The First Cohort rounded the corner of the final dogleg and began to pass between a bastion and the main gate. This was the most dangerous moment of the assault. The men were under fire from two sides and could not begin to deploy the ram against the gate until the bastion was taken. The senior centurion knew his job, and in calm, measured tones gave the order for the First Century of the cohort to break away from the testudo. The men turned abruptly and scrambled up the steep slope to the bastion. The Durotriges who had survived the barrage of bolts threw themselves on their attackers, making the most of their height advantage. Several legionaries fell to their weapons, tumbling and slipping back down the slope. But there were too few of the enemy to hold off the Romans for long, and the vicious thrusting swords of the legionaries made short work of them.

As soon as the bastion had been cleared, men armed with compound bows scampered up and began pouring fire onto the defenders on the main gate, ducking down to string the next arrow behind the shields of the century who had won the bastion. The Durotriges redirected their missile fire onto the new threat, taking the pressure off the testudo standing at the base of the gate. Now the engineers moved up with the battering ram, and under cover of the testudo began a slow rhythmic assault on the stout wooden beams of the main gate.

The dull thud of the ram reached Vespasian's ears and his mind turned to Cato and his small party on the other side of the hill fort. They, too, would hear the ram, and start making their move.

Below the drainage gully on the other side of the hill fort, the pile of sewage and refuse suddenly came to life. Had there been a sentry on the palisade above, he might have had difficulty believing his eyes when a small party of what appeared to be Celtic warriors emerged from the foul-smelling heap and silently swarmed up either side of the gully, making for the wooden opening set into the palisade. While the engineers had been busy levelling the ground, a small party of legionaries, the best men of the former Sixth Century of the Fourth Cohort, had quietly made their way round the hill fort, under the command of their optio and the tall Iceni warrior they had been introduced to earlier that night. Naked, and daubed in the blue woad designs of the Celts, they were equipped with cavalry long swords, which might just pass for native weapons at a quick glance. Prasutagus had led them over the ramparts and through the staked trenches to the reeking mound of spoil. There, with silent expressions of disgust, they had hidden themselves amid the shit and slops, and waited, motionless, for the coming of dawn and the battering ram attack on the main gate.

At the first distant thump of the ram, Cato pushed aside the rotting deer carcass he had been hiding beneath and clambered on all fours up towards the wooden structure. With natural agility, Prasutagus scaled the far side of the gully, reminding Cato of an ape he had once seen at the games in Rome. Around them were the rest of the men Cato had selected, tough and mostly of Gaulish extraction, so that they stood a better chance of passing for Britons.

By the time they reached the top of the gully, the thudding from the ram had become a regular beat, sounding the death knell of the hill fort and its defenders. Cato pointed at the space under the opening and, as before, Prasutagus shifted his powerful frame into position. Cato clambered up, and cautiously looked over the rim into the hill fort's interior, by daylight this time. The plateau immediately to his front was deserted. Off to the right, beyond the giant figure of the wicker man, a dark mass of bodies was packed around the main gate, waiting to hurl themselves upon the First Cohort the moment the ram burst through the thick timbers of the gate. Among them were some black cloaks of the Druids and Cato smiled with satisfaction; the odds against him and his small party had lessened.

He pulled himself over the rim, and reached down for the hand of the next man. One by one they clambered through the opening and crawled to the side of the nearest animal pen. At last only Prasutagus remained, and Cato braced himself firmly against the timber frame of the platform before he reached his hands down to Prasutagus. The iceni warrior grabbed Cato's forearms and heaved himself up, transferring his grip to the rim of the opening as soon as he could.

'Are all the Iceni as heavy as you?' Cato gasped.

'No. My father – bigger than me.'

'Bloody glad you're on our side then.'

They scrambled over to the other men, and then Cato led them along the pens towards the Druid enclosure. At the last pen he signalled for his men to be still, and then slowly poked his head round the wattle panel, cursing softly at the sight of two Druids still guarding the gateway into the enclosure. They were squatting down and chewing on hunks of bread, apparently unconcerned by the desperate fight at the gate. Cato pulled his head back and motioned his men to stay down. They must keep out of sight until the main gate fell, and pray that the Druids had not already executed their hostages.

'This isn't going very well,' Vespasian grumbled, watching the distant battle in front of the gate. Most of the men on the bastion were down, and die British fire was concentrated on the legionaries massed by the gate. Already the ground was littered with red shields and the grey mail armour of the Romans.

'We could call them back, sir,' suggested Plinius. 'Lay down another barrage and try again.'

'No,' Vespasian replied curtly. Plinius looked at him, waiting for an explanation, but the legate remained silent. Any relaxing of the pressure on the front gate would put Cato and his men at risk. For all the legate knew, they might already be dead, but he had to assume their part of the plan was going ahead. Only Cato could save the hostages now. He must be given a chance. That meant the First Cohort had to remain in the killing ground outside the hill fort's gate. There was another reason for keeping them there. If he ordered them back down the rampart, they would lose more men on the way. Then, while the bolt throwers renewed their barrage, the survivors of the first assault would have to wait, knowing they had to face the perils of the attack all over again. Vespasian could well imagine what that might do to their fighting spirit. What they needed up there right now was encouragement, something to strengthen their resolve.

'Get my horse, and get another for the eagle-bearer.'

'You're not going up there, sir?' Plinius was shocked.

'Get the horses.'

While the mounts were fetched, Vespasian tightened the ties under his helmet. He looked at the eagle-bearer and was reassured by the man's easy composure, one of the key qualities looked for in men picked for the honour of carrying the eagle into battle. The horses were rushed to them by running slaves and the reins handed over. Vespasian and the eagle-bearer swung themselves up.

'Sir!' Plinius called out. 'If anything happens to you, what are your orders?'

'Why, to take the hill fort of course!'

With a swift kick of his heels Vespasian urged his horse towards the foot of the ramp, pounding across the open ground with the eagle-bearer just behind him, reins in one hand, the shaft of the standard clenched in the other. Up the ramp they galloped, swerving round at the first dogleg and on to the second ramp. Here lay the first Roman casualties, pierced by arrows or crushed by stones, their blood pooling on the track amid the feathered shafts that seemed to have sprung up from the soil. The wounded, seeing the horsemen approach, painfully hauled themselves to the side of the track, some of them managing to raise a cheer for the legate as he thundered past.