‘It is a wonder, Majesty,’ Mardonius said. His eyes darted back and forth as he drank in the scene. Xerxes nodded, pleased his general was using the perspective as he had intended.

‘I have reports of the food caches in Thrace,’ Mardonius added. ‘They came under attack by some local king there, but our soldiers fought them off and burned their villages.’

Xerxes waved that away. The problem of feeding such a host was one he could solve with sufficient will, wealth and slaves. The empire spread like spilled honey, infinitely slow but unstoppable, covering the world in sweetness. His marching columns had supplies waiting for them at a dozen places on the other side of the Hellespont. His ships had been landing men and equipment for over a year, with local agreements enforced with gold or slaughter. It had not mattered to him how it was done. His order had been enough.

‘Good. My father would be proud, I think.’

‘He would, Majesty. He is,’ Mardonius replied.

The man chose to drop to one knee and bow his head at the honour of speaking of the departed Great King. Xerxes smiled.

‘He will be,’ he corrected, after a time. ‘I will command the fleet, general. I will close down the sea to the Athenians, like a fishing net drawn along the coast. At the same time, you will take the army across the Hellespont and march west with us. I will meet you in the ashes of Athens and we will shake hands then. Do you have any other questions for me?’

Mardonius thought for a second, rubbing a hand through the thick blackness of his beard, where his lips showed red and his teeth white as he smiled.

‘When will the floating bridge be finished?’ he said, after a time. The question made nothing of what would be one of the marvels of the age, if their engineers pulled it off. The Hellespont had never been spanned, not in ten thousand years.

‘The first hulls will be in place today,’ Xerxes said, pride showing. ‘Persia is the light of the world, Mardonius. We have machines to draw wind from the air, water from the ground. This is merely the work of slaves – of ropes and wood and piles sunk into the mud beneath. Master Baloch tells me they will be stable enough to cross in a month, barring storms. If the crossings survive the winter, you will ride across that strait in spring, general, without the sea wetting the hem of your coat. I will set sail on the same day. With God’s favour, we will achieve our victory before the end of the year.’

‘The Greeks will surely know we are coming,’ Mardonius said. He bit his lip at the thought, but he was the leader of all the armed forces of Persia and he worried about overconfidence.

‘Of course they will,’ Xerxes replied. ‘They have had spies in Ionia since they burned Sardis, reporting back in whispers. Half the people on this coast claim ties of blood to the Hellenes. They talk and write and warn every day. It does not matter. No doubt, too, they will have noted our supplies in Thrace and marked the likely route we will take.’