Sensing the soldiers' need for a rest, the legates finally ordered a halt. Men collapsed on to the ground, not caring that it was hot enough to burn. Fearing mutiny, the centurions did not attempt to move them for some time.

Eventually Bassius and the officers began to pace up and down, vine canes in hand. Armenia would get no nearer like this.

'Get up! Lazy bastards!' The words were the same, but since the superhuman effort of bringing the Second Cohort to safety, Bassius had lost his vigour. It seemed his last reserves had been spent, leaving only willpower to keep him going.

The legionaries groaned but did as he said. Bassius had earned their respect during the retreat and they were still willing to follow. Other centurions had more difficulty, but at last the battered army managed to get moving.

Its speed was now painfully slow and as the column ground on, ever more soldiers began to fall out of rank from sheer exhaustion. Some managed to struggle up, but the weaker ones remained sprawled on the baking sand. Cries for help filled the air, but few men had the strength to carry another. It was easier to look away. Tears again formed in Romulus' eyes when he recognised legionaries he had fought with during the campaign. Only Brennus' iron grip on his shoulder prevented him from trying to help many.

And so it went on. Half-dead figures littered the army's trail, left to cook in the sun. Clouds of vultures swiftly descended when it had passed. Loud, eager cries rose from the ugly birds as fights took place over the best pickings. Whether they waited until the prey was dead no one could tell.

At length the legions neared the base of an enormous dune that ran across their path, its sheer bulk halting their progress. Hundreds of feet of sand rose steeply into the air. The soldiers groaned aloud. It would be a long, hard slog.

'Climb!' The centurions roared, pointing upwards. 'Move!'

The front ranks shifted their yokes and began ascending. For the moment all they could do was obey. Maybe the promised mountains would be visible from the top.

Within fifty paces, Romulus saw a telltale cloud rising from behind the slope.

'Trouble.' Stomach churning, he nudged Brennus.

Suddenly everyone saw the dust. The army came to an abrupt standstill. Officers screamed in vain as the legionaries stared up with fascinated horror.

When Parthian archers emerged on top of the dune, a wordless moan escaped men's throats. They would be going no further. As the tired soldiers waited, awestruck, the entire ridge filled with the enemy.

'We 're finished,' swore Romulus. 'Can't fight them, can we? Might as well lie down and die now.'

A little shocked, Brennus regained his composure quickly. 'Can't be as bad as it looks,' he said.

Romulus spun to face Tarquinius, who regarded him steadily. The young soldier was furious. 'Did you know this would happen?' he snapped.

'No.' It was impossible to tell if the Etruscan was lying or not.

'Really? There are thousands of the bastards up there,' yelled Romulus. 'How could you miss seeing them?'

'The art of haruspicy is an uncertain one,' replied Tarquinius with a shrug. 'I've told you that before.'

Romulus' spirits plummeted. How could they live through another battle like the day before?

Then the Etruscan pointed.

A party of horsemen was making its way down the slope, hands held aloft to show they carried no weapons.

Romulus peered at the riders suspiciously. 'Are they offering parley?'

'Looks like it,' answered Brennus calmly.

'The breeze is more favourable now,' added Tarquinius. 'Although thousands more men will die today.'

'It's time to talk,' Romulus grumbled. 'We don't stand a chance otherwise.'

The friends held their breath as the Parthians came closer, the horses picking their way through the thick sand.

Crassus' position was obvious from the number of standards and red-cloaked officers, and the riders halted a hundred paces from it. They waited expectantly.

To Romulus' surprise, there was no response.

Men began to grow angry. The endless marching in blistering heat, exhaustion and the lack of water had been followed by the death of thousands at the hands of an unreachable enemy. Now, even when they were about to be slaughtered, it seemed that their leader would not talk to the Parthians. His arrogance had not completely evaporated.

With no cavalry remaining, Crassus had to rely on his bodyguards to carry orders. At last a pair of this elite came trotting along the column, sweating heavily in their gilded breastplates and leather skirts.

'Prepare for battle!' one wheezed every few steps. 'Back to the flat ground. Form a continuous line.'

'Piss off, son of a whore!'

'Who said that?' Both men skidded to a halt, hands on their swords.

'Go and fight those bastard Parthians yourself!'

There was an angry roar and more insults were thrown. So far, these hand-picked soldiers had seen no combat at all, which generated huge resentment among the rank and file.

'Where 's the ranking centurion?' The more senior bodyguard, an optio, tried to regain control.

Silently Bassius came forward, his phalerae prominent.

'Nobody disobeys a direct order from Marcus Licinius Crassus. Arrest those men!'

'You can call me sir. I didn't spend sixteen damn years in the legions for nothing!'

'Sir.'

'Go and do it yourself,' declared Bassius. 'You piece of shit.'

Huge cheers erupted from his men.

'Refusing to obey orders, Centurion?'

Bassius ignored him. 'Why has Crassus not sent a party to negotiate?'

More delighted shouts rose from the surrounding legionaries.

The two guards were blind to diplomacy.

'Crassus does not parley with desert savages.'

Bassius whipped out his gladius, placing its razor sharp tip under the optio's chin.

'Tell the general to go and talk with the Parthians. Himself.' He half turned. 'That right, boys?'

A swelling roar of approval moved down the line, the soldiers drumming their swords off scuta to show support. Those further away guessed what was going on and joined in. Romulus and Brennus did likewise. What was the point of dying in the Mesopotamian desert? They might as well retreat to Syria and survive.

A faint breeze had sprung up and Tarquinius saw that a number of small clouds had appeared in the sky. Engrossed with the standoff, no one else saw him frown. There were twelve.

The optio was a brave man. 'Crassus ignores demands from scum.'

'I've fought in more than ten wars, you miserable dog,' said Bassius, pressing harder with his gladius and breaking the skin. A drop of blood rolled down the iron.

He winced but did not back away.

'Crassus had best do what we say.' Bassius paused. 'Or he might end up like Publius.'

The optio glanced at his comrade.

Dozens of legionaries tensed and the second soldier carefully let go of his sword hilt. The men around them pounded harder on their shields. Crassus had promised them everything but delivered only hardship and death. Thousands of Parthians now waited to complete their annihilation. If the general would not parley, they would take matters into their own hands.

'You heard them.' The old centurion gestured at the column's centre. 'Now go and tell Crassus.'

Slowly the two guards moved away from the raised weapon and stalked back to Crassus' position. Bassius watched for a few moments before stepping into line.

'Jupiter!' Romulus let out a breath. 'Ever seen anything like that?'

Brennus shook his head. 'Shows just how bad it is, for a man like Bassius to mutiny.'

'Crassus decimated a unit that ran from Spartacus,' said Tarquinius. 'Interesting to see what he does about this.'