North again, the army spread out along the route of march in a column four miles long, following the track of an ancient road built by the legions in centuries past. At the vanguard rode the cavalry of the Equites Dalmatae and Equites Mauri, and behind them two cohorts of Legion I Minervia from the Rhine. Then came the commanders, the Augustus, his family and his staff, ringed by his elite bodyguard of Protectores, then the Praetorian Cohorts and a mounted guard of the Equites Scutarii. Following the emperor came the main legion force: detachments of VIII Augusta and XXII Primigenia; then II Augusta from the southern province of Britannia. The baggage train rolled after them, nearly two miles of carts and mules carrying tents and baggage, grain and water, and a full complement of siege artillery. With them went the slaves, and three hundred prisoners roped together and guarded by soldiers. The detachment of Legion VI Victrix brought up the rear, with the Equites Promoti as cavalry guard. And to either side of the march ranged the Alamannic warriors in loose order, with the horsemen of the Equites Batavi riding between them.
The army moved slowly, covering only twelve miles a day between camps. Castus was marching with his men at the rear of the column, and the air was thick with dust churned up by the men, wagons and horses ahead.
‘Can’t hardly breathe, or see,’ Modestus said in a muffled voice. He had the dampened end of his scarf between his teeth.
‘Get that rag out of your mouth, optio,’ Castus growled.
Modestus spat the scarf from his mouth, making a more than usually sour face. ‘Why do the German detachments always get to march at the front?’ he said. ‘It’s our province, isn’t it? We should be in the vanguard.’
‘Got to earn it,’ Castus told him. ‘But don’t worry – I’ll make sure you’re right up at the front when the Picts come down from the hills to chop us up.’
He had told the men about the Picts, and their habits. He was, after all, the closest the legion had to an expert. In particular, he had told them to avoid being captured at all costs – death would be far preferable to what the Picts did to their prisoners.
‘How come you survived then, centurion?’ one of the new men had asked. Stipo, the fullery assistant.
‘My neck’s too thick,’ he told them. ‘They’d blunt their blades trying to cut my head off.’
The men had laughed, nervously. Castus was glad that they were scared – they needed to be. This kind of warfare could too easily encourage a lack of caution. And he was determined that no men under his command would end up trapped in some ambush and slaughtered like his previous century. No – keep them nervous. Keep them alert. Let the Rhine detachments hold the vanguard if they wanted. Just keep the men together, Castus told himself, and deliver them safely to the battlefield.
By late afternoon the high black mountains filled the horizon to the north and west; the army crossed another river that flowed down out of the valley and built their entrenchments on the far bank. As the soldiers worked at the ditches they heard cheering from along the line of the fortification. A party of mounted men was circling the limits of the camp.
‘There’s the son of the Augustus!’ Remigius said, standing at the lip of the trench. All along the line, soldiers were throwing their muddy arms up in salute. Castus frowned. Was it right to salute a mere tribune like an emperor, even if he was an emperor’s son?
The cavalcade rode by, Constantine in the lead on his champ shy;ing grey, dressed in a gilded cuirass and a flowing white cloak. His head was bare, his long grave face set hard, and he ignored the salutations of the troops. Behind him was a heavy man with a big orange beard who wore a lot of gold.
‘And that’ll be our tame barbarian king,’ Modestus sneered. ‘What’s he called? Krautus? Rackus?’
‘Hrocus, I think,’ said Diogenes, leaning on his mattock. ‘His people were defeated on the Rhine five or six years back and he swore loyalty to Rome. Or to Constantius anyway.’
‘Centurions!’ a voice shouted. Victorinus, the tribune com shy;manding the detachment of the Sixth, came strutting along the trench line, gesturing angrily. ‘Get your men back to work! This isn’t a pay parade!’
Castus saluted quickly, and gave his men an encouraging growl. But as he turned back to the trench he saw the figure riding at the back of Constantine’s party, plainly dressed and unassuming. For a moment as he passed, the notary Nigrinus caught his eye and nodded in recognition. Then he was gone.
Thunder filled the sky at dusk, rolling in from the west. In the great marching camp the soldiers looked up apprehensively from their smoking fires between the tent lines and saw the lightning crackling and flickering over the dark peaks of the mountains. A gust of wind, heavy and charged, and then the rain came down, drumming off the tent leather and turning the ground to slippery mud.
What message was it, what omen? Castus considered it as he stood outside his tent, under the dripping hood of a cape. Jupiter the Thunderer, the lightning-hurler, was a friend of Rome. But an angry god all the same. Castus remembered the story of the emperor Carus, who had ruled back when he had been a boy: killed on campaign in Persia when his tent had been struck by lightning, or so the official version claimed. It was not wise to ignore divine warnings.
Hunching his shoulders, Castus made his way across the slippery turf to the southern perimeter of the camp, and the stretch of rampart allocated to his men. The barrier of sharpened stakes showed a jagged black outline with every flash of distant lightning.
Outside the stakes and the trench was utter darkness, filled with rushing rain. Castus stood and stared into it, letting his eyes trick him into seeing shapes moving out there. There were sentries standing six paces to his right and left, motionless in their capes and hoods, similarly gazing out into the night. The lightning glow flared off the tips of their spears. Castus paced slowly along the rampart.
‘Centurion!’ a voice said, one of the sentries at the rampart turning to salute. Castus recognised Diogenes’ pinched face under the hood and helmet rim.
‘Keep your eyes out there, not on me,’ he growled. The former teacher nodded smartly and looked back across the jagged stakes.
‘I don’t believe there’s anybody out there at all,’ Diogenes said. ‘Or for miles around either.’
‘Maybe so. But barbarians are very illogical – you never know what they might do…’
‘“They create a desolation, and they call it peace”,’ Diogenes intoned quietly.
‘What’s that?’
‘It’s from Tacitus. His account of the campaigns of Agricola, in this same country. I was thinking about it earlier today.’
Castus had never heard of Tacitus, or Agricola. But he was used to the schoolteacher’s stories by now – all the things he had learned in his books.
‘I rather wonder,’ the man went on, ‘what the people of this country must think of us. What do they tell themselves when they see a great fortress like this appearing overnight? Thousands of armed men, a city of tents, where there was only empty land…?’ He turned again to gesture back at the camp, until Castus nudged him and pointed out into the darkness.
‘Do they imagine,’ Diogenes went on, ‘that some race of terrible gods has appeared over the horizon, do you think?’
Castus shrugged. He had wondered similar things himself.
‘Just keep your eyes open,’ he said. ‘The only terrible gods you need to worry about are me and the tribune.’
He stayed on the rampart for another two hours, pacing the line back and forth until Modestus came to relieve him. Then he made his way across the camp again towards the medical station; two of his men had been injured by a panicked horse earlier in the evening and he needed to check on them. The tent lines spread all around him in their regular rows. The fires were out now, damped by rain, and the only lights showed from the wagon park and the imperial enclosure at the heart of the camp. Castus steered a path in the shredded moonlight, alert to the sensations around him: the smell of wet horses from the cavalry lines, wood ash and tent leather; the stink of the latrine trenches; the peaty mud underfoot. He considered what Diogenes had said: truly the camp was like a city, spread here in the darkness of a wilderness. But it was his own city – the only place he could call home.