‘Feisty piece, isn’t she?’ Tullio said.

‘You don’t know the half of it,’ Karus said dryly.

Brigonius faced Tullio. ‘Let’s get down to business, shall we? You heard her, prefect. This is the Emperor we’re dealing with. And the Emperor wants a stone wall.’

Tullio said heavily, ‘Listen, black-beard, the Emperor can want to build his Wall on the moon, but that doesn’t mean it can be done.’

‘Then what can you do?’

Annius was pulling his lip. In his dull way he seemed the more creative of the two, Brigonius thought, and was at least trying to come up with solutions. ‘Tell you what,’ he said slowly. ‘How about half in turf and half stone? You could probably manage that in the time. Then you get the best of all worlds, a complete defensive barrier in three years and a nice bit of stonework to impress the boss.’

Brigonius was about to reject this out of hand, but Xander said wearily, ‘Four-tenths.’

Brigonius turned to him. ‘What?’

‘Not half. Four-tenths in turf, the rest stone according to the plan.’ He tapped Tullio’s notebook. ‘That is feasible from the figures, if you are honest in your calculations, prefect. Besides I worked it out for myself earlier.’

Tullio took back the notebook and revised his figures quickly. ‘All right. Yes, four-tenths turf, six-tenths stone. Yes, you could do that.’

Xander turned to Brigonius. ‘This is the best we can do in the time.’ Karus said darkly, ‘And you knew this before we came in here? Why didn’t you say something when we put the plan before the Emperor?’

‘Because I didn’t know we would only have three years,’ Xander said. He sounded exhausted. ‘Severa didn’t let slip that little detail until the audience. What could I do, argue with her before Hadrian himself?’

‘It’s not so bad,’ Annius said cheerfully. ‘Everybody goes away happy. And you could always replace your turf with stone later.’

Karus growled, but subsided.

Brigonius glanced around. ‘All right,’ he said cautiously, not wishing to overstretch the consensus. ‘Then the question is, which half will be turf?’

After another hour’s discussion, and after a tankard or two of Tullio’s coarse German beer, they came a conclusion. From Segedunum at its eastern extremity, the Wall would run west as stone for forty-five miles, and then turf the rest of the way to the western coast. The eastern half of the Wall was closer to local sources of good stone - not least Brigonius’s own quarry - and the two soldiers regarded the security situation along this part of the border as more critical, so stone was appropriate for this stretch.

‘And besides,’ as Tullio pointed out, ‘the eastern half is where the Emperor is. He’s going to want to lay a foundation stone, not dig a lump of sod.’