XIX.--Caesar, having sent his cavalry on before, followed close after them with all his forces; but the plan and order of the march was different from that which the Belgae had reported to the Nervii. For as he was approaching the enemy Caesar, according to his custom, led on [as the van] six legions unencumbered by baggage; behind them he had placed the baggage-trains of the whole army; then the two legions which had been last raised closed the rear, and were a guard for the baggage-train. Our horse, with the slingers and archers, having passed the river, commenced action with the cavalry of the enemy. While they from time to time betook themselves into the woods to their companions, and again made an assault out of the wood upon our men, who did not dare to follow them in their retreat further than the limit to which the plain and open parts extended, in the meantime the six legions which had arrived first, having measured out the work, began to fortify the camp. When the first part of the baggage-train of our army was seen by those who lay hid in the woods, which had been agreed on among them as the time for commencing action, as soon as they had arranged their line of battle and formed their ranks within the woods, and had encouraged one another, they rushed out suddenly with all their forces and made an attack upon our horse. The latter being easily routed and thrown into confusion, the Nervii ran down to the river with such incredible speed that they seemed to be in the woods, the river, and close upon us almost at the same time. And with the same speed they hastened up the hill to our camp and to those who were employed in the works. XX.--Caesar had everything to do at one time: the standard to be displayed, which was the sign when it was necessary to run to arms; the signal to be given by the trumpet; the soldiers to be called off from the works; those who had proceeded some distance for the purpose of seeking materials for the rampart, to be summoned; the order of battle to be formed; the soldiers to be encouraged; the watchword to be given. A great part of these arrangements was prevented by the shortness of time and the sudden approach and charge of the enemy. Under these difficulties two things proved of advantage; [first] the skill and experience of the soldiers, because, having been trained by former engagements, they could suggest to themselves what ought to be done, as conveniently as receive information from others; and [secondly] that Caesar had forbidden his several lieutenants to depart from the works and their respective legions, before the camp was fortified. These, on account of the near approach and the speed of the enemy, did not then wait for any command from Caesar, but of themselves executed whatever appeared proper.