For a moment Cato shared in his friend’s triumphant mood, and then he noticed that he could see almost across the entire extent of the camp. His heart sank as he faced Macro.

‘It’s getting light.’

‘All the better to see them run!’

‘It cuts both ways, sir. They’ll soon see that they outnumber us. We’d better begin to withdraw.’

‘Withdraw?’ Macro shook his head, and gestured to the men who had run past them, still cutting their paths across the enemy camp, killing all in their way. ‘We’ve beaten them, I tell you. We have to push on while their spirit’s broken.’

‘Of course, sir. As long as we’re ready to give the order to retreat when the time comes.’

Macro nodded and turned to run on with his men, beckoning to Cato to follow him. By the time they had reached the far side of the camp, dawn was spreading across the sky, and even though the sun had not breached the horizon there was plenty of light to illuminate the land stretching out around the fort.The camp was littered with bodies, and Romans were hunting down those who had hidden at first but were now making a break for it, sprinting for the gaps in the Roman lines. Spread out across the desert were thousands of men and horses, some of which had been mounted by Bannus’ Parthian allies. Already the enemy was slowing down, regrouping and starting to fight back against the scattered Romans. The cavalry squadrons of Scrofa and Postumus were also dispersed; many had ridden far too deeply amongst the enemy and were now in danger of being cut off.

Macro and Cato drew up at the edge of the camp, breathless as they surveyed the scene with growing anxiety.

‘We’ve done all we can do, sir,’ Cato panted. ‘We’ve won our victory. Let’s not lose it now. Give the order for the recall.’

Macro hesitated, torn between the desire to press the attack home, to keep killing the enemy and break their will, and the knowledge that his men were in danger now.

‘All right then,’ he conceded at last, and turned back towards the command party of standard bearers and trumpeters who had been following their prefect across the fort. He drew a breath and called out, ‘Sound the recall!’