They rode through wide pastures with many sheep. The flocks regarded them until they were close, then ran away bleating. Narses and Hairan spoke affably to the shepherds, but the herdsmen were uncommunicative and suspicious. Valens hoped it was caused by nothing more than their lonely calling on the margins of society.

About midday they spotted a dust cloud coming down from the north. It was tall and thin, and none of the soldiers doubted it was raised by a column of mounted men.

At least the plain was cut by many watercourses coming down from the mountains. They took shelter in one deep enough to conceal them from anyone not actually on its bank.

The stream was no more than a trickle. But its bed was wide. In the spring, when the snows melted on the heights, it would be full. Valens and Narses lay in the reeds at the top of the slope. They were bareheaded and their faces and hair were plastered with dust.

Slowly the pillar of dust crept across the plain.

They did not speak, and the only sounds were the wind moving through the reeds and the muffled coughing of the eunuch.

Narses broke the silence. ‘The westerners are unhappy about the eunuch.’

‘Unless the cavalry come very close they will not hear him over the noise of their own movement,’ Valens said.

‘They think eunuchs are ill-omened, that they bring bad luck, like monkeys. Aulus suggested they might smother him quietly one night.’

‘I will speak to them,’ Valens said. ‘The eunuch is useful to look after the boy, and I owe my life to his intervention.’

Now the mounted men were closer, the hidden watchers could hear the thud of their hooves, and clearly make out the individual riders. A troop of Persian horse archers, fifty men in columns of twos, led by an officer in magnificent armour and a standard-bearer carrying a large banner embroidered with an image of a panther or some other big cat.

Marching fast, alternating between a canter and a trot, they passed about a hundred paces away from the watercourse, and headed south. If they remained on that bearing, they would reach the foothills roughly where the Romans had emerged.

‘Warriors from the clan Karen,’ Narses said. ‘Good fighters, not as good as the Suren.’

‘A routine patrol?’ Valens asked.

Narses shook his head. ‘When I was stationed here, the only patrols were north of the wall, keeping an eye on the nomads. Of course, they could be looking for a raid from the Steppe that has slipped across the frontier. But, with the camp at the foot of the main track, it does not look good.’