Xanthippus arrived with Epikleos and Cimon, clambering up with ease from the small boats alongside. It was hard to imagine the first time Themistocles had seen Xanthippus heave himself on board. He moved rather better than he had that day.

Themistocles waited until his men had brought cups of honey and wine, warmed on the brazier amidships. The morning was cold and they sipped with pleasure, tasting cloves and cinnamon. To a man, they watched the coast, where the Persian army was tramping south through the pass of Thermopylae.

Themistocles too watched the slow passage of regiments. The great army of Persia was a vast enterprise. The mere act of passing through a single spot and assembling on the plain beyond would take days. He could not see an end to them as they stretched back over the plains north.

He had known no small force could hold against them, not even the men of Sparta. They were not gods, to stand immune before spears and arrows, to defy soldiers who stood like stars in the night sky. And yet … the days had passed and somehow, each morning, there they were. Leonidas had kept his word, Themistocles thought.

‘We have all lost friends,’ Themistocles said, his voice low and hoarse after days of shouting orders. ‘None of us knew how many the king of Persia could put in the field, at sea, on land. From the first moment I saw this fleet, I thought, “How can we ever stop so many? How can we win?” I took heart from you – from Xanthippus, from Cimon, from Eurybiades …’ One by one, he named them all, men of Megara, Chalcis, Arcadia, down to the captain from Cythnos who had been able to pledge just one ship. It had survived a glancing blow from a Persian ram. Rough repairs and men baling seawater from below at all hours had kept it afloat. It still held its place in the line, after days of fighting.

‘You are Greeks,’ Themistocles went on with a smile, ‘so you did not despair. You looked at the narrow strait and the Persian ships and you chose this place to stand in their way, with me.’

He looked from man to man and saw only pride amidst the weariness. They had not been broken, not yet.

‘I did not intend at first,’ Themistocles went on, ‘to hold the line, to fight and ram with such ferocity, to risk everything just to hold them here. It was the example of Leonidas that changed our purpose, the news that the army needed time to come out.’

He paused and dipped his head, almost as if in prayer.

He did not say aloud that Aristides and the hoplites of Athens had been ready in the field for three days. They could not move without the Spartans and the men of Corinth and all the rest, that was the truth of it. Not against such a host. Not if they wanted to have a chance. No one alive had ever seen so many soldiers marching. Themistocles shook his head, realising his thoughts were drifting.