The first test of a fleet engagement was in the courage of its captains, Themistocles knew. He and Xanthippus had trained the men as best they could, though the Spartans had scorned it, saying they knew full well how to approach an enemy and would take no lessons from Athenians. Xanthippus had talked the other captains through those first moments even so. Some of the Spartans had set aside their pride, at least when Eurybiades was not present.

War galleys approached prow to prow and ram to ram. It was an impossible blow. Even a perfect line would see both rams grinding away down the sides and the ships passing one another at boarding range. The danger then was all for the oarsmen. Themistocles gripped one fist in another behind his back. He thought of those massive wooden bars wrenched out of hands, crushing men.

There had been one accident in training, with two ships shearing against one another and cripples made of good Athenians. The example had not been lost on the rest, with a dozen dead and broken men taken off at the port, unable to walk again. The lesson – and the warning – was clear enough. A single glancing blow could ruin a galley’s ability to move, leaving them helpless for a strike below the waterline.

The answer was to have keleustes and oar crews ready to pull in the oars on one side, just as soon as they knew which way it would go. Boarding crews stood ready then, with shields and swords or spears on deck, waiting for the grinding note and screams from those too slow to move on either side.

Themistocles felt his throat had gone dry. He wondered if Xanthippus was experiencing the same sense of sand and dust in his mouth. The man had recalled it being the main thing he remembered from standing at Marathon, years before. Themistocles felt a tap on his leg and looked down at the signal boy, holding up a waterskin.

‘Thank you,’ he said, pulling off the cap and directing a flow of blood-warm liquid into his mouth. It helped and he smiled, making the boy beam.

Beat by beat, the fleets soared together, their speed seeming to increase as they came within a dozen ship-lengths. The waves were calm, but thousands of oars chopped hard at them, battering them to foam. Themistocles called for his boarders to be ready once again. He wore a pale blue cloak over a breastplate, with a helmet ready at his feet. Few of the boarding crews wore armour of any kind, to give them a chance to survive falling in.

Themistocles felt suddenly helpless, a passenger whose heart thumped fast and hard in his chest. He had a silver coin around his neck that his mother had given him. It had a stamped image of Athena’s owl in the silver, polished by decades against his skin and hers. He kissed it, pressing it long against his lips as Xanthippus and the Spartans crashed into the Persian fleet ahead.