‘When armies march, authority is whatever they can take and keep,’ Themistocles said grimly. ‘Or would you stand in front of an army holding a property deed, crying out that they have no permission?’

He made a growling sound of frustration, deep in his throat. There had not been a month in three years without some report of Persian ships, of Persian gold, of Persian soldiers like grains of sand.

‘How many times have we listened to these reports now?’ Themistocles said. ‘Always, there is something to gossip over in the markets.’

‘This … is not gossip, Themistocles,’ Nicodemus said. ‘The Great King himself has joined them. We have it from men who saw him on the coast. He is his father’s son and he is looking across the seas to the west.’

Themistocles scowled. Fear seemed to grow with age. It was the strangest thing, like rot that ran through the heart of good wood. Young men felt too little fear, but then somehow it crept in and spread. He looked at Nicodemus and saw the old archon was afraid. With an effort, Themistocles gentled his tone.

‘Tell me, are they just securing their western border or truly planning an invasion?’

‘It is impossible to know for sure,’ Nicodemus admitted. ‘I suspect the Great King himself does not know. Yet the numbers, Themistocles! One of our people watched them mark out a field and count the number who could stand within the ropes. For a day, they filled that field over and over. Our friend was moved on and lashed for his curiosity, but he said he had never seen so many. He said … at least two hundred thousand, perhaps twice as many again.’

‘That is impossible,’ Themistocles said scornfully. ‘If he said that, he was trying to make you fearful. Even counting slaves and women, you are describing all of Athens, just about. Who could even feed so many on the march? They would starve.’

‘Some will come by ship, with holds full of salted meat and casks of water. They have the entire Persian empire to feed them.’

‘How many ships?’ Themistocles demanded.

‘Hundreds. We do not know the number.’

‘What good are you, then?’ Themistocles snapped.

He closed his eyes for a moment as they recoiled, furious with himself. There was no honour in barking at old men.

‘I apologise,’ he said, bowing his head. ‘You will understand the news is disturbing. We thought they would come after Marathon, but they did not. All word ceased out of Persia and there were some who argued that we would never hear from them again, that we had earned peace with a single battle. Do you remember those days, Nicodemus?’

‘Their king died,’ the old man said.

‘Yes. And his son, this Xerxes, still remembers us. If we could only know his mind!’

Themistocles began to pace. The heads of the old men followed him back and forth, as if in a trance.

‘We have had years of rumours and reports,’ Themistocles said. ‘Talk of armies drifting in and training and taking over the cities of Ionia. We live with the threat of invasion – though our great fleet patrols day and night. We will give thanks for the wisdom of that if they come!’