‘Come down from there, Xerxes,’ the Great King said softly.

His son nodded and put out one hand so that his elephant could see. The trunk curled round and he stepped onto the muscled length, brought to the ground in perfect smoothness. The boy seemed proud of it. Darius showed no reaction to a trick more suited to the markets or the logging camps. He put his arm around his son’s shoulders and walked with him to where he should have been standing, waiting on his father. There, Darius rested one hand on the great stone, feeling its warmth.

‘You see that city?’ he said. ‘Dark with ash?’

Xerxes made a show of peering in the distance before he nodded, still unbending. Darius found he was proud of the young man who would surely follow him, if Ahura Mazda, the Lord of Wisdom, allowed it. It did not pay to be too sure of the future, aloud or in the most private thoughts. The God of Light heard all.

‘It is Sardis, the capital of this entire region,’ he said. ‘Or it was. It was sacked by an enemy and burned, including the great temple that had stood for two thousand years. This is why I brought so many soldiers, Xerxes. By tomorrow, every home and temple will be cleared to the foundations. We will rebuild it all.’

‘Who would dare attack one of our cities?’ Xerxes asked.

‘Men of Athens, men of Eretria,’ his father replied. ‘The Greeks. I thought … They sent ambassadors here a dozen years ago, asking for friendship. I thought they had agreed to become one of my chosen – my beloved subject peoples. They gave earth and water to my governor and they went home, across the sea. I confess I hardly thought of them after that.’

The king smiled and tried to ruffle his son’s hair. He hid his hurt when Xerxes pulled away.

‘This is the edge of the world, Xerxes. The sea lies not two days from here – and beyond it, lands which have never known the blessing of our laws, our soldiers.’ He waved an arm over the plain. ‘I rule here, from the slave markets to the gold mines. Every pot and cup is mine, every coin and beam and child. Yet we are a long way from civilisation, from the heartlands. Perhaps I have been too gentle with them, too forgiving. I trust too easily. It has always been my weakness.’

He saw his son shift uncomfortably and smiled.

‘No man can say I am without honour, Xerxes. Can you accept that? If I give my word, I keep it, though the world falls around me. If I forgive an enemy, if I welcome him as a child into my house, he knows there will be no more anger from me. Even the Greeks know this. Oh, they may shout and struggle, but for those who are men, who are willing to put aside their pride and offer me tokens of earth and water, I will be always a forgiving god.’