They worked their way steadily along the bank, choosing the points where the ground was most solid and the bank posed no obstacle to the swift crossing of the river. When the last site had been marked on the map they turned to make their way back across the island to the Emperor’s forward headquarters. Behind the screen of forests that surrounded the heart of the island sprawled a vast camp. Marshal Oudinot’s corps had joined Masséna’s men, and once night came Davout’s thirty-five thousand soldiers would swell the ranks of the army waiting to be unleashed on the unsuspecting Archduke Charles. Obedient to their strict orders the men had not lit camp fires, and sat quietly resting. Some were stretched out asleep, others were cleaning their weapons, the cavalry rasping whetstones along the edges of their sabres. Although no orders had been issued for any attack, the concentration of so many men was evidence enough that their Emperor was preparing for an imminent battle.

As they walked through the camp Napoleon felt the keen sense of anticipation amongst his soldiers. So different from little over a month earlier when the army had been thrust back on to the island by the Austrians. Napoleon’s brow creased into a frown as he recalled the scene. The survivors of the battle had slumped on the ground in exhaustion. Thousands of injured men had been forced to spend two nights in the open, and hundreds had died from their wounds and been buried in a mass grave on the south of the island.

Eventually the wounded had been evacuated to Vienna, including Marshal Lannes, whose legs had been smashed by a cannon ball. With both legs shattered the imperial surgeon, Dr Larrey, had no choice but amputation. Napoleon had gone to his friend’s side after the operation and found the veteran of many campaigns lying on a bed in a small chapel. A thin sheet covered Lannes and his arms lay at his sides. The sheet fell flat to the bed from his thighs down. Lannes was in a troubled sleep, his face slick with perspiration, as Napoleon and Dr Larrey entered the room.

Napoleon turned to Dr Larrey and asked quietly, ‘What are his chances of surviving?’

‘Good enough. The marshal has a strong constitution. Provided there is no corruption of the wound, the stumps will heal in time.’

Napoleon nodded. ‘Keep me informed of his progress.’

‘Yes, sir.’

Napoleon glanced back through the door and felt a great sadness over the knowledge that the courageous and utterly dependable Lannes would never again be at his side during a battle. It would be hard for a man so full of vitality to accept life as a cripple, Napoleon realised. As he closed the door, he wondered if it might not have been kinder if Lannes had been killed outright.