C. Julius Caesar, Gallic War

After spending several days in the same camp, the guards of the Bellovaci, learning that Caius Trebonius was advancing nearer with his legions, and fearing a siege like that of Alesia , send off by night all who were disabled by age or infirmity, or unarmed, and along with them their whole baggage. While they are preparing their disorderly and confused troop for march (for the Gauls are always attended by a vast multitude of wagons, even when they have very light baggage), being overtaken by day-light, they drew their forces out before their camp, to prevent the Romans attempting a pursuit before the line of their baggage had advanced to a considerable distance. But Caesar did not think it prudent to attack them when standing on their defense, with such a steep hill in their favor, nor keep his legions at such a distance that they could quit their post without danger: but, perceiving that his camp was divided from the enemy's by a deep morass, so difficult to cross that he could not pursue with expedition, and that the hill beyond the morass, which extended almost to the enemy's camp, was separated from it only by a small valley, he laid a bridge over the morass and led his army across, and soon reached the plain on the top of the hill, which was fortified on either side by a steep ascent. Having there drawn up his army in order of battle, he marched to the furthest hill, from which he could, with his engines, shower darts upon the thickest of the enemy.