C. Julius Caesar, De Bello Civili
Renatus du Pontet, Ed.

---

These things having struck a terror into the enemy; that he might not be always obliged to send his cavalry so far about to forage, the bridges lying about seven miles from his camp, he bethought himself of draining the river, by turning some of its water into canals thirty feet deep, so as to make it fordable. The work being almost completed, Petreius and Afranius grew extremely apprehensive of being entirely cut off from their provisions and forage, because Caesar was very strong in cavalry. They therefore thought proper to quit a post that was no longer tenable, and to carry the war into Celtiberia. What contributed still further to confirm them in this resolution was, that of the two contrary parties, concerned in the late war,those who had declared for Sertorius, still trembled at the name of the conqueror, and dreaded his power, though absent; and those who had attached themselves to Pompey, continued to love him for the many services he had done them: but Caesar's name was hardly known among these barbarians. Here they expected considerable reinforcements of horse and foot; and doubted not, by taking the advantage of places, to be able to protract the war till winter. In order to execute this plan, they collected all the boats to be found on the Iberus, and ordered them to be brought to Octogesa, a city on that river, about twenty miles from their camp. Here they commanded a bridge of boats to be built; and, having sent two legions over the Sicoris, fortified their camp with a rampart of twelve feet.