Athough historians doubt the tale told by Diodorus of a Spartan raid into Xerxes camp on the night before the final battle at Thermopylae,
the story is just too good to exclude from a novel. Here's an excerpt from "A Heroic King," which describes how it may have come about.
"So what?" Prokles answered. "He came out of Xerxes camp, and he knows where the bastard's tent is."
"But why should he lead you to it?"
"Because I'll have a sword up his ass!"
"So he'll lead you to Hydarnes' tent, and when you're surrounded by Immortals, he'll squeal."
"So what? Then I die sooner rather than later. What the hell difference does it make? But if I can get him to lead me to the Great Asshole himself, there's a chance I could cut off the snake's head. If Xerxes is killed, that whole anthill won't be able to take another step!" Prokles was gesturing contemptuously toward the Persian positions. "They'll be headless -- or rather, all Xerxes' brothers will be so busy fighting one another for the throne, they won't have another thought for us. That's the real advantage of their polygamy, you know; they produce packs of royal whelps who hate one another more than anyone else in the world."
"And what do you propose to do? Stroll through the West Gate by the light of the full moon and say 'cheers' to Persians sentries as you walk past?"
"You're still a stupid little--"
"Prokles!" Leonidas cut him off and turned to Dienekes. "Everything alright?"
"Yes, an eager young lad by the name of Gylis is on his way right now. What's this all about?"
"We have in the form of this Tyrrhastiadas of Cyme," Prokles answered, "a man in our midst who knows the exact location of Xerxes' tent. He could lead me to it. All I need to do is slip inside --"
"The unguarded, isolated royal tent--" Alkander mocked sarcastically.
Leonidas clapped his hands once sharply to shut Alkander up, and Prokles continued, "And cut his throat. Then the whole war, let alone this battle, will be over."
Leonidas looked straight at Dienekes without a word.
"It sounds like a good idea to me. I'd say, six men. No more and no less."
"Why so many? THey'd just attract attention!" Prokles protested.
"The idea is too good to put all our hopes on the likes of you!" Dienekes retorted bluntly. "We should send in two teams of three men each. One can take the path that leads up from the Hot Gates over the spot where Xerxes had his throne. The helots can show the way up, and our deserter can show them the way down. The other three can take a fishing boat around to the back of the camp," he gestured vaguely toward the lights that dotted the dark stretch of the coast beyond the Malian Gulf. "From there they can ask their way to Xerxes' tent, which will hardly be a secret. Given the number of Ionian troops with the Great King's army, no one will take any note of a trio of Greek hoplites. We should have thought of this days ago."
"Choose the men, Dienekes -- anyone but yourself," Leonidas warned.
"For the three men to go over the mountain: Mindarus, Labotas, and Gallaxidoros. They're all born mountaineers, used to hunting in the harshest parts of Taygetos. For the sea route: Prokles here, Bulis, who speaks some Persian and has seen Xerxes face-to-face, and...." He paused for a moment, thinking carefully, before deciding, "Temenos."
Leonidas started slightly at this last choice, but he had told Dienekes to make the selection and had no grounds for calling his decision into question. "Fetch them," he ordered Meander.