Plutarch Caesar 53

[1] However Scipio was encouraged by these advantages to hazard a decisive battle: so, leaving Afranius and Juba encamped separately at a short distance apart, he himself began fortifying a camp beyond a lake near the city of Thapsus, that it might serve the whole army as a place from which to sally out to the battle, and as a place of refuge.

[2] But while he was busy with this project, Caesar made his way with inconceivable speed through woody regions which afforded unknown access to the spot, outflanked some of the enemy, and attacked others in front. Then, after routing these, he took advantage of the favourable instant and of the impetus of fortune, and thereby captured the camp of Afranius at the first onset, and at the first onset sacked the camp of the Numidians, from which Juba fled. Thus in a brief portion of one day he made himself master of three camps and slew fifty thousand of the enemy, without losing as many as fifty of his own men. ¹

[3]
  This is the account which some give of the battle; others, however, say that Caesar himself was not in the action, but that, as he was marshalling and arraying his army, his usual sickness laid hold of him, and he, at once aware that it was beginning, before his already wavering senses were altogether confounded and overpowered by the malady, was carried to a neighbouring tower, where he stayed quietly during the battle. Of the men of consular and praetorial rank who escaped from the battle, some slew themselves at the moment of their capture, and others were put to death by Caesar after capture.