The men obeyed, and as the archers realised that no missiles were coming back at them they cautiously edged a little closer over the next few hours. The scorpio on the top level of the main gate spitted two archers and grazed another during the course of the day, but the few others to shoot missed as many times as they hit and Ferox sent word for the crews to calm down and wait. Instead a small number of men did duty on the walls and took care to dodge the arrows. Any looping high and coming over the top were collected and kept if they were good enough to use again. Those stuck in the timber of the ramparts and towers could wait for nightfall when it would be safer to salvage what they could. They could see the Dacians lifting artillery down from carts and working on other engines, but they were too far away to reach with anything apart from the monâkon and Ferox did not want it shifted lest they lose the concentration on the bridge, so they let the enemy work. Now and again the sound of hammering drifted over the walls. Only when some Dacians started setting up a timber palisade not far from the burnt out remains of the inn did he order the two bigger ballistae they had on the lower levels of the corner towers to lob some stones and shatter the still flimsy barricade.

Ephippus began work on his acropolis, starting with a turret in the alley behind the principia that was to be as high as the towers on the wall. He was also exercised by the thought of preparing plenty of boiling oil.

‘The fire would be dangerous, though, if we had braziers in the towers of the gates,’ he admitted.

‘If by dangerous, you mean we could easily burn ourselves to the ground, then yes,’ Claudia said.

‘Boiling water?’ Sabinus suggested.

‘Still the problem of heating it,’ Ephippus said. ‘I can rig up pulleys and ropes to haul cauldrons full of it onto the tower after it has been heated, but it will be delicate and easy to spill, so that those hauling the ropes will have to be careful. Or you could have men carry it in smaller vessels, either to pour on their own or add to a bigger one. It will lose heat all the time though.’

‘Some oil or tar to be flung down would be useful,’ Ferox said. ‘A flaming arrow would set it alight when we are ready. There is just about room for a small brazier on the walkway. If that falls back there is only turf to singe and not wood to roast.’

Ephippus snapped his fingers. ‘Hot sand!’

‘Sounds like the sort of treatment that doctors recommend for invalids,’ Claudia said. ‘Might hurt a bit, but surely would not kill.’

‘The Tyrians used it against Alexander’s men,’ Sabinus told them. He shrugged with embarrassment. ‘I do read sometimes. They say it got down tunics and inside armour, scorching men, so that they either fought on in pain or took off the armour and were vulnerable.’