For several days Napoleon rarely emerged from his quarters in the palace. It was hard to bear the shame of being almost the last man to know the truth about Josephine’s treachery. He sensed that those around him regarded him with a mixture of pity and amusement, even though they struggled to hide their feelings. Soon the rest of the army would hear the rumours, if they hadn’t already, and their laughter would echo that of Paris society. The great general who commanded France’s armies and conquered her enemies, yet could not control his wife. Nor satisfy her as a man should. That Josephine should prefer a foolish, vacant-headed cavalry officer to him fell on his heart like a great weight. The recent victory, and all the others before, seemed no more than insignificant details now, and his immediate ambitions seemed futile and pointless. In an attempt to work through the dark thoughts whirling through his mind, Napoleon forced himself to write a letter to Joseph.

The words came slowly and painfully as he set down his feelings. ‘Glory is stale when I am only twenty-nine. I have achieved everything a man can in this life. And now there is nothing left for me but to become really and completely selfish . . .’

He looked at the last word on the page with loathing and despair. He must not let himself sink into a well of self-pity.There would be time for that later, when he returned to Paris and confronted Josephine. Meanwhile an army stood by, waiting for his orders. The fate of twenty-five thousand Frenchmen, and the future of an empire, lay in his hands.

Very well then, he decided. He would harden his heart and pursue his goals with utter ruthlessness. Every enemy he killed, every army he crushed, would be dedicated to Josephine and those who mocked him.

Napoleon led the army out of Cairo early in August. Ignoring Murad Bey and his Mamelukes for the moment, he tracked down the large host of ragged and poorly armed foot soldiers under Ibrahim Bey. Napoleon’s men had been issued with new, lighter uniforms and were accompanied by hundreds of commandeered carts and camels carrying casks of water. He marched them hard, driving Ibrahim Bey before him, until he caught up with the enemy at Salalieh. There was no battle to speak of, merely a bloody massacre as wave after wave of the fellahin conscripts were cut down by musket fire and grapeshot, until their bodies covered the ground before the ranks of the French soldiers. When, at last, the shattered remnants of Ibrahim Bey’s army broke and ran, there were few cries of triumph from the French ranks. Most men simply stared out across the piles of peasant bodies and blood-spattered sand in numbed horror.

‘This is not war,’ Berthier said quietly. ‘It is murder.’