XLI.--In two days after Caesar came to the camp with nine hundred horse, which he had retained for a bodyguard. The bridge which had been broken down by the storm was almost repaired, and he ordered it to be finished in the night. Being acquainted with the nature of the country, he left behind him six cohorts to guard the bridge, the camp, and all his baggage, and the next day set off in person for Ilerda, with all his forces drawn up in three lines, and halted just before the camp of Afranius, and having remained there a short time under arms, he offered him battle on equal terms. When this offer was made, Afranius drew out his forces, and posted them on the middle of a hill, near his camp. When Caesar perceived that Afranius declined coming to an engagement, he resolved to encamp at somewhat less than half a mile's distance from the very foot of the mountain; and that his soldiers whilst engaged in their works, might not be terrified by any sudden attack of the enemy, or disturbed in their work, he ordered them not to fortify it with a wall, which must rise high, and be seen at a distance, but draw, on the front opposite the enemy, a trench fifteen feet broad. The first and second lines continued under arms as was from the first appointed. Behind them the third line was carrying on the work without being seen; so that the whole was completed before Afranius discovered that the camp was being fortified. XLII.--In the evening Caesar drew his legions within this trench, and rested them under arms the next night. The day following he kept his whole army within it, and as it was necessary to bring materials from a considerable distance, he for the present pursued the same plan in his work; and to each legion, one after the other, he assigned one side of the camp to fortify, and ordered trenches of the same magnitude to be cut: he kept the rest of the legions under arms without baggage to oppose the enemy. Afranius and Petreius, to frighten us and obstruct the work, drew out their forces at the very foot of the mountain, and challenged us to battle. Caesar, however, did not interrupt his work, relying on the protection of the three legions, and the strength of the fosse. After staying for a short time, and advancing no great distance from the bottom of the hill, they led back their forces to their camp. The third day Caesar fortified his camp with a rampart, and ordered the other cohorts which he had left in the upper camp, and his baggage to be removed to it.