Nepos sighed. ‘Unfortunately I have to agree with you about that, madam. The Emperor would not accept an abandonment. It would harm him back in Rome. The Wall exists, for better or worse. We have to consider where we go from here, not where we would wish to have started from.’ He turned again to Xander. ‘We will not obliterate your precious monument, architect. But how would you modify it to correct its deficiencies?’

Xander, unfortunately, had retreated into a shell of hurt pride. He all but shouted at the governor, ‘The design cannot be modified! It must be expressed!’

Tullio raised an eyebrow, and a ripple of exasperation passed among the Romans in the room, Brigonius thought. Greeks will be Greeks.

Sabinus, ambitious, saw his chance. ‘If I may, governor? I’ve taken the liberty of drawing up a few modifications to Xander’s design that might accommodate the objections we’ve heard today.’ He held up a scroll. On Nepos’s nod of permission, he spread this on a low table before the governor. Brigonius saw it was a rough sketch done in charcoal of the Wall curtain, forts and ditches.

‘To begin with,’ Sabinus said, ‘the vulnerability at the rear. You can see that I’ve added a further earthwork on the south side.’ The cross-section he had sketched showed a ditch some twenty feet wide at the top and ten deep. There were mounds twenty feet across to either side, each set some thirty feet from the lip of the ditch. ‘This earthwork will be set back from the Wall to create a protected zone to the Wall’s south, an “annexe” if you will, where civilians will be excluded or controlled. There will of course be controlled crossing points and causeways at the forts.’

Annius nodded, pulling at his lip. ‘That would work. I’ve seen such designs before.’ He squinted at the architect. ‘And how long will this earthwork be?’

Sabinus said forcefully, ‘Why, it must shadow the Wall for its whole length. What use is it otherwise?’

Nepos held up his hand. ‘We’ll discuss the practical consequences later. I think we all agree that some system such as this will be necessary. Now, Sabinus, concerning your legate’s objections about the gates—’

Sabinus directed their attention to another corner of his sketch. ‘It is clearly impractical to have the major forts set back from the line of the Wall, and to have crossing points so narrow as the mile-forts. The solution is clear. We must build new forts, each large enough to house an auxiliary unit, along the line of the Wall itself.’ He showed a sketch of a fort, the classic rectangular shape lying astride the line of the Wall. ‘You can see that half the fort’s gates will give directly into the northern area, giving it the equivalent of six mile-fort gates. The unit will be able to deploy immediately from its fort into the north.’