Caesar was pursuing Pompey into unfriendly territory. He had crossed the Adriatic Sea and so had to rely on the land for supplies. At Pharsalus there was finally a pitched battle to decide a victor.
The three accounts given all mention the same figures of troops. Caesar had 22,000 men with him, including 1000 cavalry, divided into approximately 80 cohorts (Caesar 3.89). Pompey is only given a specific figure in Caesar; generally he is described with double or more the numbers of Caesar, including 7,000 cavalry (Caesar 3.88).
Appian makes the comment that estimates of 400,000 are extravagant and he also raises an interesting point regarding nationality. He says the most reliable sources did not include foreigners. This would mean that most of these numbers are merely the Italian contingent (Appian 2.70). However, Appian’s sources do not appear so reliable in regard to some of his other claims, so perhaps this should be taken with a grain of salt.
The assertion that Pompey knew it was a ‘ploy’ is backed up by his general reluctance to engage in pitched battle. Caesar notes Pompey asserted that Caesar would be defeated before their lines met (Caesar 3.86). Of course, is he reducing the enemy as over-confident to make his own skills the more noticeable? It seems most likely that Pompey tried to avoid battle but could no longer convince his men. Any further analysis begins to become meaningless.
The accounts of deployment vary. All agree that Pompey faced Antonius on the Pompeian right. Caesar specifies that he fought opposite Pompey, which means he was not fighting with the tenth legion as he was wont to do (Caesar 3.89). The names of the centre do not match through the accounts. Plutarch mentions Lucius Calvinus facing Scipio (Plutarch 2.69) while Caesar states that Gn. Domitius was in command (Caesar 3.89). Unless one is another name for the other, someone has made an error. Again, we must assume that Caesar knew the names of his own officers.
Appian mentions Caesar joining the tenth legion which is a strong discredit to his account. It is becoming clear that he was referring to Caesar’s own history but other sources that were likely incorrect. Appian attributes the deployment of Pompey's horse on the wing to Caesar’s position; (Appian 2.69) however Caesar mentions a high banked stream guarding the opposite wing which allowed Pompey to concentrate his strong troops (Caesar 3.88).
At the initial charge, Pompey ordered his men to stand and remain in ranks. If he had been facing a less experienced army this may have succeeded in tiring and scattering the charging army. However, Caesar’s army was experienced enough to realise what was happening, halt halfway to redress ranks and then continue the charge (Caesar 3.92).
Pompey’s cavalry managed to push back Caesar’s easily, outnumbering them seven to one. Caesar had anticipated this and created a fourth line of troops using cohorts from the first line. These were instructed to reinforce the line wherever Pompey’s cavalry attacked (Caesar 3.84). Both Plutarch and Appian make specific mention of the soldiers not throwing their javelins but using them to spear the faces of the riders (Plutarch 2.69, Appian 2.71). Caesar does not. This technique would help to explain how approximately 3000 men and 1000 horse could drive off 7000 cavalry. Perhaps the troops were experienced enough to fight in this way, not requiring the specific order attributed to Caesar by Plutarch and Appian. Plutarch describes the retreat of Pompey’s cavalry as disgraceful, a result of their inexperience (Plutarch 2.71).
The victorious fourth line then wheeled into the Pompey’s exposed flank and, shortly after, the army broke. Plutarch and Appian break off here, the battle proper finished. Caesar continues to describe the day’s events and the pursuit of Pompey and his men. The only item of significance to the battle however is the evidence of Pompey’s early departure from the field. Apparently Pompey arrived back at the camp and set about issuing loud defensive orders long before the arrival of the rest of his army (Caesar 3.94).
1. Appian, ‘Civil Wars’
2. Plutarch, ‘Pompey’
3. Caesar, ‘Civil War,’