Xerxes led the way to the main chamber below. Its existence gave his flagship a broader beam than all the others and separated his banks of rowers. The partitions of his cabin had been knocked down and cleared for the meeting of captains, but the long room retained a faint scent of damp as well as rose, musk and narcissus.

The table had been bolted to the floor so as not to shift in rough seas. The captains and senior officers had to edge along the sides to take their places and then sit at his order on the chairs made ready for them. Forty of them had come at his command. They smelled of salt and sweat and seaweed, Xerxes realised, though Artemisia bore some floral scent in addition that he could not recognise. She watched him closely, he noticed, judging him. It might have been infuriating in his court, but there, he felt his jaw jut and his determination grow.

‘Gentlemen … Your Majesty,’ he said. The words felt odd in his mouth. At least Artemisia spoke the language of his fathers. Some of the Greeks who had come to offer dust and water needed translators to stand by them and whisper. They were always a step behind, which irritated Xerxes. No one else would dare speak over him.

‘You may examine my maps before you leave, those of you who do not know this coast. We have anchored within the shelter of the island of Sciathos. To the west, there is a strait of calm water that leads inland, then turns all the way south, past Marathon, around the headland and there, to Athens. Mardonius? Report on the progress of our army.’

The general rose to his feet, so that all the rest turned to him, Greek and Persian alike.

‘Gentlemen … my lady. There is a range of mountains ahead of us that we should reach by tomorrow afternoon. One more march will put us there – as you come west along the strait. By the time you turn south, we should be through. We are looking for local scouts now, who know the area.’

‘May we see the map?’ one of the other captains asked.

To Xerxes’ irritation, the man spoke in Greek, but his cabin servants still moved, accepting his authority. The king forced himself to remember his father. Whatever hatred he felt towards the Greeks had to be smothered when it came to those who had asked to be allies. Most of them still hid from him, quaking in their cities and just hoping to survive the great invasion. At least these men – and one queen – had come to serve alongside! Xerxes had accepted dust and water from the hand of Artemisia herself, though her ships were better proof of her oath. He glanced at her again, wondering if she was younger than him. Her skin was as delicately flushed as any young woman, but she painted her eyes in kohl, so that it was hard to tell. Xerxes found himself looking away as the group leaned over the map, in awe of something that had cost more gold than they would see in a lifetime. It was the labour of years by expert cartographers and sailors, roaming that coast and taking note of every island and fresh spring. Only the land was blank, or marked with a few vague lines. His father had commissioned the thing at huge expense, before Marathon.