‘Of course, sir.’ Arrian beckoned to a trooper with laurel leaves tied around his spear shaft, the traditional mark of a herald.

‘See the one on the grey?’ Cerialis interrupted. He pointed to a lone rider some way ahead of the sparkling cataphracts. ‘I am sure that is Prince Arbandes. Saw him in the Lord Trajan’s camp a month or so ago.’

Crispinus shaded his eyes and stared, although since he had never seen the likeness of the prince, let alone his actual person, he would have to take Cerialis’ word for it.

‘It’s a young man,’ Ferox said. ‘Good rider, sits well. Riding a stallion. Bit too excited for his own good.’

‘The horse or the prince?’ Cerialis asked.

Crispinus frowned. ‘Holy Juno, you have good eyesight. The princess’ brother, then, not that kinship necessarily means concordia. Hmm. He might be less keen on our aid, but then again, he was at Trajan’s camp so might simply wish to make a deal of his own. Either way, he is clearly the man to reach. Don’t take any chances, my dear Arrian, but see what you can do.’

‘My lord.’

‘Wait!’ Ferox shouted. Another file of riders was galloping towards a pair of skirmishers from the ala, but this time as they closed an arrow flicked through the air and slammed into a trooper’s shield. The leading rider had turned away and sent another missile which went wide, but the man behind him was better or luckier and an arrow buried itself into the eye of the soldier’s horse, which reared in agony and threw him.

‘Bastards,’ Cerialis gasped.

More arrows followed and other files of archers were charging forward and shooting. Another horse was down, and a rider reeling back, an arrow in his thigh. Some troopers threw light javelins in response, but none found a target.

‘Is it a mistake?’ Rufus asked. Ferox could see that the prince was sitting on his horse, making no effort to ride forward and control his men.

Crispinus did not bother to answer the question. ‘Right, let’s drive these impudent bastards off. Push on, Cerialis, but keep close to the infantry. When we are closer to the walls, we charge. Let’s see those cowardly buggers try to dance out of the way of that. I’ll be with the legion if you need me.’

‘Skirmishers advance,’ Cerialis said to the trumpeter, who sounded the command. The men responded eagerly. Pairs of riders shot forward, and the abrupt attack surprised the closest horse archers. A couple went down under the javelins before the rest galloped back, turning round to shoot as they fled and a few of those arrows found marks. Cerialis ordered the horse archers forward. ‘Back them up, Ferox.’

‘Sir.’ Ferox trotted over to his men and waited for the auxiliary horse archers to pass before moving behind them. ‘We only charge to protect them,’ he ordered. ‘They have the range and we don’t.’

First blood had been drawn on each side, and it seemed to bring caution. The bands of Osrhoenes hung back, especially from the mounted auxiliary archers. One group looped wide and came at the infantry behind, until a volley of arrows brought a horse down and scared the rest off. As they fled, a scorpio from one of the carts spat its bolt and pitched a rider into the dust.