‘Think the lads would notice nymphs, sir,’ Julius asserted from a few paces away.

The light was growing. Ferox could see almost all of the closest building in the canabae and the dim shape of the inn beyond it stood out in the white fog. He felt a breath of breeze on his face and wisps of the mist swirled across the grass in front of him. Then the wind died and the movement faded, but not before he saw something low scuttling between the buildings.

‘Bring in the picket,’ Ferox said. ‘Quietly though. Send someone out to bring them in.’

‘Sir?’ Sabinus was dubious, and Ferox had no energy to explain that he thought or sensed that he had seen someone in the canabae.

‘Now. And send men along the walls to get the scorpiones ready.’ During the night artillery was of little use because it was so hard to aim and there was no sense wasting bolts. Better to keep the engines covered up to protect them from the damp, but if an attack came now, it was clear enough to make a difference, and at least worth using the smaller machines. ‘Tell the men they’ll be coming soon – and send a runner to each of the other gates to alert them as well.’

‘Sir?’

‘Just do it, centurion.’

Sabinus went off. The fog seemed to glow brighter without making it any easier to see. Ferox squinted, out of habit rather than expecting it to make any difference. He saw the soldier walk out and call to the picket that they were relieved. That was good, for there was no sense in telling any enemies that they were waiting and ready. After the horn and trumpet calls, anyone with sense would know that the Romans were not asleep, but they would not be able to tell just how alert and prepared the defenders were.

The picket turned, each of them stiff as decayed old men from standing nearly still for so long, until the senior soldier remembered that so many eyes were watching and barked at them to look smart. They started to march back up the path.

Ox horns blasted, close and oddly loud as if echoing in the mist. There was a great shout, splitting into many individual cries as hundreds of dark figures came streaming up the slope towards the fort.

‘Oh shit!’ Julius gasped.

‘Run!’ Ferox shouted down at the picket. ‘Inside now!’ The soldiers stumbled into a lurching run, one at the rear dropping a spear. ‘Leave it! Get inside, now!’ The men broke into a sprint. Just one of the gates was open a few feet, with a team ready to close it the moment they were through.

‘Wait for the order!’ Ferox shouted, arm raised to signal even if few would be able to see it. The dark shadows of the enemy were becoming clearer, faint glints coming from spear points and the bosses of shields. Most were oval, not at all unlike the ones used by the auxilia and he could see plenty of men with helmets and probably armour. A dense knot of fifty or more were pelting up the road, closing with the picket and the open gate. Ferox never quite understood how time seemed to go fast or slow in a battle, but found himself imagining being put on trial for misconduct, with a stony-faced accuser throwing question after question. So when the enemy attacked you gave the order to run away? The order to leave a weapon behind? And it was you who had left the gate open so that the enemy could just run in?