‘This is going to be rough, lads! Keep your shields up until I give the order. We’ll use the rear rank javelins only; we’ll need to use the rest as spears The javelins will have to go in quick, so I’ll only give the order to loose. Throw it in and get down again until that lot reach the barricade.’ He looked round at his men. ‘Understand?’

The nearest men nodded, and a few men mumbled their acknowledgement.

‘Bullshit! I can’t hear you! Do you bastards understand me?’

‘Yes, sir!’ every man in his century roared back.

Macro smiled. ‘Good! Once they get close enough to go hand to hand, I want you to give them a fucking good kicking. They’ll not forget the Third Century in a hurry!’

‘Here they come!’ someone shouted out, and all eyes turned towards the far bank. The native warriors lurched forward, down the track and then splashed into the river. As they came on the Britons screamed out their battle cries, accompanying their challenges with a deafening clatter of weapons being struck against the metal rims of their shields. There were no horns to urge them on - they were making enough noise to drown out any encouragement from their own side. They were close enough for the Romans to make out the cold determined expressions on the faces beneath the helmets. These were not the usual run of wild woad-stained barbarians with lime-washed hair; they knew their business and would be formidable opponents.

Macro glanced beyond the front rank of the enemy surging through the water and saw the slingers begin to whirl their thongs over their heads.

‘Get down!’

The Romans dropped behind their shields as the air was filled with the zipping sound of slingshot hurtling towards them. The volley was well aimed and only a handful of shots cracked through the branches overhead. The rest struck the Roman shields in a rattling cacophony of thuds. The bombardment continued remorselessly and Macro had to take the risk of being struck each time he glimpsed round his shield to check the progress of Caratacus’ assault wave. The enemy waded steadily across the ford, no longer slowed down by the underwater obstacles. This was no wild charge, and the warriors advanced with deadly intent, not needing the cheap morale boost of a frenzied Celtic rush towards the thin Roman line.

The slingshot barrage abruptly slackened and then stopped and Macro peered cautiously over the rim of his shield. The enemy was no more than twenty paces away, thigh-deep in foaming spray, and the slingers no longer dared to loose their missiles at the Romans for fear of striking their own men.

‘Hit ‘em back!’ Macro called out. ‘Javelins! Slingers, loose!’