C. Julius Caesar, Gallic War

The siege having been impeded by so many disadvantages, the soldiers, although they were retarded during the whole time by the mud, cold, and constant showers, yet by their incessant labor overcame all these obstacles, and in twenty-five days raised a mound three hundred and thirty feet broad and eighty feet high. When it almost touched the enemy's walls, and Caesar, according to his usual custom, kept watch at the work, and encouraged the soldiers not to discontinue the work for a moment: a little before the third watch they discovered that the mound was sinking, since the enemy had set it on fire by a mine; and at the same time a shout was raised along the entire wall, and a sally was made from two gates on each side of the turrets. Some at a distance were casting torches and dry wood from the wall on the mound, others were pouring on it pitch, and other materials, by which the flame might be excited, so that a plan could hardly be formed, as to where they should first run to the defense, or to what part aid should be brought. However, as two legions always kept guard before the camp by Caesar's orders, and several of them were at stated times at the work, measures were promptly taken, that some should oppose the sallying party, others draw back the towers and make a cut in the rampart; and moreover, that the whole army should hasten from the camp to extinguish the flames.