It took a moment for the men to respond, so rapt were they in the fate of their comrade.

‘Ready your bloody javelins!’ Cato roared at them.

This time his men hefted their weapons, stepped forward two paces and swung their throwing arms back. Decimus saw the movement and faltered briefly before he hurled himself towards the line of shields. Right behind him the Britons whooped with cruel glee as they realised that there was no chance now that their prey would escape them, still thirty paces from his comrades.

‘Decimus!’ Cato shouted to him. ‘Drop down!’

Realisation of the centurion’s intention suddenly dawned in the legionary’s terrified expression and he threw himself forward on to the track, rolled a short distance to one side and covered his body with his shield as best he could as Cato shouted an order to the front rank.

‘Javelins . . . loose!’

There was a chorus of explosive grunts and ten dark shafts curved through the air, passing over Decimus and striking the horsemen immediately behind him with a series of dull thuds as the sharp points punched into the flesh of men and beasts alike. At once the air was split by the agonised whinnies of two mounts and the snorts from the others as they tried to swerve away from the stricken horses. One man was down, pierced clean through his breast, and he crashed down on top of Decimus, splintering the javelin shaft with a loud crack. He quivered for an instant, then died.

The impetus of the charge had been broken, and the enemy milled round the stricken tangle of the writhing, wounded horses. Decimus saw his chance at once, heaved the body off his shield, scrambled to his feet and threw himself towards the front rank of the century, abandoning his shield.

‘Come on!’ Cato desperately beckoned to him. ‘Make a gap!’

Two of the men shuffled aside and Decimus made for the space that had appeared between their shields. Just as he reached his comrades, Cato glimpsed something blur through the air behind Decimus and then the legionary tumbled forward into the Roman ranks with a cry of pain. Cato pushed his way over to Decimus and kneeled down. The shaft of a light javelin pierced through the back of his leg, just above the top of his boot, and blood welled up where the thin iron head had entered the flesh.

‘Shit! That hurts!’ Decimus hissed through clenched teeth.

Glancing up, Cato saw that the horsemen had withdrawn a short distance down the track and were re-forming, ready to charge again.

Septimus loomed over them, glanced at the javelin and nodded to Cato. ‘Hold him!’