Note: the Persian capital was Paarsa. I have used the Greek name for it, Paarsa-polis (city of Paarsa) or ‘Persepolis’, throughout as it’s better known.

Over four or five years, news spread of the huge invasion force being gathered in what is now modern-day Turkey. When Aristides and Xanthippus were summoned home early from exile, it can only have been with the connivance of Themistocles. Their personal feuds were simply put aside for the greater good, which is extraordinary. Xanthippus took on a senior role in the fleet. Aristides was given command of the main force of Athenian hoplites and took them out to join the allied city-states.

First contact with the Persian fleet was off the island of Sciathos. The Persian sailors seem to have made heavy weather of the unknown coasts, taking it very slowly. However, ten of their scout ships came across three Greek triremes left there to carry warning.

The Persians rammed and sank one Greek ship. They sacrificed a particularly handsome sailor on the deck of his own ship for good luck. The second Greek crew was overcome after a fierce resistance. The final trireme made it to the mainland and the crew took off over land. Meanwhile, three of the Persian ships ran aground on a bank out to sea, which they then marked with a stone pillar brought for that exact purpose – to show the danger to those following. This was the first incident of the Persian war of 480 BC, and it was a complete disaster for the Greeks: surprised, overwhelmed by superior numbers and massacred.

The fleet of Xerxes lost many more ships to storms as they came south, though exact numbers are unknown. In strange lands, they hugged the shore and tried to keep the army under Mardonius in sight at all times. The plan was to reach Athens by land, after crossing a final range of mountains – through the pass known as Thermopylae. At the same time, the Persian invasion engaged the combined Greek fleet at sea for three days of fighting along the strait near the town of Artemisium. (It seems to be just a coincidence that the queen of Halicarnassus was called Artemisia.) The number of Persian ships was reported at around 1,200, though it may have been as low as six or eight hundred.

The battle of Thermopylae took place at the same time, on a strip of coast that was the only way past the range of mountains. The sea has retreated there today, with new land creeping in. It is no longer possible to see what Leonidas saw, not exactly. Yet he would have been in contact with the fleet. For three days or so, he prevented the Persian advance on land, while Athens and her allies fought their fleet at sea. It was a coordinated effort – and the purpose was to give the main Greek forces time to assemble and make ready.

It is true that Leonidas had been to the oracle at Delphi. There he was told that the Spartans would mourn the loss of their city or the loss of a king descended from Heracles – the bloodline of Leonidas. In essence, the king would have to choose between saving his own life and saving Sparta. I suspect that explains why he did not leave the pass of Thermopylae, even right at the end, when he sent most of them away and remained with just his elite guard, and around a thousand others. Interestingly, his helot slaves remained with him, though they would have known there was no escape at that point. Leonidas knew it was the end – and he accepted it. For some reason, that aspect of his thinking does not usually feature when the story is told, though it may be the most heroic part.