The first ranks hit trenches concealed with river rushes and loose soil. At full gallop, the horses went down hard, sending their riders flying. Some of them had their feet trapped in the stirrups and dislocated their legs as they were brought up short. The army of Jelaudin roared, but the Mongols recovered quickly. More than a hundred had fallen, but those who still lived curled into a ball and used their mounts as shelter as the ranks behind leapt over them. A few more fell as they misjudged the barrier of broken horses, but the line hardly slowed. No other army could have loosed a volley in the strip of land between the trenches and the enemy. The Mongols sent shafts as thick as flies into the enemy, knocking them back. As they reached the lines of swords, some of the warriors threw down their bows, while most took a moment to secure the weapon on a saddle hook, drawing a blade with the other hand. They did not consider the dead men they left behind at the trenches, only that they avenged them.

The roaring line hit Jelaudin’s soldiers at close to full speed, the weight and power of the horses as dangerous to a standing force as the blades themselves. The Mongols spent their mounts ruthlessly, using them as battering rams to break the lines apart.

Kachiun could see the curved blades of the Arabs swinging in flashes of sunlight as they resisted. His tumans had struck only a small part of the line and more than half of his men could not bring their weapons to bear. Instead, they sent arrows over their own ranks, the black shafts rising high to fall anywhere in the enemy host. They tore into the Arab force, but as Kachiun had been told, the enemy shields were well made and their discipline held. He saw shields raised high overhead, so that they formed a wall against the dropping shafts while the men sheltered safely underneath.

Jelaudin’s men fought with fury and discipline as they were forced back a step and then another, over their own dead. The Mongol charge lost its speed against their packed ranks and the curved swords still rose and fell in unison. Warriors were cut from the saddle and, to Kachiun’s horror, he saw his men pushed back as the Arabs surrounded any warrior in their midst, like islands in a sea.

The rest of Jelaudin’s army began to swing out against him. They had abandoned the safety of their position, but the advance was in order, rather than a mad rush. The far flank moved forward and Kachiun swore to himself. His column had cut into just one part of the enemy and he reached for the horn at his throat to counter this latest threat. When he blew the note, Khasar answered, pulling his men back with just a single order that flowed down the chain of command. Kachiun saw his questioning glance and pointed to the closing door of men that was swinging across the plain. Jelaudin’s men knew where the trenches lay and they stepped across them with barely a pause. In just moments, they would have encircled the Mongol tumans and then the killing would begin in earnest.

Khasar had ten thousand archers, each with a quiver of thirty arrows on his back. They formed up in the widest line they could make, though the leading edge was quickly sucked into the fighting on the wing. The rest bent their bows at those who marched towards them. Khasar dropped his arm and thousand of shafts bit the air, thumping into armour and men. Another volley followed on the instant and one more.

Kachiun shouted in frustration as he saw the Arab lines shudder. Hundreds of them fell, but they walked with shields high and merely grunted as they took the shots. Kachiun was exposed and for the first time he truly feared defeat.

He blew the horn again, a double note repeated that would send his men running. Those who were closest to him responded first, but the order spread like a ripple through the tumans. Khasar cried out in anger, but then he too turned his horse from the enemy and pulled back.

The Arab forces howled in triumph to see their enemy run. Thousands of them tried to cut down the Mongols riding away from them, racing after them with swords held ready for a vicious blow. Kachiun waited for the rest, making sure he did not ride so quickly that he left them all behind. The false withdrawal would have been easier against mounted men, where each rode alone in a wild frenzy of bloodlust.

Kachiun took a sharp breath when a new horn signal sounded across the plain. It was not one of his. To his amazement, he saw the running Arab lines stagger to a halt and turn back. Some gaudy prince among their line had blown the note and they gave up the chase on the instant. Kachiun had already been planning the point when he would turn and cut them to pieces, far from the protection of the ground they had prepared.

Instead, they re-formed where they had first stood and the tumans were left alone on the plain, panting and bloody in their frustration.

Only a few of the Arabs were too slow to respond and were cut down by Mongol warriors. The rest stood in solid ranks and bellowed insults, raising their swords and shields as if daring the Mongols to come and take them. Kachiun could see Khasar’s appalled expression as the two brothers met half a mile away from the battlefield.

‘Jelaudin,’ Khasar said, gasping for air. ‘That bastard knows us too well.’

Kachiun nodded grimly. The son of the shah had seen false retreats against his father and he had been ready. The Mongols had been made to look foolish as they ran from the enemy and he struggled to find the calm he needed.

The sun had moved astonishingly far during the fighting, so that early evening shadows leapt from him as he dismounted and tipped a waterskin to his mouth. There was time for another attack, but Jelaudin had out-thought him at every step and his confidence had been shattered. Khasar sensed his confusion and spoke again, needing his brother to start thinking.

‘What about taking up a position outside their lines tonight and sending arrows at them? It might draw them away from the hills at their back.’

Kachiun shook his head.

‘With no other threat, they would just gather under shields. The shafts would be wasted.’

‘Then what, brother? Leave them to their victory?’ Khasar asked. His eyes widened in shock as Kachiun did not reply. ‘You would let these dog-raping farmers have the day?’

‘Unless you have a better idea,’ Kachiun snapped.

Khasar gaped at him and both men looked up gratefully as Jelme rode up, covered in dust.

‘They are cut off from the river, at least,’ Jelme said. ‘Whatever supplies of water they have must run out eventually. We can wait them out.’

Khasar looked scornful at the idea.

‘I wish Tsubodai were here,’ he said. ‘He would not have us waiting for an enemy to die of thirst or old age.’

Kachiun grimaced, though he shared the same thought.

‘It comes down to this,’ he said. ‘No tricks or manoeuvres. Bows and swords alone against twice as many.’

‘That’s all you have?’ Khasar asked incredulously. ‘Genghis will have your thumbs for a plan like that. We’d lose more than half our men.’

‘We have never faced another one like this, Khasar, and we must win.’ He thought for a moment while the other two men watched him anxiously. ‘If they will not leave the position, we can approach slowly, clearing the ground as we go.’ He looked up and they saw his confidence return.

‘Archers to the front to keep them down and under their shields as we come in. Lancers behind them, ready to charge. Without the pits and stones, they are just an army of foot soldiers. We will cut them down.’ He glanced at the sun approaching the western hills and grimaced. ‘But it will not be today. We must wait for dawn. Have the men rest and eat and bind their wounds. Tomorrow will test us all, but we cannot fail in this place.’

When Khasar spoke, his voice held none of his usual mockery.