Feathered shafts whipped through the air and thudded into the men pursuing Cato and the others, sending several sprawling, and causing the others to halt and stare up at the new danger. More arrows found their target and stopped them dead in their tracks. Cato looked away, back towards the sally port, and hurried on. The thick wooden door was already open and they thrust Petronius inside and then squeezed through after him and slumped to the ground gasping for breath.

‘Shut the port,’ Cato ordered.

The optio of the section tasked with guarding the sally port glanced out through the wall. ‘Where’s the rest of your men, sir?’

‘They should be here. Sycorax and the others.’

‘There’s been no sign of them, sir.’

‘Shut the gate,’ Cato repeated. ‘If they’re not back yet, then they never will be.’

The optio hesitated for a moment before he nodded and heaved the door back into position and drew the locking bars across and into their receivers. Cato forced himself on to his feet, drew some deep breaths and indicated Petronius. ‘Get him to the hospital immediately.’

As the optio carried out the order Cato made his way up on to the rampart and squeezed past the archers until he found Macro. The prefect smiled a greeting.

‘Cato! You made it. The rest of the men?’

‘I lost six from my party, and there’s been no sign of Sycorax.’

‘I know,’ Macro replied flatly. ‘But we’ll keep looking out for him and his men. Meanwhile, see there.’ He pointed out across the wall at the onagers. One was roaring with flames, the crackle clearly audible from where they stood. The other was still alight, but even as they watched the enemy was successfully smothering the flames. Shortly afterwards they had put that fire out.

‘Never mind,’ Macro said with a note of satisfaction. ‘It’ll be out of action for a while and the other one’s destroyed. That’s improved our chances no end. Good job, Cato.’

Cato tried to feel some satisfaction at his achievement, but he felt hollow and empty and bone weary. If Sycorax and his men had been lost, then the raid had been costly indeed, whatever it may have achieved. He felt guilty to have been the cause of the men’s death and for an instant he stared out over the wall, past the burning faggot and the bodies spread around it, out over the desert, trying to penetrate the darkness to the place where he had been forced to leave Glabarus, as if half expecting to see the man stagger out of the darkness. But Glabarus must be dead. And Sycorax and the others too. It would be better if they were dead, Cato realised. The enemy would show little mercy to any Roman soldiers they took alive.

He spread out his arms slightly and lowered his head as he leaned on the wall. Macro looked at him.