From the enemy barricades the great roaring battle cry went up again. But now the Roman horns were blowing the general advance, a discordant brassy braying. Castus saw Rogatianus and his men beginning to push forward towards the swampy water.
A little to the left, a fallen tree lay partially submerged, black with rot and old moss, but the jutting craggy branches offered some cover.
‘This way,’ Castus called quickly, gesturing to Flaccus, then scrambled down the slope towards the tree. When he turned he saw the standard-bearer coming after him, a loose array of men following. His boots slid in mud, then he was in water up to his knees. Already arrows were pocking the surface ahead of him, some of them smacking into the wet timber of the tree. Castus recoiled as a slingstone exploded off the trunk beside him, scattering flakes of bark. To his right, Rogatianus and his men were wading out into the flood, surging the water into dark brown froth, but their advance was already slowing under the rain of missiles.
Shouts from behind him, a trumpet cry and the sound of horses; Castus crouched beside the fallen tree and looked back, and the blood froze in his body.
Three riders, coming at the gallop down through the troop lines. Two wore the white cloaks of the Corps of Protectores, but the lead rider blazed in purple and gold.
‘Men of the Sixth Legion!’ the emperor cried as his champing horse circled before the trees. ‘Remember Eboracum! You were first to acclaim me then – who will follow me now?’
Without waiting for an answer, Constantine spurred his mount forward towards the water, the two bodyguards galloping after him. For a moment the troops were motionless, stunned, their faces blanched above their shields.
‘The emperor!’ Castus yelled, shoving himself away from the tree. ‘Protect the emperor!’
Water lashed and sprayed around the horses, brilliant in the sunlight. One of the Protectores went down at once, straight over his horse’s head as the animal stumbled and fell. Castus grabbed the standard-bearer and hauled him up beside him.
‘Wedge formation!’ he shouted, the words tearing his throat. ‘Form on me!’
Shield high above the water, he began to force his way out into the stream. Behind him men stumbled and staggered, bunching into a tight knot of shields. The water felt thick as oil, the bed soft sucking mud grabbing at their boots, and all around them was the whip and whine of arrows and slingshot.
The second bodyguard was down, his horse rearing back with an arrow in its breast and spilling the rider from the saddle. The animal tumbled, thrashing its hooves, and the surface of the water shattered into fountains of spray.
Castus kept his head low, concentrating only on pushing forward into the stream. The light was hot around him, and the muddy water dragged at the links of his mail – he was thigh deep, now waist deep, half swimming as he drove himself onward. Beneath his breath he muttered a constant prayer. When he risked a glance above the shield rim he saw Constantine, his big white horse foaming, poised in midstream with his sword raised towards the enemy and his stretched face crying defiant rage.
Then the horse shuddered, tried to rear and collapsed upon its haunches in the flood. Its chest was streaming with blood where it had run against one of the submerged stakes. Castus could hear the wild rage in the voices of his men, the fear-dispelling anger. Something caught at his ankles and he toppled forward, plunging face first into the water; a fist gripped the back of his mail and hauled him to his feet, and he surged forward again.
Constantine was down, arrows flickering around him as he tried to roll from the saddle of the dying horse. Brown water seethed, turning dark red with blood. Two arrows struck Castus’s shield in quick succession, and a slingstone cracked off his helmet, but he could feel the ground getting firmer beneath him, the slope of the bed rising.
Four more thrashing strides and he was beside the emperor, raising his shield above his head as the arrows lashed around them. Other men – his own men – slammed up around him.
‘Testudo!’ he could hear himself shouting, and the word was almost lost in the noise of the water and the frantic screams of the dying horse. Two men were knocked down by a flailing hoof, but the rest stayed firm. Shields rattled together into a ragged screen above the fallen man.
‘Modestus, Firmus,’ Castus ordered, ‘pull the emperor loose and carry him. We retreat to the bank.’
‘No, no,’ Constantine shouted. ‘Advance!’ His face was grey with pain and shock, his teeth clamped hard as the two soldiers dragged him from under the fallen horse.
‘Dominus! We need to pull back!’ Castus glanced down at the emperor, but even as he spoke he knew there was no turning now. Constantine seized Castus by the belt, hauling on it to drag himself free of the horse. His gilded cuirass streamed with blood and muddy scum.
Castus lowered his shield and peered over the rim; the enemy barricade was only a score of paces away, the enemy beginning to scramble across it and spill down the bank towards the stricken emperor. But there was another sound now, a regular snap and hiss from the forest behind and the air above. As he stared, Castus saw a warrior on the barricade transfixed by a ballista bolt. Arrows were falling among the advancing Bructeri. Roman archers had moved up to support the attack, and artillery too.
Over to the left, beyond Rogatianus’s men still trapped in midstream, Castus saw a solid wedge of legionaries forcing their way across the flood. At their head was Tribune Jovianus, his face a mask of blood as he screamed through broken teeth. With the defenders distracted by the emperor’s charge, the men at the barricade had thinned at that point – Jovianus was already halfway to the far bank, and the men behind him moved with a fierce discipline.
Dragging Modestus close, Castus yelled into his ear. ‘Take two men and get the emperor to safety. Cover him with your shields – don’t let him move forward again! Do it, whatever he says!’
Modestus nodded, slack-jawed but resolute, and Castus shoved him away.
‘Wedge!’ he called, striding forward again through the shallows. ‘Wedge formation – follow behind me!’
His men meshed behind him, pressing forward for the bank. Every step dragged a weight of soaked clothing and armour, the mud trawling off them as they moved. But they were together, shields locked and spears levelled, every man screaming his own hoarse cry as they stumbled up out of the water onto the bank.
Castus looked to his right, and saw Flaccus fall with an arrow in his face. He saw Diogenes snatch the standard from the bloodied water and raise it high.
He looked to his left and saw Jovianus and his men hurling themselves at the barricade, the bristle of spears raised against them, bare-chested men pelting slingshot and loosing arrows from a sword’s length away.
Up the slope, skidding and sliding on the wet earth and bloody grass. Something nicked his thigh, and pain lanced up into his hips as he saw the flung javelin skittering away. A body fell against him – Aelianus, dead eyes turned skywards – and he shoved it aside with his sword arm. Stumbling, he dropped to one knee and saw that his shield was fletched with half a dozen arrows; two of the vicious barbed heads had punched through the wood.
Over to the left the attack was faltering, men falling, others spilling back down towards the water. Through a fog of pain Castus watched the last of the soldiers scrambling up onto the barricade. He watched Jovianus shouldering his way between two Bructeri warriors, cutting and stabbing low on the brink of the fortification. He watched the spears dart out and cut at the tribune’s legs, a swinging club knock him down. Then they were on him, dragging him across the mesh of timber, stabbing him in the face and body with savage triumph.
Move, got to move… Castus dared not look back to see how many of his own men still lived. The pain rushed in waves through his whole body, and his right leg was streaming red. When he raised his hand an arrow skimmed across the back of it, slicing the skin, and for a moment he saw his own blood misting the air.