VII. The centurions sent to reconnoitre had selected for the establishment of the camp the heights of Neuf-Mesnil. These descend in a uniform slope to the very banks of the river. Those of Boussières, to which they join, end, on the contrary, at the Sambre, in sufficiently bold escarpments, the elevation of which varies from five to fifteen mètres, and which, inaccessible near Boussières, may be climbed a little lower, opposite the wood of Quesnoy. The Sambre, in all this extent, was no more than about three feet deep. On the right bank, the heights of Haumont, opposite those of Neuf-Mesnil, descend on all sides in gentle and regular slopes to the level of the river. In the lower part, they were bare for a breadth of about 200 Roman paces (300 mètres), reckoning from the Sambre; and then the woods began, which covered the upper parts. It was in these woods, impenetrable to the sight, that the Belgæ remained concealed. They were there drawn up in order of battle: on the right, the Atrebates; in the centre, the Veromandui; on the left, the Nervii; these latter facing the escarpments of the Sambre. On the open part, along the river, they had placed some posts of cavalry. (_See Plate 10._) 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.