The allies reached the high passes while the sun was still low, having set off in the dark that morning. The Spartans led the column, with Pausanias and Tisamenus at the spear-point. Their own runners were out by then, with horns around their necks to call warning if they found hidden men or a trap. Pausanias followed campaign rules for hostile territory. His helots had brought up the heavy gear. Each of the Spartiates now carried his own shield and spear, with a sword on his hip and the wicked kopis scabbard through a belt. For those behind, their cloaks were a swirling mass of red.

Pausanias saw the whiteness of the pass ahead, where the land dropped away and left only a glimpse of bare sky. He did not know what lay beyond and he felt his heart thump. It was not just his first sole command, but the first without Leonidas to make every major decision. He breathed long and slowly, forcing himself to calm. If he marched the army of Sparta to destruction, he would live for ever in infamy, as the man who had lost a nation. The responsibility lay heavily on him and he half-stumbled as he marched. Tisamenus glanced at him, understanding.

‘I have walked a long way, Pausanias,’ Tisamenus said. ‘Perhaps we should run for a time.’

Pausanias glanced at him. He was trembling, as much in excitement as in nerves. There were ears listening all around, perhaps men who would report idle talk at home. He kept his mouth still. He was the regent of Leonidas’ son, Pleistarchus! Before the end of the year, that boy would be declared battle king – and Pausanias … would be free. Or dead, but no longer regent, no longer first soldier in Sparta.

He swallowed, shifting his grip on his shield. How odd that his throat seemed stiff and swollen! There had been furious discussions between ephors, he knew. No one had failed to understand the stakes of that campaign. If the council of ephors had ordered Pleistarchus to lead, that would have been the end of it. Yet Spartan laws were iron. Until Pleistarchus reached his eighteenth birthday, he could not command men in war. Until he sired a son, he could not leave Laconia. His bloodline was just too precious.

Pausanias murmured a prayer to Apollo, giving thanks for the boy’s discipline. There had been pain there, of course, when the ephors told Pleistarchus their decision. It would certainly have hurt the son of Leonidas, already wounded by the death of his father. Yet he had obeyed – the secret rule of ‘peitharchia’: total obedience, even unto death.

Tisamenus looked across to him, waiting for the word. Pausanias felt a wild urge to break into a sprint and throttled it down, with Leonidas and his son as inspiration. They would be disciplined, but not slow.

‘Double speed,’ Pausanias called to the others.