'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.

'You're done in, lad. Best go and get some rest.'

'I'll wait a while, sir. In case Sycorax makes it back.'

'I'll look out for him,' Macro said gently. 'You get some rest, Centurion. That's an order.'

Cato looked up and met his friend's eyes. He thought about protesting, then knew that Macro was right. There was nothing to be gained by tiring them both out.

'Very well, sir. Thank you.'

Cato took one last look at the burning onager and hoped that he had bought his comrades enough time to justify the sacrifice of Glabarus, Sycorax and the others. He'd know soon enough, when the next day dawned.

07 The Eagle In the Sand

As soon as the flames on the surviving onager had been extinguished the Parthian engineers started making repairs, and the sounds of their labours could be heard through the rest of the night. At first light Macro and Cato climbed the corner tower to survey the results of the previous night's raid. The first onager was little more than a black, charred skeleton. A short distance away the other onager almost looked undamaged as the enemy swarmed round it. Fresh torsion cords had been fitted and they were busy tightening them with long levers, several men to each, straining every muscle to wring the very last measure of power from the weapon's throwing arm.

'Won't be long before that's back in action,' Cato muttered. 'They've been busy.'

'You don't know the half of it,' Macro replied, and gestured towards the ground in front of the fort. 'Shortly after you returned, they began removing the traps. We tried throwing torches out for the archers to see their targets, but the enemy had screens, and just ducked behind them the moment the first arrows began to fly.They only stopped at daybreak.'

Cato looked down and saw that a large swath of the defences had been cleared, the pits filled in and the caltrops removed. Bannus and his men could now approach almost as far as the ditch on the side of the fort where the ruined gatehouse stood. When the time came for the enemy to make their attack, little would stand in the way between them and the men of the cohort. Cato glanced at the gatehouse. Some attempt had been made to prepare a breastwork out of the rubble. It continued the line of the wall and Macro had posted enough men behind it to convince the enemy that the Romans would not easily surrender the gatehouse. A shallow bluff, Cato realised. The moment the repaired onager was ready to recommence the bombardment, it would batter down the breastwork and send the Romans scurrying for the shelter of the inner wall.

'No sign of Sycorax and the others?'

'Not yet,' Macro replied quietly. 'I don't expect we'll be seeing them again.'

Cato shook his head wearily. 'All those men lost, and we only managed to destroy one weapon.'

'One destroyed. One damaged.That's a good result by any measure, Cato. You've halved the weight of their bombardment and set them back a while until the repairs are complete. You and the others did as much as could reasonably be expected. So don't go and put yourself down, and don't rubbish the effort of those men who didn't make it back last night,' Macro said frostily. 'In the circumstances we had to try something, or just sit here and wait for them to come to us. We did the right thing.'

'Maybe, but if it just postpones the inevitable, then that's small comfort. I wonder if the men who…' Cato's voice faded as his gaze was drawn to a group of men working close to the burned onager. They had been busy cutting away the salvageable timber and constructing something on the ground next to the remains of the siege weapon. Now several small parties of the enemy were distributing lengths of jointed wood, fashioned in some kind of crosspiece. He pointed them out to Macro.

'What are they up to?'

The older officer strained his eyes for a moment and shook his head. 'Beats me. Framework for a ram housing, maybe.'

As they watched there was a brief commotion in the enemy camp and then a crowd of men marched towards the siege engines. As they got closer Cato could see that they were jostling a small party of captives with dark tunics and smeared skin. He felt a sinking feeling in his guts as he recognised one of the prisoners.

'I think that's Sycorax…'

Even as he watched them approach the hastily arranged constructions lying on the ground Cato could guess what was coming next, and he felt his stomach clench and feared he was going to be sick. The prisoners were split up, one man being dragged to each crosspiece. The tunics were torn from their bodies and then they were held down against the wood while heavy iron nails were driven through their wrists and ankles. The sound of the hammer blows rang out over the open ground, accompanied by terrified screams of agony from the Roman prisoners.

Neither Macro nor Cato spoke as they watched the first of the makeshift crosses raised into position, and lowered heavily into the post hole that had been dug for the base. There was an audible thud and the forceful impact caused one of the prisoner's wrists to tear loose so that his mangled arm dropped and he gave a piercing shriek. The enemy were not fazed by the incident. One of them calmly set a siege ladder up against the rear of the cross, climbed up, reached over the beam to grasp the torn arm and nailed it back into place. Fortunately the torment of the prisoner was such that he passed out after the first few blows, to the relief of his comrades watching in horror from the walls of the fort. The respite was short-lived, however, as one by one the other prisoners were raised up until a line of crosses extended some distance in front of the surviving onager.