A horn blew, a harsh, high-pitched, reverberating call unlike any army trumpet. Something whipped through the air and slammed into his right thigh, driving through muscle and flesh and into the wood of the saddle. An instant later a second arrow hit his chest, piercing one of the tinned bronze plates. He was flung back hard against the horns at the rear of his saddle, gasping as the wind was knocked from him with the force of a swung hammer. A slim shaft almost three feet in length with white feathers on the end stuck out of his chest. There was a great dark stain spreading out from the arrow in his thigh, more blood welling from the wound in his chest and seeping out between the scales, and as he tried to breathe his spittle was red. The decurion slumped forward as two more arrows sliced through the air. A horse reared, screaming in agony and hoofs thrashing. The rider alongside was hit low in the throat, the long-pointed arrow spearing into the little gap between the broad cheek pieces and the top of his mail shirt, with a force so great that it lifted him up and out of the saddle. He fell, arms spread and spear and shield dropping from lifeless hands, blood jetting in a high fountain. There was a rattle as sling stones struck, blinding one of the horses and striking another man’s helmet with a dull thud.

An old soldier, grey-bearded and with an empty eye socket covered by a leather patch, took charge.

‘Back!’ he yelled at the driver. ‘Get back across and get going. We’ll protect you!’

The coachman nodded and pulled hard on one side of the reins, flicking his whip to turn the team.

‘Testudo!’ the old soldier shouted. ‘Testudo on me!’

The rearing horse was down, an arrow in its belly and a front leg broken by a stone. Its rider was underneath, and he cried out as the animal rolled over him, limbs thrashing, and then went silent. The man hit on the helmet swayed, was hit by another stone, this time in the face, smashing his nose, and fell to the ground in a clatter of armour and weapons.

‘On me!’ the veteran kept yelling. He had his horse facing the woods, at an angle as if to make it a barrier, and the other six men rode to stand in a line behind him. Their long oval shields were upright, covering the rider from shoulder to below the knee and because of the angle giving some protection to their horse. It was a drill they often practised and the Batavians formed up without having to think about what they were doing.