Who won the Battle of Pharsalus?
Julius Caesar won the Battle of Pharsalus on 9 August 48 BC. Though outnumbered nearly two to one by Pompey the Great, Caesar used a hidden fourth line of infantry to smash Pompey's cavalry charge, then routed his whole army. The victory decided Rome's civil war and left Caesar master of the Roman world.4
In the summer of 48 BC the two greatest Romans of the age met in battle on a plain in Greece. Pompey the Great had the Senate, the larger army and the cavalry; Julius Caesar had his hardened veterans and nerve. In a single morning Caesar broke him, and with him the Roman Republic.5
The road to civil war
When the Senate, backed by Pompey, ordered Caesar to give up his command, Caesar crossed the Rubicon in January 49 BC and plunged Rome into civil war. The towns of Italy did not rise against him as the Senate had expected, and Pompey, with the consuls and most of the Senate, led his two legions to Brundisium and across the Adriatic to Epirus to raise a great army from Rome's eastern provinces. Caesar turned first on the Pompeian legions in Spain, crushed them at Ilerda, and came back to Rome as dictator.6 › Battle of Alesia, 52 BC
The two men had once been partners: Pompey had been Caesar's fellow triumvir. By 49 BC that partnership was over, and Pompey had become the firm defender of the Senate and of the Republic against the conqueror of Gaul.7
Dyrrhachium and the march into Thessaly
In the East, Pompey and the loyalist senators gathered nine legions and a fleet that ruled the sea. Caesar surprised them by crossing the Adriatic in January 48 BC with seven legions, well before the sailing season, and was later joined by Mark Antony with four more. He tried to blockade Pompey's much larger army near Dyrrhachium on the Adriatic coast, in today's Albania, for months, but Pompey broke the siege lines and inflicted a sharp defeat on him.8
Caesar slipped away by night and marched east over the Pindus mountains into Thessaly, where a fertile plain could feed his men. Pompey followed, pressed by senators in his camp who wanted a quick end to a war that had already lasted a year and a half. Caesar's own account says Pompey's officers swore not to return to camp except as victors, and that his cavalry commander Titus Labienus scorned the army facing them.9
The armies at Pharsalus
Pompey camped on the high ground near Pharsalus, in today's Farsala, and for several days would not come down. Exactly where the armies stood is still debated: the traditional site lies south of the Enipeus River near Pharsalus itself, while a newer theory, Britannica notes, places Pompey's camp north of the river near Old Pharsalus, which would make it the battle of Palaepharsalus. Each morning Caesar offered battle on the plain. He was about to break camp and march elsewhere when Pompey's army moved down onto the level ground.10
Pompey's army was far larger. Caesar, who counted carefully, gives him 110 cohorts, about 45,000 men, plus some 2,000 recalled veterans, and Plutarch repeats the figure of 45,000 foot; Britannica gives 47,000 legionaries. Pompey also had nearly 7,000 cavalry under Labienus, with archers and slingers, against Caesar's 1,000 horse. Caesar had 80 cohorts, about 22,000 men, almost all veterans, many of them from the Gallic wars.11
The plan was plain to read. Pompey anchored his right on the Enipeus and massed all his cavalry on his left, to sweep around Caesar's open right flank and roll up his line from behind. Caesar put Mark Antony on his left, Domitius Calvinus in the center, and himself on the right with the Tenth Legion; in his own account the right wing was commanded by Publius Sulla, with Caesar facing Pompey. Seeing the mass of horse opposite, he quietly pulled six cohorts out of his third line to form a hidden fourth line behind his own cavalry, told them that the day would depend on their courage, and ordered the third line not to move without his signal.12
Caesar's hidden fourth line
Pompey ordered his infantry to stand still and receive the charge, hoping that Caesar's men would tire themselves running across the plain. Caesar thought this a mistake, since it robbed his own soldiers of the fire of attack. His veterans saw that the enemy was not coming, halted on their own halfway to catch their breath, then charged, threw their javelins and closed with swords. A veteran centurion named Crastinus led the charge with about 120 volunteers, promising Caesar that he would earn his thanks alive or dead. He was killed in the fighting.13
When Pompey's great cavalry charge came, it drove Caesar's horsemen back as expected, and Labienus began to spread his squadrons out to envelop the flank. Then Caesar's hidden fourth line rushed out and struck them head-on. Plutarch says Caesar had told the cohorts not to throw their javelins but to thrust them at the riders' faces, reckoning that young aristocrats proud of their looks would not stand it. The charge broke and fled for the hills. The cohorts cut down the exposed archers and slingers and swung into the flank of Pompey's infantry, while Caesar sent his fresh third line into the front.14
The rout of Pompey
With his cavalry gone and his flank turned, Pompey's huge army collapsed. Plutarch has Pompey sitting silent in his tent until the enemy reached the rampart, then changing into plain clothes and slipping away. Caesar's men stormed the camp, where the signs of luxury showed how sure of victory the Pompeians had been. The fugitives took refuge on a hill; Caesar cut them off with four legions, and without water they surrendered and were spared.15
Caesar reported that he lost no more than 200 men from the ranks and about 30 centurions, and that about 15,000 of the enemy fell and more than 24,000 surrendered, with 180 standards and nine eagles taken. Britannica treats Caesar's own losses as improbably low. Plutarch cites the historian Asinius Pollio for no more than 6,000 Pompeian soldiers killed. Walking over the field, Caesar is said to have groaned, "They would have it so," blaming his enemies for forcing the war on him. Plutarch adds that Caesar was delighted when Marcus Brutus was brought in unharmed; four years later Brutus would be among his killers.16
Pompey's end
Pompey fled by way of Amphipolis, Mytilene and Cyprus to Egypt, hoping that the young king Ptolemy XIII, then at war with his sister Cleopatra, would shelter him. The king's advisers decided otherwise. At Pelusium the officers Achillas and Septimius invited Pompey into a small boat to bring him ashore and killed him. When Caesar reached Alexandria soon after, he was offered Pompey's head; Plutarch says he turned away from it but took Pompey's seal ring and wept over it, and Britannica notes that he is said to have mourned his old friend.17
Why Pharsalus mattered
Pharsalus decided the civil war in Caesar's favor. The Pompeian cause fought on for three more years, in Africa at Thapsus in 46 BC and in Spain at Munda in 45 BC, but it never again had an army like the one lost in Thessaly. Caesar pardoned his surviving enemies, returned to Rome as dictator and was murdered a year after Munda, in 44 BC.18 › Battle of Philippi, 42 BC
Pharsalus is studied as a masterclass in how a smaller, better-led army can beat a larger one by anticipating the enemy's plan. Pompey's battle plan was sound on paper; Caesar simply read it in time and placed six cohorts where it would fail. See how Caesar's generalship compares in Alexander vs Caesar. The rivalry that led both men to this plain is traced in Pompey vs Caesar.19
A note on the date
Caesar's victory is dated to 9 August 48 BC, but that is a date in the old Roman republican calendar, which had drifted badly. Britannica notes that by the 40s BC the civic calendar ran about three months ahead of the solar year, which is why Caesar himself reformed it in 46 BC, creating the Julian calendar. The battle was therefore fought earlier in the summer than the date suggests. The plain lies near the modern town of Farsala in Thessaly, central Greece.20
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