‘Better a fiery death in glory than a long life and a dull end,’ he declaimed as she led him through the curtain.

Damn, that was the best exit line I’ve ever heard, and I still laugh to think of it.

And when most of the actors were gone, or asleep in the corners, and it was just Kineas and Thaïs and Diodorus and Niceas and, of all people, my Polystratus, sitting over a last cup of wine, Kineas got up (unsteadily) and raised his cup.

‘Let’s drink together – an oath to the gods, to remain friends always. We will conquer Asia together. Let’s drink on it.’

We all rose – no one mocked the notion – and we all drank, even Thaïs. Nearchus was there, and young Cleomenes, and Heron, and Laodon. The cup passed – we all drank.

‘I can feel the gods,’ Kineas said, in a strange voice – but no one laughed because, as Thaïs said afterwards, we could all feel them.

And indeed, I sometimes think that the gods are as drawn to laughter and happy drunkenness as they are to battlefields and childbirth – and if that is true, we must have had all Olympus by us that night.

The night before we were due to march, Olympias summoned Alexander to her. I was there when the summons came, and despite his love for her and his endless patience with her, he rolled his eyes like any teenage boy summoned by his mother. He was in a state of exaltation that was nearly dangerous – he was about to achieve the entire ambition of his life.

We shouted for him to go and come back, and he waved a hand, pressed Hephaestion to stay and keep the couch warm, and left us. I remember because I passed the time of the king’s absence by playing Polis with Cleitus, and I won, and Cleitus, who was drunk and in a mood, punched me, meaning only to give me a tap, but he hit me so hard that I had a bruise for a week, and only Nearchus kept me from hitting him back, or worse.

Alexander came back into the ruckus, and he was white, his lips were almost indistinct and he didn’t notice the tension – which dissipated instantly, because no little quarrel was as important as the king’s anger. He was angry – or worse.

In fact, he looked terrified.

Hephaestion took a look at him and ordered us all to bed. And we went – Alexander in one of his moods could be deadly.

Of course, nowadays, everyone knows what his mother told him – that he was not the son of Philip, but the son of Zeus Ammon, and that she had been made pregnant by the god.

It’s easy to be incredulous and cynical. But in Macedon, we take gods seriously. We’re not like fucking Athenians, who think the gods are so far away that they don’t exist. In Macedon, we credulous barbarians always believe that the gods are present in daily affairs. And every noble in Macedon is the direct descendant of one of the gods.

And Olympias was no madwoman. Say what you will of her – her only addiction was power, and she played the game better than almost anyone in her generation. She was brilliant, cunning and beautiful, and utterly without scruple, except when it came to defending her son. She used murder, the army and her body with equal facility. She could reason, cajole, threaten, seduce or eliminate. But she was not mad, and if she told Alexander that he was born of a god, it’s best not to dismiss the idea out of hand. Certainly Thaïs – a cynical Athenian hetaera – accepted the story at face value. Priests at Delphi accepted it. Aegyptian priests accepted it. It is fashionable now to say that Alexander was not half a god – merely a man. Very well. But I knew him, and I say that there was something beyond the human – something inestimably greater, and yet sometimes less than human, in him.

Regardless, Alexander believed her. The cynic might say that he had to – that having participated in the murder of Philip, he needed to be told that he was not Philip’s son. Perhaps – but again, Alexander was never so simple, and I never saw him betray the least guilt about Philip.

What I can say is that from that night, he never again referred to Philip as ‘my father’. And that, in turn, had consequences that none of us could have foreseen.

Next morning, we marched for Asia. We marched with forty thousand men, and we had our supplies sitting ready in magazines all the way down to the Asian shores, and Alexander was determined to march along the same route that Xerxes had used. And we did.

We made excellent time, passing from Amphilopolis along the coast route to Sestos in the Chersonese. But the tensions grew every day, and they made the trip harder and harder.

It was all but open conflict between the king and Parmenio.

Parmenio issued orders to the army without any reference to the king. Parmenio summoned army councils and sent the king an invitation. Parmenio changed the route of the march and the intended crossing-point without speaking to the king. Alexander had intended for the army to cross at Sigeon, near Troy, which was in our hands and had a protected port.

I had my own reason for anger. In the first three days it became increasingly clear that I was notto have command of the Psiloi. Attalus – another Attalus, one of Philip’s men – received the command from Parmenio. I received a verbal message from Alectus, asking me to meet him, and he insisted that we meet outside the camp.

It was a difficult meeting – Alectus got to tell me I’d been replaced, and I didn’t know how to respond – I lashed out at Alectus instead of saving my ire for the man responsible.

I went straight to the king, and pushed through his companions – as was my right – to where he was donning armour.

‘I have been deprived of my brigade,’ I said.

Alexander was just being put into his thorax. Hephaestion was holding it open for him, and he was pulling his heavy wool chiton into folds to pad the metal. ‘Good morning to you, too, son of Lagus,’ he said.

‘Parmenio has given my brigade to another of his old men,’ I said.

Alexander nodded. ‘I’m sorry,’ he said.

I remember the feeling of horror I had as I realised that the king was not going to doanything. Either he could not or he would not.

I was reminded of Pausanias, somehow.

‘I’m sorry,’ he said again. Quietly, he added, ‘There’s nothing I can do. We are all young and inexperienced.’

I stormed out of his presence without asking permission, and I was allowed to go without rebuke.

I considered going home.

Thaïs checked me. ‘Sooner or later, Parmenio intends to kill him,’ she said. ‘Probably on campaign. Will you just ride off and leave him? He’ll die without you.’

It was an interesting role reversal, and it did our relationship a world of good. At Thebes, it had been I talking her into staying with the army – with Macedon. Now the situation was reversed, even if the minutiae were wildly different.

‘I’m staying,’ she said that night, with utter finality. ‘Go home if you like. I have sacrificed everything to be there when the king marches into Asia.’

Once I would have reacted to that. I would have attacked her for the suggestion that she had sacrificed everything. But I knew better, now.

She came and put her arms around me. ‘He’ll die without you,’ she said again. ‘Nor will I be very happy.’

She was in a position to know. With Parmenio in complete control of the army and the scout forces, Thaïs was the effective chief of the king’s intelligence service.

I continued to have charge of the Military Journal and attached functions, and what rankled me – perhaps more than anything else – was that Parmenio was unfailingly polite and cheerful, and acted as if nothing had happened. He insisted that his officers supply me with their daily reports, so that the Journal ran more smoothly than ever before. Even officers like Amyntas, who affected to despise me, were quick to send their adjutants to report on numbers and effectives and men sick, ground covered, and all the details that made war possible.