Hannibal’s flanks were heaving with the effort of climbing the slope but Cato urged him on, keeping up the pace, until at length they reached the ledge and the ground levelled out into a narrow strip of grass tussocks and patches of peat. He turned and looked down into the valley. The enemy infantry who were intent on cutting the Romans off from the fort were steadily picking their way up the slope towards them. Beyond the fir trees Cato could see over the saddle and his heartbeat quickened as he caught sight of the reinforcement column – a slender ribbon of scarlet shimmering with reflections from highly polished helmets. A small force of cavalry marched at the rear, protecting the carts and waggons of the baggage train. Seven or eight hundred men in all, Cato estimated with a sinking heart. He had anticipated that Legate Quintatus would send at least twice as many legionaries or auxiliaries to escort the reinforcements to the fort before turning back to Glevum. As it was, the slender hope that he had entertained that they would be strong enough to cut their way through to Bruccium was dashed.

Cato calculated that the reinforcements had been marching for nearly two hours and had covered perhaps five miles from their camp of the previous night. It was as well that they had not attempted to march on into the darkness to reach Bruccium. Otherwise they would have blundered into Caratacus’s army and been wiped out within earshot of the fort. As yet they seemed not to have seen the smoke rising from the fort, or at least they had not reacted to it. Nor had they seen the war bands hidden in the folds of the ground at the edge of the broad saddle, nor those waiting for them across the track leading down into the valley. They were marching blindly into the trap that Caratacus was laying for them.

Stellanus edged his horse forwards alongside the prefect and glanced briefly at the scene spread out before them before turning to Cato.

‘What are your orders, sir?’

‘We have to warn them of the danger.’ Cato twisted in the saddle. ‘Trumpets! Sound the attack! As loudly as you can!’

The men carrying the long hooked cavalry horns drew breath and raised their instruments to their lips. An instant later the short sequence of notes blasted out across the valley, echoing off the rocky crags above the Thracians. Cato pointed along the ledge.

‘We’ll ride out along there and skirt round the enemy ambush before we make for the column. Have the horns keep sounding as we advance.’

‘Yes, sir!’ Stellanus saluted.

Cato raised his spear and tilted it forward. ‘Second Thracian! Follow me!’