Towards the front of the column was a chariot. Standing on the platform, behind the driver, was Caratacus, bare-headed and bare-chested, with the huge gold torc around his muscular neck. One hand grasped the shaft of a great war spear, nearly twice as tall as the man himself. The other rested easily on the side rail of the chariot and despite the rutted surface of the track the native commander rode his vehicle with a superb sense of balance and self-confidence.

Caratacus raised his spear and thrust it towards the retreating Romans in a savage gesture of command. At once his warriors let out a huge roar and surged forward, swords and spears raised up and ready to strike. Septimus halted his men, closed up and shouted an order for them to unleash their javelins. It was a desperate measure and Cato wondered if the optio had let desperation overcome good sense. The effect of the collective volley in the confined space of the track would be devastating, but there would be no javelins left after that, only swords.

Septimus’ shouted commands were just audible above the din of the enemy. ‘Javelins . . . loose!’

A tattered dark veil lifted up from the legionaries, arced into the air and then lashed down on the natives. Their war cries faded for a moment, then the sound of the impact carried to Cato and his men: a rattling, thudding chorus that was quickly swallowed up by cries of pain and shouted curses. Septimus yelled at his men to continue falling back.

There was a brief respite while the Britons picked their way through their dead and injured littering the ground from which the dark shafts of javelins protruded at every angle. Then the battle cries picked up once again and the enemy raced forward. But the full impact of their mass charge had been broken by the volley and they hurled themselves individually upon the broad shields and glinting blades of the legionaries. The first few were cut down without difficulty and the men did not even break step as they continued towards Cato. Then, as warriors charged home as a mass, Septimus and his men slowed to a halt and were forced to fight to stay in formation. To fight for survival.

As more and more of the enemy piled into the mêlée the legionaries began to move towards Cato again, only this time they were not giving ground, they were being driven back. Watching them draw closer Cato knew that it was only a matter of time before Septimus lost so many men that the survivors would no longer be able to hold their formation. Then they would be broken and cut down. The leap-frog withdrawal of the sixth century would no longer be possible, Cato realised. Their only chance was to stay together now.