The second sacking was every bit as traumatic as you might imagine. Violence erupted among the refugees as they argued whether to accept the Persian offer. Some were stoned to death, killed by their own. The Athenian strategoi sent messages to Sparta, saying they could not endure another attack. Unless Sparta sallied out in the spring, they would become allies of Persia. Crucially, they threatened to surrender their fleet to Persia – a fleet which could then land anywhere on the Peloponnese peninsula where Sparta lay. If that had happened, there would have been no great flowering of Athenian politics, democracy, art and philosophy beyond that point. None of the great playwrights would have flourished under a dictatorial Persian rule. Between them, over a decade, the Athenian hoplites at Marathon, the crews at Salamis and the Spartans at Plataea all saved Greece.

The main Persian commanders at Plataea were Mardonius; his second, Artabazus; and Masistius, master of horse. There is a question mark over whether Hydarnes, commander of the Immortals, was there. Herodotus mentions him refusing to leave the side of Xerxes, so he might have gone home when the king left. However, the record is a little confusing, as Xerxes seems to have given Hydarnes a role in bringing the army home – and the army remained in Greece.

The battle of Mycale is traditionally said to have occurred on the same day as Plataea. They were hundreds of miles apart, however, so it’s impossible to say. Xanthippus was there, with King Leotychides of Sparta in nominal command of the fleet. There is no record of Pericles and his brother Ariphron being present. Without a solid record of where they were, I put them where they might have been. It is somehow surprising that there is no record either of what happened to Ariphron, or even the name of Pericles’ sister. They vanish from the record. However, I needed to explain the horror that followed – where Xanthippus is impossibly cruel. Punishment by crucifixion was not uncommon, but is still utterly out of character for the man – the only time in his life something of that sort is recorded. For that reason, it made sense to give him a reason to hate.

The image of the swallow flying from darkness, through a lighted room and out into the dark once more, is from The Rubáiyát of Omar Khayyám – an anachronism here, as he lived some fifteen hundred years after Xanthippus. However, the image appeals to me, though I have hopes for whatever lies beyond the room.