The air seemed full of arrows. Ferox leaned to one side to see down and felt the air snap as one flicked by where he had been a moment before. Another buried itself deep into the rail of the parapet, flinging up a big splinter. It was shorter than most, and he remembered facing such bows before. They were almost like little ballistae, from some old design he had heard was Greek, making it possible for one man to carry and shoot, but delivering more force over a short range than any ordinary bow.

Ferox reached for the shield he had brought and left leaning against the parapet. Yet he needed to see and could not simply cover himself. The Romans were sending back as many or more missiles than came in, so that there was a storm of arrows, spears and stones of the sort poets described even if few of them had ever seen such a thing.

The scorpio beside him slammed forward again, spitting a bolt which created another gap in the shields.

‘Got the bastard!’ Julius said again.

Without needing to be ordered, the defenders were lobbing stones or shooting arrows at whoever came closest. There were a few bodies at the foot of the wall, and more on the lip of the inner ditch, but still the Dacians came and still they screamed. Four carrying a long ladder were at the outer ditch when an arrow hit one on the leg. The three staggered on, down into the ditch, slipping and dropping the ladder, but others ran to them and they were hauling it up the other bank and down into the second ditch. A volley of stones and javelins hit them as they came up again, leaving the ladder dropped just at the foot of the rampart, with two dead or dying men around it and the rest, bruised and bloodied, back in the shelter of the ditch.

‘Got the bastard!’ Julius started cranking the slide back ready to shoot again.

Ferox saw or sensed something coming and lifted his shield in time to cover his face as a point burst through the layers of wood and calfskin on both sides. It stuck there, lacking the force to go further, even though he had swayed back with the impact. He guessed that it was from one of the special bows, and wondered whether to try and spot the men with these and use the scorpiones to pick each man off one by one.

For the moment, the raw power of the engines’ bolts had shattered the column coming up the road, leaving a debris of dead men as the rest retreated, like seaweed thrown onto a beach by the waves. Yet a third group was mustering on the edge of the canabae, swollen by the survivors of the earlier attacks. Someone was blowing a carnyx, one of the high bronze trumpets used by many tribes in many lands including Britannia and beside him there was a warrior who was surely a leader shouting and gesturing at the men.