All the Persians began to point. The king was hard to miss. His green-bronze armour and his superb helmet shouted his presence. A messenger dashed back from the forward Persian troops, and they began to form.

We hit the ford. Our horses raised a curtain of spray and Alexander wasn’t slowing, so I dug my heels into Poseidon and hung on. Poseidon doesn’t love water.

A Persian – a noble in a bronze peaked helmet and a magnificent scarlet saddle – hurtled across our front on a big Nisean horse, moving like a grey streak, and he threw his javelin at the king, and Alexander caught it in the air with his own spear and parried it – a fine feat. Men cheered all along the faces of the wedge.

We started up the far bank. There were fifty Persians there, all throwing their spears, but none of them abided our onset, and they broke before us, and we were across.

Yet as soon as we were up the far bank, I could see that we’d charged into a nest of angry bees. Cavalrymen were coming up from the south and the east – even from the north – as far as the eye could see.

Alexander laughed. It was a mad laugh. He turned and his eyes glittered and his face was white, his cheeks and lips red as blood, and he looked like a dramatic mask – or like a god.

‘I think we have their attention!’ he shouted, and pointed the tip of the wedge at the nearest formed enemy body, two hundred Phrygian horse preparing to charge us. He raised his spear. ‘Ready, Hetaeroi? Charge!’ he roared, and my trumpeter picked up his command and sang it out.

The head of the wedge turned less than an eighth part of a circle, and then we were pounding forward up a slight incline, and the Phrygians came down at us with their longer spears. Their files spread as they charged, so that just before impact you could see the sunset between their men.

Alexander did his job as ‘wedge leader’ perfectly, taking the point of the wedge into the widest gap between enemy files – and he ducked the first enemy lance, a beautiful piece of horsemanship, perfectly judged, so that the lance-point passed a hand’s breadth over his back, and then he rose and his spear took the Phrygian on his right just below the throat – killing him and ripping him from his horse in one movement. The king’s spear snapped from the impact, and Alexander swung the butt of the spear into the next lance, parrying it off to his left across his horse’s head and then cutting back with his whole weight behind the staff – thunk, into the head of the second man on the left, and the man collapsed from the saddle – the king dropped his spear haft and unsheathed his sword, his body flat along the neck of his horse to evade the third lance . . .

It was beautiful. It made my heart ache to watch him.

And then I was fighting.

I was on the left, and the king had left the front-left man for me – I parried his spear with mine and ran my spearhead along his shaft, so that it slammed into his thorax and he was gone. I kept the spear, turned it and caught the next man with the butt close in – a clumsier blow than the king’s, but my man fell too. My horse’s haunches bunched and expanded and I was into my third man – Poseidon hit his horse, breast to breast, and knocked it to the ground, and Amyntas son of Amyntas struck me from behind – these things happen in a melee – and we got tangled, and the wedge was slowing – but the king was still pushing ahead, and I put my heels into Poseidon despite the ringing in my ears. I pushed forward into the press – the Phrygians were thickening like lentil soup in the pot, because another squadron had thrown themselves into the fight.

The king had three of them around him. In the glance I got, I saw him thrust his sword into one exposed side, and then, quick as a cat, draw back and flick a cut at the second and carry it around to the third.

He was like a god.

But he needed help.

Poseidon did his bit, pushing forward with heavy, massive, powerful surges from his hindquarters, so that I seemed to be rowing forward.

We were suddenly so close to the Phrygians that we were no longer threading between their files – now we were pushing in close, knee to knee, face to face, horse against horse, and now the horses began to fight each other, and I had to keep my knees all but locked and hang on with my arms to stay with my mount, because he was kicking, biting and pushing.

Hipposthismos, I remember thinking, in that way that your brain wanders off in moments of critical danger. Blows hit me – Persian spears – I got a slash across the top of my thigh, below the line of my tassets, and my bridle hand took its usual abuse – that’s why it looks the way it does, eh?

Othismos is the pushing and shoving and vicious infighting of the closest-packed melee. So you can guess—hipposthismos is the mounted version.

I came up against an officer – a high officer, with superb embroidery on his cloak and a sword with a hilt of gold – a sword I got to know very well, because he cut at my head, and I parried – sword to sword. Our blades cut into each other – that’s why you don’t use a sword to parry, lad! – and we bound up, and our horses pressed in, and there we were in a pushing match, hilts in front of our noses, legs crushed together, and I could smell his breath – and he mine.

I reckon he was a good officer, because as we struggled, he looked past me – trying to figure out, as I was, what in Hades was happening in the melee.

I dropped my reins, reached across my body with my left hand, put it under his right elbow and pushed – he twisted to keep his balance and his seat, and I got my hilt free and punched him with it . . .

And he was gone in the melee, and I was almost to the king. A blow rang off my backplate – I assume my erstwhile opponent backcut at me as the melee carried us apart – but it did me no damage, and I was almost there.

I had two or three heartbeats to look around – an eddy in the fight – and the Persians were coming at us from every side.

Alexander was putting Persians into the dust with almost every blow, but some of the feline grace was gone from his back and hips as he rode. Grace is the first thing to go as a man tires – we start to make slightly larger motions with the arms, the pelvis – anything to help the muscles work. Alexander was showing the very earliest sign of fatigue.

I got up to him as he caught a Persian spear in his bridle hand, pulled it from its owner’s grip and stabbed him with the butt-spike – all in a heartbeat.

My sword was bent. I hadn’t noticed it, but my fine Keltoi long sword was bent from the pushing match with the Persian officer, and it had a deep nick – almost a gouge – in the thick metal near the hilt.

I rang it off a Phrygian’s helmet, and it snapped.

‘Where is Philotas?’ Alexander asked, his tone almost conversational.

Here’s one of the differences between a normal, intelligent Macedonian and Alexander. I’d forgotten that Philotas existed. I was busy fighting for my life – Philotas was on a different plane of existence.

Alexander pulled on his reins and our horses lined up, head to head. But the Phrygians were done – they weren’t running yet, but they were falling back, riding clear of the melee or simply getting shy of combat.

Cleitus came up on Alexander’s left side.

He looked across at me, ignoring the king. ‘We need to get him out of here,’ he said.

I looked over my shoulder. We had Medes – or Persians – behind us, between us and the river – I could see their high hats and their bows.

And their arrows. Arrows were falling on the rear ranks of the wedge, and horses were screaming.

I think that until then we’d lost very few men, if any. We had good armour and excellent helmets – far better than the Phrygians or the Medes. And our horses were big – as big as theirs, if not as good as the Niseans. Our men were better trained in arms – the Persians don’t wrestle, and that’s a terrible disadvantage in a cavalry melee.