Battle of Pharsalus (48 BC): Caesar Defeats Pompey the Great

The Battle of Pharsalus was fought on 9 August 48 BC in Thessaly, central Greece, between Julius Caesar and Pompey the Great. Caesar’s smaller but battle-hardened army defeated Pompey’s forces, which represented the Roman Senate. The battle decided the main phase of Caesar’s civil war, and Pompey’s flight to Egypt ended with his murder there a few weeks later.

Background: from the Rubicon to Greece

The civil war began when Caesar crossed the Rubicon into Italy in January 49 BC. Pompey and most of the Senate abandoned Rome and in March sailed to Greece, where Pompey could draw on the wealth, fleets and client kings of the eastern provinces.

While Pompey gathered a large army in Macedonia, Caesar defeated Pompey’s generals in Spain. In January 48 BC he crossed the Adriatic with part of his army, slipping past Pompey’s fleet, and Mark Antony followed with reinforcements in the spring.

Dyrrachium and the march into Thessaly

The two armies first met near Dyrrachium (modern Durrës in Albania), Pompey’s main supply base. Caesar tried to besiege Pompey’s larger army with a long line of fortifications. In July 48 BC Pompey broke through the lines and inflicted a serious defeat; Caesar said he lost about 1,000 men.

Caesar withdrew inland to Thessaly, where his hungry troops could find grain. Pompey followed, joined by his father-in-law Quintus Caecilius Metellus Scipio, who brought legions from Syria. Many senators in Pompey’s camp were confident of victory and pressed him to fight rather than wear Caesar down by starving him of supplies, which had been Pompey’s preferred strategy.

The armies

Caesar’s own account gives the strength of the two sides. Pompey had 110 cohorts, about 45,000 legionaries, and some 7,000 cavalry, together with archers and slingers. Caesar had 80 cohorts, about 22,000 men, and around 1,000 cavalry. Caesar had reason to stress the odds against him, and modern historians treat his figures with some caution, but Pompey’s advantage, especially in cavalry, was real.

Pompey anchored his right wing on the river Enipeus and massed nearly all his cavalry on his left, under Titus Labienus, Caesar’s former second-in-command in Gaul. His plan was simple: the cavalry would sweep around Caesar’s right flank and attack his legions from behind.

Caesar placed Mark Antony in command of his left, Gnaeus Domitius Calvinus in the centre and Publius Sulla on the right, and stationed himself on the right with his favourite Tenth Legion. Seeing Pompey’s cavalry, he took one cohort from the third line of each legion to form a fourth line, six cohorts in all, hidden behind his right wing.

The battle

Pompey ordered his infantry to stand still and receive Caesar’s attack, hoping that Caesar’s men would tire themselves by running twice the normal distance. Caesar later criticised this, saying that the charge gave soldiers energy and spirit. His experienced troops noticed that the enemy was not advancing, halted to catch their breath halfway, and then charged.

As the infantry lines clashed, Labienus launched the cavalry attack on Caesar’s right. Caesar’s small cavalry force gave way. Then the fourth line advanced. According to Plutarch, the soldiers were told to thrust their javelins upwards at the faces of the horsemen rather than throw them. The cavalry, many of them young and inexperienced, broke and fled to the hills, leaving the archers and slingers behind them to be cut down.

The six cohorts then wheeled round and attacked the exposed left flank of Pompey’s infantry. At the same moment Caesar committed his fresh third line. Pompey’s army began to collapse. Pompey himself rode back to his camp, and when Caesar’s men stormed it he fled in disguise.

Caesar records that his troops found the Pompeian camp prepared for a victory feast, with tents decorated and tables laid with silver. He pursued the remnants of the Pompeian infantry, who surrendered the next morning on a hill where they had no water.

Losses and pardons

Caesar claimed to have lost only about 200 soldiers and 30 centurions, while about 15,000 of the enemy were killed and some 24,000 surrendered. The historian Gaius Asinius Pollio, who fought on Caesar’s side, gave a lower figure of about 6,000 Pompeian dead, according to Plutarch. Most modern historians consider Pollio’s figure more realistic.

Among the dead was Lucius Domitius Ahenobarbus, whom Caesar had pardoned once before. Caesar again showed clemency to most of the captured Romans. Among those pardoned was Marcus Junius Brutus, who would later help to assassinate him. Labienus, Metellus Scipio, Cato and other leaders escaped to continue the war.

Pompey’s flight and death

Pompey reached the coast and sailed to Mytilene on Lesbos, where he collected his wife Cornelia, and then towards Egypt. He hoped for support from the young king Ptolemy XIII, whose father he had helped to restore to the throne.

The king’s advisers, the eunuch Pothinus, the general Achillas and the tutor Theodotus, decided that the safest course was to kill him and win Caesar’s favour. On 28 September 48 BC, as Pompey was taken ashore by boat near Pelusium, he was stabbed to death by Achillas and a former Roman officer, Lucius Septimius, in sight of his wife on the ship. He was about 57 years old.

When Caesar arrived in Alexandria a few days later he was shown Pompey’s head and is said to have wept. His stay in Egypt drew him into the Alexandrian War and his alliance with Cleopatra VII.

Legacy and memory

Pharsalus quickly became a symbol of the Republic’s fall. Suetonius, quoting Asinius Pollio, reports that Caesar looked over the dead Romans on the battlefield and said in effect that his enemies had wanted this, since he would have been condemned despite all his achievements had he not turned to his army. Whether or not the words are exact, they show how Caesar justified the war: as self-defence against opponents who refused any compromise.

A century later the poet Lucan, writing under the emperor Nero, made the battle the centre of his epic on the civil war, often called the Pharsalia. For Lucan, Pharsalus was the day when Roman liberty died, and Pompey and Cato were tragic defenders of a lost cause. His poem shaped how later readers, from medieval scholars to Renaissance painters, imagined the battle.

Military historians remember Pharsalus as a classic example of a smaller, well-led and experienced army defeating a larger force. Caesar’s use of a hidden reserve line to meet a predictable cavalry attack, and his decision to commit his third line at the decisive moment, are still studied as models of tactical judgement.

The exact battlefield has never been located with certainty. Scholars have argued for sites on both the north and south banks of the Enipeus near Farsala, and no excavations have produced conclusive remains.

Timeline

• 49 BC, January: Caesar crosses the Rubicon; the civil war begins.
• 49 BC, March: Pompey and the Senate leave Italy for Greece.
• 48 BC, January: Caesar lands in Epirus with part of his army.
• 48 BC, July: Pompey breaks Caesar’s siege lines at Dyrrachium.
• 48 BC, 9 August: Caesar defeats Pompey at Pharsalus.
• 48 BC, 28 September: Pompey is murdered near Pelusium in Egypt.
• 46 BC, April: Pompeian survivors are defeated at Thapsus in North Africa.

Why it matters

Pharsalus destroyed Pompey’s army and his reputation, and his death removed Caesar’s only rival of equal standing. The war was not over, since the surviving Pompeians fought on in Africa and Spain, but from this point Caesar held the dominant position in the Roman world, a step towards his dictatorship and the end of the Republic.