Cæsar, ignorant of the exact position where the Belgæ were encamped, directed his march towards the heights of Neuf-Mesnil. His cavalry preceded him, but the order of march was different from that which had been communicated to the Nervii by the deserters; as he approached the enemy, he had, according to his custom, united six legions, and placed the baggage in the tail of the column, under the guard of the two legions recently raised, who closed the march.
The cavalry, slingers, and archers passed the Sambre and engaged the cavalry of the enemy, who at one moment took refuge in the woods, and at another resumed the offensive, nor were ever pursued beyond the open ground. Meanwhile, the six legions debouched. Arrived on the place chosen for the camp, they began to retrench, and shared the labour among them. Some proceeded to dig the fosses, while others spread themselves over the country in search of timber and turf. They had hardly begun their work, when the Belgæ, perceiving the first portion of the baggage (which was the moment fixed for the attack), suddenly issue from the forest with all their forces, in the order of battle they had adopted, rush upon the cavalry and put it to rout, and run towards the Sambre with such incredible rapidity that they seem to be everywhere at once--at the edge of the wood, in the river, and in the midst of the Roman troops; then, with the same celerity, climbing the hill, they rush towards the camp, where the soldiers are at work at the retrenchments. The Roman army is taken off its guard.
Cæsar had to provide against everything at the same time. It was necessary to raise the purple standard as the signal for hastening to arms,[262] to sound the trumpets to recall the soldiers employed in the works, to bring in those who were at a distance, form the lines, harangue the troops, give the word of order.[263] In this critical situation, the experience of the soldiers, acquired in so many combats, and the presence of the lieutenants with each legion, helped to supply the place of the general, and to enable each to take, by his own impulse, the dispositions he thought best. The impetuosity of the enemy is such that the soldiers have time neither to put on the ensigns,[264] nor to take the covering from their bucklers, nor even to put on their helmets. Each, abandoning his labours, runs to range himself in the utmost haste under the first standard which presents itself.