Every single tiny scrap of advantage was to be wrung out.

The first five ranks of legionaries were armed with the long spears, while nearly two-thirds had a silk-covered shield. The precious fabric obtained from Isaac, the Judaean merchant they had encountered en route to Margiana, only covered five thousand shields or so. It would have to suffice. At the sides and rear, the soldiers manning the ballistae turned and twisted their machines, making sure the mechanisms were well oiled, the washers tightened to the maximum and the thick gut strings sufficiently taut. Arcs of fire were checked repeatedly, as were the piles of stones alongside. The old hands among the artillerymen had already paced out the ground in front, marking each hundred paces with a distinctively shaped rock or a stake driven almost completely into the earth. It gave them exact range markers, and would make their volleys far more lethal.

Finally, a party was sent to dig out even more of the trench near the river, allowing more torrents of water to pour through and causing all the carefully dug channels to overflow. Then the entire area was covered with small branches, concealing the digging that had gone on. Seeing the result helped to lift the men’s sombre mood a fraction.

They all waited.

It was a beautiful clear morning. The ominous red colour had lightened and then faded away, letting the sky turn its usual blue. The only clouds visible were groups of delicately shaped lines, very high up, but they still managed to dull the bright sunlight and kept the temperature pleasingly cool. The air was calm, and filled with a rich variety of birdsong from the trees along the riverbank. In the distance, a group of wild asses moved through the long grass, flicking their tails to keep flies at bay.

Romulus had already seen Tarquinius standing beside Pacorus, pointing here and there as they discussed the best battle strategy. There was no chance of talking with the haruspex, and Romulus had to hope that he and Brennus would be with him if the end came.

When it came, Romulus thought bitterly. He needed no ability to prophesy here, for the army that came to meet them was vast.

The Indian horsemen were the first to arrive. Riding small, agile ponies, the turbaned warriors carried a variety of weapons from javelins and bows to short spears and round or crescent-shaped shields. Bare-chested, dark-skinned, few wore any armour at all. Instead, a simple loincloth sufficed. Carefully keeping out of arrow range, they watched the Romans with dark, inscrutable eyes. These were skirmishers, highly mobile troops similar to the Gauls who had accompanied Crassus; their versatility could turn the course of a battle. There were at least five thousand of them, while Pacorus had perhaps two hundred and fifty horsemen remaining. Knowing this, many of the enemy confidently rode their horses down to the river to drink.

But they made no attempt to attack the Forgotten Legion. In their eyes, there was no need.

Pacorus kept silent, saving his men and the stones from his ballistae. Every single one was now more precious than gold.

Next to arrive were the battle chariots. Pulled by pairs of horses, they were larger than any Romulus had ever seen. Built from hardwood, and richly decorated with silver and gold inlay on their sides and solid wheels, they were essentially raised, enclosed battle platforms containing a driver and two or three warriors armed with spears and bows.

Romulus counted nearly three hundred of them.

As the chariots joined their cavalry comrades, shouts and jeers were hurled at the Roman lines. More and more voices joined in, until the mighty din filled the air. The exact words of the insults were unclear, but the meaning was crystal clear.

Following normal Roman tactics, the legionaries remained totally quiet. After a while, this had the effect of silencing the Indians and a strange peace reigned as the two sides watched each other warily. Some time later, the air filled with a low thunder.

The legionaries peered upwards, but there were no ominous-looking clouds in sight. Then it dawned on them that the noise was from the sheer number of infantry approaching. As the horizon to the south filled with the shapes of marching men, Romulus gradually picked out groups of archers, slingers and ordinary foot soldiers. The variety of weapons they carried was enormous: it seemed that no two men were armed the same. He saw axes, short swords, spears, even longswords like Brennus’ mighty one. There were pikes, spiked maces and knives with angled blades similar to those used by Thracian gladiators. Like the cavalry, most of the Indians wore no protective clothing at all. Some had leather armour and helmets and carried small, round shields. Just a few were wealthy enough to have mail or scale coats, but all were more lightly protected than the legionaries, with their heavy scuta and thigh-length chain mail. It didn’t matter.

There were at least thirty thousand of them.

The enemy numbers were bad enough, but this was not what had the Roman soldiers shifting uneasily from side to side. The low rumbling sound was not just from the men who drew ever nearer. It was being made by animals. Above the enemy ranks loomed the shapes of great, grey beasts.

Elephants.

There were dozens of them, guided by a mahout wielding a short staff topped with a sharpened hook. Each was wearing on its back a thick red fabric caparison, which was held in place by a band of leather that ran around its broad chest. Two or three archers and spearmen perched on this carpet, gripping tightly with their knees to stay in place. Every tenth beast carried a single passenger who was positioned above large drums hanging on both sides: these men’s sole purpose was to relay orders during battle. The animals’ small ears flapped from side to side as they lumbered along, giving them a deceptively gentle appearance. This contrasted with the heavy layers of moulded leather covering their heads and shoulders. To protect the mahout, a protective fan of the same material protruded upwards from the nape of the neck. As they drew nearer, it was possible to see that many of the elephants’ tusks were tipped with points or swords. A number even had spiked iron balls on chains dangling from their trunks.

They looked unassailable. Invincible. Romulus’ heart sank further, and even Brennus was dismayed; on either side of them, the legionaries looked downright terrified. The junior officers and Parthian centurions shuffled their feet uncertainly.

By now, the use of elephants in the arena was reasonably commonplace. There they killed or maimed at will. Even if he had not seen it for himself, every Roman knew of the huge beasts’ capacity to tear apart men like firewood. The Nubian king Jugurtha had used them in his fight against Rome, and no one ever forgot King Pyrrhus or the Carthaginians, enemies who had used elephants against the legions with devastating effect. It had given them a place in legend. And while Roman allies had used the great beasts alongside legionaries for many years now, most men here had never trained or fought with them.

Elephants were the ultimate battle weapon, able to smash aside almost any opposition – and the Indians knew it.

Romulus could almost sense their confidence as he watched the laughing, chattering men opposite. They were happy to delay the battle until all their forces had arrived.

Fearful muttering began in the Forgotten Legion’s ranks. Prayers and curses mingled in equal numbers. The whole pantheon of gods and goddesses were named: Jupiter, Mars and Minerva. Fortuna and Orcus. Neptune, Aesculapius and Mithras. Even Bacchus got a mention as every possible divine being was called upon. It made no difference. They were alone on the plain.

The solid lines of legionaries began to waver back and forth like reeds in the wind.