'Don't think I've ever seen a better spot for an ambush,' said Macro, hands on hips, as he surveyed the terrain around the ford. 'And there's just enough of the day left to make a clean sweep of it.'

'Thought you'd approve, sir,' smiled Cato.

They were standing with Tincommius on the edge of a small forested hill. Below them the ground sloped down to the track along which the Durotrigans would advance to ambush the convoy. Beyond the track the ground became soft as it fell away into a loop in the river. Half a mile to their right the river came close to the track before gently curving away, creating a natural bottleneck. To their left was the ford, and on the far side the track rose up towards a small ridge. The last century of Cato's cohort was just cresting the ridge and was soon out of sight. Cato had ordered them to cross a short distance down-river so that they would leave no trace of their passage on the far side of the ford. Macro's cohort was hidden along the treeline, with the scouts and their horses tucked down behind the forest, ready to charge round the base of the hill and close the trap. The mounted scouts had been given the pick of Verica's stables and would be able to run down any survivors with ease.

'The only way those bastards are going to get out of this is by swimming away,' Macro grinned, and turned to Cato. 'Of course, please don't feel obliged to attempt a pursuit down-river. '

Cato coloured. 'I just haven't had the time to learn properly. You know I haven't.'

'I'm just wondering if you'll ever find the time. I've seen cats with more affection for being dunked in water.'

'One day, Macro, I swear it.'

'You can't swim?' Tincommius was surprised. 'I thought all you legionaries could.'

Cato gave him a thin smile. 'Meet the exception that proves the rule.'

'Heads up!' Macro craned his neck to the right. A mounted scout had emerged round the corner of the hill and was galloping along the track, bent low over the flying mane of his horse. As he approached, Macro and the others trotted down the slope to intercept him. The man reined in, slewing his horse to a stop. He spoke very quickly, snatching for breath as the Celtic words tumbled from his lips. When he had finished, Tincommius asked him a brief question and then directed him to the cover of the forest. The scout dismounted and led his horse up the slope and out of sight.

'Well?' asked Macro.

'They're two miles down the track, marching in one column with a couple of riders a few hundred paces ahead of the main body. As we were told, about five hundred men.'

'Cato, you're going to have to bag those riders before they can raise the alarm.'

'That'll be tricky.'

'Let me deal with them.' Tincommius patted the handle of his dagger.

'You?' Cato asked. 'Why?'

'I want to strike the first blow for my people.'

'No.' Macro shook his head. 'You're not trained for it. You'd probably just give the game away. Besides, I need you close to me, to translate.'

Tincommius looked down and shrugged. 'As you wish, sir.'

'Right then, Cato,' Macro slapped him on the shoulder, 'back to your men. You know what to do. Just make sure we catch them both sides of the ford. See you later.'

Cato smiled, and then turned to jog down the track towards the ford, while the others climbed back up to their hiding place. Since he had begun to exercise again the pain in his side had become ever more pronounced, and the quick cross-country march of the last two days to intercept the Durotrigans had made it even worse.

Cato splashed down into the shallows at the edge of the ford and waded across the river. He emerged, dripping, on the far bank and ran up the track towards the brow of the low hill that followed the line of the river on each side. In the long grass on the reverse slope the centuries were already formed up in a line parallel to the river, in accordance with his orders.

'Lie down!' he shouted in Celtic, and the Atrebatans dropped out of sight into the grass.

'Bedriacus! On me!'

The wolf's head standard rose up from the ground, followed moments later by the grinning features of the hunter. He trotted over to the centurion and Cato indicated that they crouch down, before scurrying back up towards the crest of the ridge. As he reached the top, he moved to the side of the track and dropped on to his stomach. Bedriacus got down beside him, carefully laying the standard in the grass. Cato unstrapped his crested helmet and put it to one side as he propped himself up on his elbows and fixed his eyes on the track on the other side of the ford. For a moment his eyes wandered along the treeline where Macro's cohort was concealed but Cato saw no sign of movement. Everything was set, and the scene looked peaceful enough to allay the suspicions of the Durotrigans when they appeared.

The sun was low in the sky, and already the grass was tinged with a faint orange hue as a light breeze stirred the slender blades of green. There would be plenty of daylight for a few hours yet, and the Durotrigans would be wiped out long before they could escape under cover of darkness.

Half an hour must have passed before the advance scouts of the enemy column appeared half a mile from the ford. In all that time Bedriacus had kept absolutely still. Only his eyes moved, restlessly scanning the landscape, and Cato began to have more confidence in the hunter. Cato felt the faintest touch of a hand on his arm and looked round at Bedriacus. He nodded gently towards the track and Cato's eyes searched for a moment before they fixed on the distant figures. Two men on horseback, side by side, slowly approached round the curve of the hill. They came on cautiously enough, glancing around them as they approached the ford.

'Bedriacus…' Cato said softly.

'Sa?'

Cato pointed to the scouts and drew his finger across his throat, and then indicated the track just down from the crest. Bedriacus smiled his gap-toothed smile and nodded, shuffling away from Cato and easing his way behind a large tuft of spiky grass right at the edge of the track. Then he lay perfectly still again.

Peering carefully through the grass, Cato watched the scouts walk their horses up to the far side of the ford, no more than a hundred paces away. They stopped and exchanged some words, gesturing back in the direction of the main force of the Durotrigans. Then, both men slid from the backs of their mounts and led them into the pebble-bottomed shallows of the river. While the horses lowered their muzzles into the lazily sparkling current, one of the scouts waded a few steps downstream, untied his waist cords and unleashed a long golden arc of piss with a grunt of satisfaction that carried up the slope to Cato. When he had finished, the man just stood staring down-river for a moment and then hitched up his breeches and retied the waist cord. Making his way back to the riverbank, he sat beside his companion and gazed across the ford. Cato forced himself to keep still. With the sun low in the sky behind the scouts the crest of the hillock would be well lit, making any sudden movement easily detectable. But, as time crawled by, the scouts gave no sign that they were at all suspicious.

Something glittered in the distance and Cato shifted his gaze beyond the two scouts. A column of chariots came bumping along the track and the low sunlight was reflecting brilliantly off the highly polished bronze helmets of warriors riding on the small platforms above the axles. Fourteen chariots had come into sight before the first of the infantry appeared. With the sun almost at their backs Cato had to squint to make out any details of their equipment. His heart lifted as he saw that the vast majority were lightly armed and only a few sported helmets. Their shields were slung across their backs, and they carried a mixture of weapons, mostly swords and spears, together with large haversacks for their marching rations. At the rear of the loose column was a small band of more heavily armed warriors, and behind them a score of mounted men. Nothing that the Atrebatans could not handle, provided they stuck to their training and kept formation.