On either side of him legionaries and Celts were locked in a bitter and merciless struggle. The collapse of the Roman formation meant that both sides were pressed together in a tight pack where slashing weapons were useless and the short swords of the legions came into their own. The Britons knew they were outclassed and now punched and clawed at the Romans, fingers and fists scrabbling for purchase on any unprotected Roman flesh. With a shrill scream a young warrior hurled himself upon Cato, one hand clenched round the wrist of his sword arm, the other groping for his throat. For an instant Cato panicked, his muscles frozen in helpess terror, then the instinct for self-preservation made him release his grip on the shield, ball his spare hand into a fist and smash it into the cheek of the enemy warrior. The man just blinked and continued in his fanatical effort to throttle the Roman centurion. Cato tried once more, with no effect, then dropped his hand to the dagger at his waist. Snatching it out, he thrust it up and forwards, into the stomach of his attacker. The young man’s look of hatred turned into one of surprise and pain. Cato thrust again with all his remaining strength, and felt his dagger rip sideways, and a sudden warm gush over his hand and forearm as the enemy went limp and slid away, but was still held up by the press of bodies around him.

‘Run for it!’ Cato shouted to the surviving men of his century. ‘Run!’

There was a loosening of the mêlée as the legionaries backed away, or simply turned and dashed for the small opening in the crudely constructed gateway. It was now a running battle, with Romans slashing around them as they ran for safety and the Britons worrying them like hunting dogs trying to bring down their prey. Cato made for the standard-bearer and was relieved to see Septimus already at the bearer’s side, hacking away at any Britons that dared to venture too close. Then the three of them, back to back, shuffled towards the gate, up the last few feet of the narrow ramp leading between the enfilading defences. Above them their comrades dare not shower the attackers with their javelins for fear of hitting their own men.

Cato sensed the gatepost at his shoulder and shoved the bearer inside. ‘You too, Optio!’

‘Sir!’ Septimus began to protest, but Cato cut him short. ‘That’s an order.’