Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Thus the battle of Pharsalus was fought on the 9th August 706, almost on the same field where a hundred and fifty years before the Romans had laid the foundation of their dominion in the east.(31)
31. Cf. III. VIII. Battle of Cynoscephalae
Pompeius rested his right wing on the Enipeus; Caesar opposite to him rested his left on the broken ground stretching in front of the Enipeus; the two other wings were stationed out in the plain, covered in each case by the cavalry and the light troops. The intention of Pompeius was to keep his infantry on the defensive, but with his cavalry to scatter the weak band of horsemen which, mixed after the German fashion with light infantry, confronted him, and then to take Caesar's right wing in rear. His infantry courageously sustained the first charge of that of the enemy, and the engagement there came to a stand.
Labienus likewise dispersed the enemy's cavalry after a brave but short resistance, and deployed his force to the left with the view of turning the infantry. But Caesar, foreseeing the defeat of his cavalry, had stationed behind it on the threatened flank of his right wing some 2000 of his best legionaries. As the enemy's horsemen, driving those of Caesar before them, galloped along and around the line, they suddenly came upon this select corps advancing intrepidly against them and, rapidly thrown into confusion by the unexpected and unusual infantry attack,(32) they galloped at full speed from the field of battle.
32. With this is connected the well-known direction of Caesar to his soldiers to strike at the faces of the enemy's horsemen. the infantry--which here in an altogether irregular way acted on the offensive against cavalry, who were not to be reached with the sabres--were not to throw their -pila-, but to use them as hand- spears against the cavalry and, in order to defend themselves better against these, to thrust at their faces (Plutarch, Pomp. 69, 71; Caes. 45; Appian, ii. 76, 78; Flor. ii. 12; Oros. vi. 15; erroneously Frontinus, iv. 7, 32). The anecdotical turn given to this instruction, that the Pompeian horsemen were to be brought to run away by the fear of receiving scars in their faces, and that they actually galloped off "holding their hands before their eyes" (Plutarch), collapses of itself; for it has point only on the supposition that the Pompeian cavalry had consisted principally of the young nobility of Rome, the "graceful dancers"; and this was not the case (p. 224). At the most it may be, that the wit of the camp gave to that simple and judicious military order this very irrational but certainly comic turn.
The victorious legionaries cut to pieces the enemy's archers now unprotected, then rushed at the left wing of the enemy, and began now on their part to turn it. At the same time Caesar's third division hitherto reserved advanced along the whole line to the attack. The unexpected defeat of the best arm of the Pompeian army, as it raised the courage of their opponents, broke that of the army and above all that of the general. When Pompeius, who from the outset did not trust his infantry, saw the horsemen gallop off, he rode back at once from the field of battle to the camp, without even awaiting the issue of the general attack ordered by Caesar. His legions began to waver and soon to retire over the brook into the camp, which was not accomplished without severe loss.
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