The beast stirred and increased his pace to a gentle trot. Behind, Stellanus and then Kastos repeated the order and a faint rumble took the place of the gentle clop and scrape of walking horses. Cato had scrutinised the ground in the valley before leaving the fort and had chosen to head for a bare ledge overlooking the head of the pass. The ground up to it offered little cover and seemed open enough to be usable by cavalry. He gently pulled on the reins to steer Hannibal in its direction and then looked towards the enemy. The horsemen had been seen by those still in the camp who were gesticulating and pointing at the two squadrons setting out from the fort. A moment later the first of the horns sounded the alarm to alert their comrades further up the valley. It took only a moment for the rearmost of the war bands, just over half a mile ahead, to stop and turn about. For a moment they hesitated and then Cato watched them fan out into a line facing his men. Most of the enemy carried shields and spears, but some carried more basic weapons and had no armour.

Cato led the Thracians towards the enemy line at a steady trot. More had stopped to turn and look back, uncertain how to react to the unexpected response from the garrison at Bruccium. Cato felt a moment’s satisfaction at the sight. Any seeds of confusion that he could sow would serve to hinder the enemy’s attack on the reinforcement column. Caratacus’s warriors would arrive piecemeal and there would be a chance for the reinforcements to deploy for battle rather than be caught strung out along the line of march. With luck, they might already have seen the smoke from the signal fire and paid heed to the warning.

Three more of the war bands had turned back to confront the Thracians and were hurrying across the open ground to take up position on the flanks of the line. The sight did not unsettle Cato as he had no intention of engaging with them. It would be suicide for such a small force of cavalry, well mounted and armed as they were, to charge headlong into an overwhelming mass of infantry. That was not Cato’s plan. The real danger was presented by the enemy horsemen. They heavily outnumbered the two squadrons and, more worryingly, would be able to outpace them. If they managed to attack and pin down the Thracians long enough for the infantry to intervene then it would all be over very swiftly and the destruction of the two squadrons would simply be the first Roman casualties of the day.