48 BC

Battle of Pharsalus

Caesar defeats Pompey at Pharsalus

Caesar's charging legionaries saw that Pompey's line was not moving, stopped halfway to recover their breath, then resumed the charge — and won the day the Roman calendar called 9 August.

The fourth line that broke the cavalry

Near Pharsalus in Thessaly, on 9 August 48 BCE by the Roman calendar, Pompey deployed for battle after days of keeping close to favourable high ground. Caesar had begun preparing to move camp; he cancelled the march and deployed against him.

Pompey's infantry stood still to receive Caesar's charge while his concentrated cavalry tried to turn Caesar's exposed right flank. Caesar committed six cohorts formed into a separate fourth line, which routed the cavalry, killed the now-unprotected archers and slingers, and struck the Pompeian infantry from flank and rear.

Pompey abandoned the battlefield and then his camp. Caesar took the camp and began surrounding the Pompeian troops who had withdrawn to nearby high ground.

The August that was not August

The day is attested: the Fasti Amiternini give 9 August. But that is a date in the Roman civil calendar, and Ramsey and Raaflaub calculate its proleptic Julian equivalent as 7 June — so an unqualified, modern-looking "9 August" misleads about the season.

The place is less settled than the day. Ancient sources disagree over whether the battlefield should be called Pharsalus or Palaepharsalus, and its exact modern location remains debated.

The tactical narrative and the largest casualty figures come from Caesar, a participant with an interest in them.

Whose numbers, and who did the counting

Caesar credits Pompey with 45,000 infantry, about 2,000 distributed veterans and 7,000 cavalry, against his own 80 cohorts totalling 22,000 infantry and 1,000 cavalry. He claims to have lost no more than 200 rank-and-file soldiers and about 30 centurions, and to have inflicted about 15,000 dead and taken more than 24,000 surrenders, along with 180 standards and 9 legionary eagles.

Asinius Pollio, who was present, is reported by Plutarch to have counted no more than 6,000 Pompeian soldiers among the dead.

The remaining organized Pompeian force was denied access to water that evening and surrendered to Caesar at dawn the next day; Pompey had already torn off his commander's insignia and left with 30 horsemen.

Sources

Researched 23 Aug 2026 6 sources 2 audit passes Traditional date

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Traditional date. Conventionally dated here; the research places it at -0048-08-09.

What the sources leave uncertain

The Fasti Amiternini attest 9 August in the contemporary Roman civil calendar. Ramsey and Raaflaub calculate that as 7 June on the proleptic Julian calendar, so an unqualified modern-looking 'August 9' can be misleading.
Ancient sources disagree about whether the battlefield should be called Pharsalus or Palaepharsalus, and its exact modern location remains debated.
The principal tactical narrative and the largest casualty figures come from Caesar, an interested participant. Asinius Pollio, who was present, reportedly counted only about 6,000 Pompeian soldiers among the dead.