's horsemen drove back Caesar's small cavalry force, only to run into the fourth line, whose soldiers used their javelins as thrusting spears against the riders. The Pompeian cavalry panicked and fled for the hills, exposing the flank of their infantry. Caesar then sent in his reserves, and Pompey's left wing broke.

Seeing his army giving way, Pompey withdrew to his camp and then escaped in disguise. Caesar's men stormed the camp, which was defended for a while by Thracian and other auxiliaries.

Figures for the losses are disputed. Caesar claimed to have lost only about 200 men and 30 centurions while killing many thousands of the enemy; these figures are widely thought exaggerated. Appian puts Caesar's losses at up to 1,200 and Pompey's at 6,000, and many thousands of Pompeians were captured.

Caesar announced that he would pardon those who asked for mercy, and many did, among them Marcus Junius Brutus. Others, including Cato, regrouped and carried on the fight from Libya. Pompey sailed by way of Mytilene and Cilicia to Egypt, hoping for help from King Ptolemy XIII, but was killed on arrival on the king's orders. Caesar, following him, reached Alexandria on 2 October 48 BC and became entangled in the dynastic quarrel between Ptolemy and Cleopatra.

The battle did not end the civil war, but it shifted loyalties across the eastern provinces, which had largely backed Pompey, and gave Caesar the authority that would make him master of Rome until his assassination. Many historians see it as a decisive step in the end of the Roman Republic.

Our 100 BCE map shows the Roman Republic before the civil wars, and our 1 BCE map shows the Roman Empire that emerged from them. The battlefield lies in modern Greece.