The distant horsemen parted, and from within the group a man on the ground staggered forward, his arms tightly bound behind him. A rope curved up from a halter round his neck and into the hand of the rider walking his beast alongside. The mounted man, like his companions, was thickly robed in black and wore a strange headpiece that bore an elaborate pair of antlers that made him look like a thin tree stripped for winter. The two figures approached the fort, the man on foot stumbling to retain his balance without choking on the tether held tightly by his captor.

‘What’s going on?’ Macro had arrived, breathing hard. ‘Who are they?’

‘Don’t know, sir.’

‘Who called out the guard?’

‘Figulus, sir.’

Macro turned and looked for the recruit. ‘Figulus! Over here! Smartly does it, lad!’

Figulus doubled along the rampart and drew up in front of his centurion with a thud as he grounded his javelin and stood stiffly at attention. Macro surveyed him with a harsh expression. ‘Did you call out the guard cohort?’

‘Yes, sir.’ The legionary steeled himself for a stiff bollocking from his centurion. ‘Sorry, sir.’

‘Sorry? What are you fucking sorry for, lad? You’ve done well. Now back to your position.’

It took a moment for the slow-witted youngster to realise that he had been praised, and his face split into a gap-toothed grin.

‘Today, Figulus! Today!’

‘Oh, right, sir!’ He turned and trotted away, leaving his centurion shaking his head in thin-lipped wonder at the quality of some of the men he had been forced to take into his century to bring it up to strength. Beyond Figulus he caught sight of the red crest of a tribune bobbing above the cluster of helmets, brightly gilded in the sunlight. Plinius pushed his way through the throng on the rampart and leaned up against the palisade, staring at the two figures now little more than half a mile from the outer ditch. The man on foot wore the tattered remains of a red tunic fringed with gold thread. Plinius turned and caught sight of Macro.

‘That man in front’s a Roman! Pass the word for the cavalry scouts to be mounted and ready for pursuit. I’m going to get the legate.’

‘Yes, sir!’ Macro turned to Cato. ‘You heard him. Go find the scouts’ centurion and give him his orders. I’ll take charge of the men up here. Can’t have them behaving like a bunch of louts at a chariot race.’

As Macro started bawling out curses and orders to the men milling along the rampart, Cato made for the stables, up by the legate’s tent. By the time he returned, the men on the wall were evenly dispersed and watching the distant figures making their way across the snow towards the fort. The legate and the breathless senior tribune had arrived moments before, and were staring silently at the spectacle.