Soon the whirring sounds of slings being worked up to speed and the faint zipping of shots flying through the air was constant. But though the enemy warriors were whittled down, the onslaught served only to slow the speed at which the obstacles were being discovered and wrenched up from the riverbed. Every man who was struck by slingshot was quickly replaced from the host that lined the river bank. As the mass of Britons sat on the north bank, silent in the glare of the late afternoon sun, all the time more men, cavalry and chariots arrived and swelled their numbers, waiting for the river crossing to be cleared.

Macro watched the progress of the men in the ford, and when they came within javelin range he considered the impact that a volley of the deadly iron-tipped shafts might have. But they were too dispersed for him to be sure of maximising the effect and he decided to save the javelins for the attack that would follow the Britons’ clearing of the riverbed. Besides, as the range decreased so the effectiveness of the slingshot became more pronounced and the rate at which men were being struck down by the Romans delighted Macro. So far, he estimated, his century must have inflicted well over a hundred casualties, with poor Lentulus being the only Roman killed.

Despite their losses the Britons pressed forward, methodically finding and removing every one of the stakes. It was taking them far less time to clear the obstacles away than Macro’s men had spent planting them. A little more than quarter of an hour after they had begun the task, the enemy had almost reached the tangle of cut and sharpened wood that formed the barricade along the bank of the island. A few of the Romans leaned forward and thrust the points of their javelins towards the warriors.

‘Get back in line!’ Macro bawled at them. ‘You don’t do a thing until I tell you to!’

Their dangerous work done, the Britons in the river slowly backed away, keeping low behind their shields as the slingshot continued to splash into the water all around them. Behind them the native chieftains were already marshalling their men for the assault. Macro noted that the initial wave was made up of well-equipped men: nearly all had helmets and chain-mail vests. Caratacus must be in a hurry to get his forces across the river if he was prepared to throw his finest warriors in first. Beyond the three hundred or so men pressed close together at the edge of the river was a dense mass of slingers and bowmen. The latter were of little concern to Macro; their short bows might be an irritant to skirmishers, but they would never penetrate a legionary shield. The slingers, though, could inflict terrible punishment.