The Roman cavalry, in the mean time, was forced to give ground. The Caledonians, in their armed chariots, rushed at full speed into the thick of the battle, where the infantry were engaged. Their first impression struck a general terror, but their career was soon checked by the inequalities of the ground, and the close embodied ranks of the Romans. Nothing could less resemble an engagement of the cavalry. Pent up in narrow places, the barbarians crowded upon each other, and were driven or dragged along by their own horses. A scene of confusion followed. Chariots without a guide, and horses without a rider, broke from the ranks in wild disorder, and flying every way, as fear and consternation urged, they overwhelmed their own files, and trampled down all who came in their way. Meanwhile the Britons, who had hitherto kept their post on the hills, looking down with contempt on the scanty numbers of the Roman army, began to quit their station. Descending slowly, they hoped, by wheeling round the field of battle, to attack the victors in the rear. To counteract their design, Agricola ordered four squadrons of horse, which he had kept as a body of reserve, to advance to the charge. The Britons poured down with impetuosity, and retired with equal precipitation. At the same time, the cavalry, by the directions of the general, wheeled round from the wings, and fell with great slaughter on the rear of the enemy, who now perceived that their own stratagem was turned against themselves. The field presented a dreadful spectacle of carnage and destruction. The Britons fled; the Romans pursued; they wounded, gashed, and mangled the runaways; they seized their prisoners, and, to be ready for others, butchered them on the spot. Despair and horror appeared in various shapes; in one part of the field the Caledonians, sword in hand, fled in crowds from a handful of Romans; in other places, without a weapon left, they faced every danger, and rushed on certain death. Swords and bucklers, mangled limbs and dead bodies, covered the plain. The field was red with blood. The vanquished Britons had their moments of returning courage, and gave proofs of virtue and of brave despair. They fled to the woods, and, rallying their scattered numbers, surrounded such of the Romans as pursued with too much eagerness. Night coming on, the Romans, weary of slaughter, desisted from the pursuit. Ten thousand of the Caledonians fell in this engagement: on the part of the Romans, the number of slain did not exceed three hundred and forty.