At last Agrippina found herself facing the languid water. But the river itself was crowded. Warriors stalked up and down in water that lapped up to their knees. Some of them waved swords at the Romans on the far bank, or slapped the water with their blades. Women pulled faces at the invaders, with tongues extended and eyes bulging. Even children were showing their little arses.

A handful of Romans on the far bank, washing their feet in the river, seemed unperturbed. They laughed and catcalled and pointed out to each other particular sights that amused them: a fat old warrior doing a war dance in the water, a dog that gambolled in the spray thinking everybody was playing this sunny afternoon.

Agrippina pointed out a mother duck who serenely swam down the river's centre followed by a line of her young, their formation as orderly as a Roman legion. 'All this nonsense doesn't even frighten the ducklings,' she said dryly.

'Perhaps it makes these big men feel better about themselves,' Braint murmured.

Nectovelin said, 'And Caratacus?'

'There.' Braint pointed.

The two princes stood knee-deep in the water, working their way through a heap of weaponry. They destroyed each item, snapping dagger blades, bending swords in two, smashing shields with axes, before hurling the pieces into the deep water. Agrippina saw a priest close to the princes; the druidh held his hands out wide, as if to embrace the river itself, and he chanted as the princes worked.

Amid the ludicrous spectacle of the posturing warriors, Agrippina found this ceremony dignified, oddly moving. Her own people, farmers, had similar rituals in which you offered the gods household objects like cups, bits of clothing, farm tools like ploughs. You placed them in gaps, like ditches and doorways and river banks-places between worlds, where reality came unstuck. These were sacrifices to the gods, pleas for the continuing cycle of the seasons-and, today, pleas for victory and honour in war. And as he destroyed his iron weapons Caratacus built on a still more ancient ritual yet. It was the closure of a circle of life, for some believed that metal, born in fire, was alive, and that it was fitting that it should at last 'die' in water.

But Agrippina saw that among the gifts being offered to the river were Roman goods: Samian crockery, finely worked Gallic daggers and swords, even coins no doubt adorned with the invading Emperor's head. Even in this most sacred of British rituals, she thought, the Romans had already gained a foothold.

A runner approached Togodumnus, evidently bearing bad news. The prince swore, hurled away the last of his offerings, and stomped out of the water. His brother, Caratacus, continued with his patient ceremony.

Cunedda murmured, 'Togodumnus may pay for that. It doesn't do to turn your back on the gods.'

'Probably he's been told that the Dobunni have laid down their arms to the Romans,' Braint said laconically.

Nectovelin snapped, 'Gods, woman! If you were Greek I'd call you an oracle.'

Braint shrugged. 'I just listen to what people say.'

Cunedda asked Nectovelin, 'If things go badly today, what will become of everybody-the old people, the women and the children?'

Nectovelin grunted. 'The Romans haven't crossed an Ocean to be merciful. They'll be looking to strike a blow that will resound throughout the island. We may still be able to stop them doing that, even without the Dobunni. But it's in the hands of the gods.'

Agrippina asked softly, 'But, Nectovelin, your Prophecy-has it no news of what will happen today?'

He laid his fist over the chain mail covering his chest. 'The parchment is brief,' he said. 'Just a few lines. You can't expect it to list every little thing that will ever happen.'

'This isn't some "little thing", cousin!'

Nectovelin glared at her. 'No bit of parchment is going to help us here. Only iron and blood will shape our future now. Drop it, Agrippina.'

They were interrupted by cries of anger, coming from far off to the rear of the roughly assembled mass of Britons. Caratacus, his boots still wet, went running towards the commotion with a group of his allies, their swords already drawn.

Braint hopped onto a storm-smashed tree stump to see better. 'It's the chariots,' she called. 'Somebody's having a go at the horses.'

Nectovelin yelled, 'The Batavians!'

Agrippina asked, 'Who?'

He drew his sword. "Pina, find somewhere safe, and stay there. Braint-come on, you old boot, we've a few Roman skulls to crack before supper.' And he ran off, pushing through the jostling crowd of old women, children, goats and sheep.

'So it begins,' Cunedda said. With a last helpless glance back at Agrippina he followed Nectovelin.

Vespasian found his brother in the dark. The two of them met on horseback in a pocket of forest, close enough to the river for them to hear its murmur. They were alone save for their immediate staff officers, and a few burly legionaries as guards.

And, all around them in the blackness, more than ten thousand men were crossing the water.

'It's good fortune it's so dark,' Sabinus whispered to his brother.

'Yes.' So it was, though it was no accident that the night was moonless; the campaign's planning had taken the lunar phases into account. 'But I'm getting the feeling that even had we attempted the crossing in broad daylight the Britons might still not have spotted us.'

'It's hard to credit, isn't it? Wouldn't you post at least a few spies? It's not as if we've tried to conceal ourselves.'

Vespasian shrugged, his armour rustling as its banded plates scraped. 'I have a feeling these barbarians think it dishonourable to sneak around in the dark.'

'And it is more honourable to waste your life needlessly? Well, by this time tomorrow many of them will be able to debate the point with their gods. Come. Let's see how the crossing is going.'

They turned their horses' heads. A staff officer on foot led Vespasian's horse down the track cut out by the scouts earlier, and Sabinus's followed.

Flavius Sabinus, a few years older than Vespasian, had gone ahead of his brother into the army. His progress had been slower, and at one point Sabinus had actually served as staff officer to Vespasian. It had been a situation fraught with problems of rivalry, even though the brothers had always got along well. Thanks to Vespasian's links with Narcissus, though, Sabinus had now been elevated to an equal rank with his brother, and headed a legion of his own on this British adventure. And, as Vespasian had always known he would, Sabinus was proving effective in the field.

Certainly everything had gone well so far. The British had done nothing but sit on the bank opposite the marching camp, waiting for the Romans to hurl themselves on their rusty iron swords. Aulus Plautius's cold calculations concerning the minds of the British leaders seemed to be working out like a Greek mathematician's theorem, Vespasian thought-a simile he must remember for Narcissus and his letters to Claudius.

Meanwhile all eight of Plautius's cohorts of Batavians had slipped across the river, downstream of the marching camp. The Batavians were among the most useful of auxiliary troops, Vespasian had always thought, for they were specially trained to swim across even major rivers in full battle gear.

And, after shaking themselves dry like dogs, the Batavians had fallen on the rear of the British lines. Their purpose was to disable the British chariots.

The chariots had surprised Caesar when he had come across them a century before. They were terrifyingly fast, and would bear down on you with their occupants screaming and hurling their javelins. Even the noise of their wheels was enough to panic men and horses alike. The enemy could use the chariots as a weapon in themselves, and as a way to deliver his best troops to where they would be most effective. For Caesar the chariots were a nightmare from legends of the Trojan wars, and he had had trouble countering these fluid and mobile forces with his stolid legionaries. Even his cavalry had been put under threat.