Tarquinius sat astride his mule, watching the water glide past at speed. Around him were Pacorus and many of the senior centurions on their horses. A ring of dusty warriors stood ready at their backs, secretly relieved to rest. To get a better view, the commander’s party had advanced to the river’s edge. Low trees and heavy vegetation grew right down to the water on both sides, restricting the view of the far bank.

‘The Hydaspes,’ announced Pacorus, gesturing expansively. ‘The eastern limit of the Parthian Empire.’

‘Alexander’s army finally came to a halt not far from here,’ said Tarquinius. ‘Because his troops would go no further.’

‘They were wise men,’ the commander answered. ‘Since deepest antiquity, the Indian kings have fielded huge armies. Far bigger than that damn Greek might have had.’

That damn Greek had more military talent in his little finger than you do in your whole rotten body, thought the haruspex.

‘Nothing has changed then,’ added Vahram drily.

‘Where are they, though?’ asked Ishkan.

Nervous eyes turned to Tarquinius.

‘The gods help you if this was a wasted march,’ growled Pacorus.

Vahram gripped his sword hilt, always keen to administer a quick revenge.

Tarquinius did not answer immediately. Surviving the torture had, if anything, helped him to consider everything for longer. Raising his head, the haruspex smelt the air. His eyes never still, he searched the sky.primus pilus’

Over the previous week, the weather had improved steadily. Spring was now well under way. In the fields belonging to the settlements that they had passed, the new wheat and barley was sprouting pale green shoots. Away from the colder climate of the mountains, the plants and trees were beginning to bloom. The river level would have fallen from its winter highs, the haruspex thought. It was about two months before the monsoon began. A perfect time for an army to cross safely.

Vahram was growing impatient, but Pacorus sat quietly astride his black stallion. Although he hated it, he had grown used to Tarquinius’ contemplative manner. Waiting for a few moments more would not change the course of their fate.

Tarquinius’ gaze was drawn to a solitary huge vulture flying over the far bank. Its appearance was striking, and unusual. Black circles dramatised its eyes; the rest of its head was white, while the neck and body were a pale brown colour. Even its long, diamond-shaped tail was distinctive.

Its presence had to be of significance.

Clutching a large tortoise in its talons, the vulture was climbing steadily into the air. When it had reached a height that he judged to be at least two hundred paces, it simply let go. The tortoise plummeted to the ground, its rigid shell guaranteeing a certain death. It was followed in a more leisurely way by the bird.

A striking example of intelligence, Tarquinius thought. A good lesson, when the odds seemed insurmountable.

In the eastern distance, over the trees, he glimpsed banks of massing thunderclouds. Tarquinius gave silent thanks to Tinia and Mithras. Since Vahram’s torture, divining had become more difficult. But his talents had not completely disappeared. ‘We’re late,’ he said. ‘There are shallows two days march to the south. They’re already crossing there.’

Ishkan’s tanned face paled. He knew where the ford was, but there was no way that Tarquinius could have: none of the Parthians would have mentioned it.

This was more proof that Tarquinius’ abilities were indeed real, thought Vahram. It was good that he had not killed the haruspex. Yet, he reflected, what faced them was as ominous as the fate which awaited any who killed such a man. A week earlier, the Forgotten Legion had abandoned the easily defendable pass through the mountains. The plan had been to reach the Hydaspes before the enemy, to deny them the crossing, or at least to make them pay dearly for it. Now, the realisation that the Indians were already on this bank hit home. And on the open ground by the river, their situation seemed even more vulnerable.

Pacorus set his jaw. A brave man, he was not about to run from his duty. Better to die honourably in battle against Parthia’s enemies than suffer an ignominious end at the hands of King Orodes’ executioners. He looked searchingly at Tarquinius. ‘Well?’ he said.

‘There is much to be done.’

Vahram sneered. ‘What can we possibly do, except die?’

‘Teach the Indians a lesson they will never forget,’ growled Pacorus.

Tired and footsore after yet another long march, the legionaries were unhappy at having to erect a marching camp a good mile from the river. The distance meant that those on water-hauling duty would spend far more time driving the mules to and fro than normal.

Romulus wasn’t concerned by the camp’s location. He had seen the Parthian horsemen take off at dawn, and knew that something was up.

When it was announced that every man would have to work the next day as well, the grumbling grew even louder. No one dared to question the order, however. Opening one’s mouth guaranteed severe punishment. Besides, it made sense to build defences.

The following dawn, they started. Brennus took to the task with gusto. In his huge hands, a shovel looked like a toy. But the amount of earth that he moved proved otherwise.

The Hydaspes was to shield the Forgotten Legion’s left flank. Under Tarquinius’ direction, the soldiers dug lines of deep curved ditches parallel to the riverbank, but about eight hundred paces away. This was the approximate width of the legion in battle formation. Branches were cut and trimmed, and dug into the bottoms of the defences. Facing outwards like one half of a circle, the trenches would protect the right flank. Without significant numbers of cavalry, this was the haruspex’ way of improvising. Inside the ditches, hundreds more sharpened wooden stakes were buried at an angle in the ground, jutting forward like so many crooked teeth in a crocodile’s jaws. In between them were scattered the caltrops, their iron spikes sticking jauntily into the air.

The dozen ballistae were split up, half facing forward along the line, and the rest placed to cover the area in front of the ditches. If necessary, they could be turned to cover the rear as well. The men that could be spared from other duties searched out suitably sized rocks by the river, and used the mules to haul them back. Pyramidal piles of this ammunition were built up beside each catapult. They varied from the size of a fist to lumps bigger than a man’s head. Aimed and fired correctly, all were deadly. Romulus had watched the artillerymen practising on many occasions and knew that the ballistae would play an important part in the battle.

The last, unexplained task was to dig a narrow yet deep trench from the river; it crossed right in front of where the Forgotten Legion would stand. Scores of long side channels were also excavated, until the ground looked like a field with too many irrigation channels. The final part of the trench, which would allow the Hydaspes to pour in and reach all its tributaries, was finished last. As the final clumps of soil were dug away, the trickle soon became a minor torrent, filling the channels to the brim.

With their purpose made obvious, there were weary smiles all round. By the morning, the area would be a quagmire.

The day of intense physical labour was over, allowing the legionaries to dwell on morbid matters – such as their future. And the battle that loomed ever nearer.

The remnants of Pacorus’ horsemen arrived back that evening, bloody and battered. They had been attacked by a far greater force of Indian cavalry, suffering heavy losses. And they reported that the army that followed in their wake was as large as Tarquinius had predicted. Or larger. It would arrive the next day.

A deep despondency fell on the legionaries. The haruspex had been proved correct yet again. Every single man in the Forgotten Legion but one wished the opposite.