On the first day, they had merely watched, as if they observed a truce or accepted rules in war. On the second evening, they had suddenly rushed in, killing a dozen men in the water before the hoplites shield-rushed them, driving them back. Persian soldiers had patrolled the banks all night to deny them another chance then, tramping back and forth. There was malice there, as well as understanding. Soldiers needed water in a dry land. The Persians tormented the Greeks with what they had to have.

No one knew what the Persian master of horse would order that morning, but the situation was becoming desperate. The Greeks had endured the slow movement of the sun over exposed ground all the previous day. They had sweated in that heat. Each waterskin had been tallied, each swallow counted. To a man they had grown darker, dry and sore, their lips cracking. They would be desperate in a day or two – and then mistakes would be made.

Aristides looked back to his hoplites, waiting in patient ranks of bronze. They knew the stakes.

‘Brothers – gentlemen of Athens!’ he called to them. ‘It is time. When I give the word, you will advance in good order, locking shields. Our water-bearers will go in behind the safety of our lines, filling skins as fast as they can. You will then wait for my signal – there will be no retreat before you hear my order.’

He looked over to the Persian horsemen, their movements subtly increasing in speed and sharpness. The wasps knew their moment was coming; they could sense it. There had to be a thousand of them, more than before. Aristides could see their leader on a monstrous black stallion, turning the beast on a tight rein. They had grown confident, enjoying the snare the Greeks had made for themselves.

‘You will have to endure spear and arrow,’ Aristides said. He shrugged. ‘Keep low and remember your shield drills. If they come too close, you may be tempted to advance and cut those colourful whores down. You will not! They test us, test our resolve, that is all. You’ll get your chance when we advance with the main force, not some pointless little action here. Your task today is simply to secure water for tomorrow. That is all.’

He glanced at the archers, still crouching in the cleft of land.

‘You lads. Stay behind my men, out of sight. You have all marked the one we want. Wait on my order, if he comes close.’

They nodded. Five were from Corinth, with a Megaran and four Aeginetans, a dour little group who muttered Greek in a thick dialect of their own. They seemed to understand him, however, looking out with burning eyes on the enemies of their people.