Magnus whipped the mules continuously as they struggled across one of the two northern gaps in the trench- and breastwork left by the Parthians for the passage of their cavalry; Vespasian held on tightly as the vehicle rocked on the uneven ground. Smoke from cooking fires wafted about carrying the burnt odours of the conscripts’ hastily abandoned midday meals still in pots over the glowing wood. The booming of the Parthian war drum continued, increasing fractionally with every few beats as the massive horses accelerated slowly under their enormous burdens, their great hearts working at almost full capacity even though they were travelling at little faster than a quick walk; soon they would break into a trot for the very last dozen or so paces.
As the horse archers continued their massed but ineffectual volleys, Vespasian looked across at the advancing cataphracts, hundreds of them in two ranks, their armour shining in the sun and their banners fluttering over their heads, and marvelled that such a beauteous sight could be so deadly. The sun blazing down on them made the slow-moving wall of burnished metal seem that it was crowned in golden flame.
Flame? Fire?
Vespasian started; the wagon had cleared the earthworks and was now passing through the few artillery pieces on this side of the town. He glanced along the line of machines; there were at least two onagers. ‘Magnus! Pull over. Now!’
Magnus steered the wagon off the track and slowed, just ten paces from the bridge; the centurion in charge of the detail manning it signalled at them to press on but was ignored. Vespasian jumped off and ran to the nearest onager; and there he saw them: stacks of earthenware pots, one foot in diameter, with rags protruding from their wax-sealed tops.
Naphtha.
The war drum’s tempo increased. He looked back; hard up against the breastwork protecting the front of the abandoned trenches, the auxiliaries’ extreme left flank was just fifty paces away; the arrows had stopped beating down on their feathered shields for the cataphracts were finally at the trot and almost upon them.
‘Magnus! Hormus! Help me with these and bring the lads on the bridge with you.’ He picked up two pots and held one underneath each arm; he had expected to struggle but, surprisingly, they were not too heavy.
Magnus came barrelling over with the auxiliary centurion and his eight men.
‘Two each!’ Vespasian shouted at the men. ‘And then follow me as fast as you can. Hormus, bring burning branches from the cooking fires in the trenches.’
A mighty shout rose to the sky drowning even the pounding of the war drum; Vespasian did not need to look to know that the Parthian cavalry had collided with Mannius’ cohort. It was now just a matter of time.
Vespasian led his scratch incendiary unit at a lung-burning pace back across the siege lines directly to where the uneven cataphract-versus-infantry battle abutted them. He scrambled up the edge of the final earthwork, his arms cradling the Naphtha pots, struggling for balance and dislodging loose soil that tumbled down into Magnus’ face behind him. His head cleared the top of the defence and he looked along the length of Mannius’ cohort’s line, all the way to the city walls, a bowshot distant. And it was ragged, beset by armoured killers mounted upon beasts almost impervious to the weapons being wielded against them. With their horses pressing their huge bulk against the cohort’s front rank, pushing them down and back with cracked skulls and broken limbs, the Parthian troopers used their far-reaching kontoi to stab razor-edged points down into the faces of desperate auxiliaries in the second and third ranks, preventing them from using their weight in support of their comrades before them. Screams rent the air as eyes were pierced and throats were gouged; dying men dispersed sprays and mists of blood with their final explosive breaths as the juggernaut of cataphract cavalry pushed into the Roman infantry with the ease of a voyage-weary sailor penetrating a dockside whore. Javelins, swords and knives could not halt them, but Vespasian held in his hands the only weapon that would: fire.
Kneeling, he set down one of his pots. ‘Hormus! Bring the brands.’
The slave clambered up the bank with three thick sticks with red-glowing ends.
Without thinking of the dangers or whether he was doing it correctly, Vespasian proffered the Naphtha. ‘Light it!’
Hormus touched the glowing end of the brand to the trailing rag; it smouldered for a moment and then flashed alight as if impregnated by some accelerant, shocking Vespasian. Panicked by the rapidity of the fuse’s burning, Vespasian leapt to his feet and brought the pot, two-handed, behind his head, bending his back and legs, and then levered it forward with the pressure of his whole body unfurling behind it. The pot soared along the Parthian line to crash down onto the unarmoured rump of a front rank horse, twenty paces away, splintering into jagged shards and spilling a viscous brown liquid over the beasts and troopers close by; but it was virtually unnoticed in the chaos of battle as it did no more than that.