Napoleon frowned at his subordinate. ‘I’m not a fool, Junot. I know we’ve failed. But I can hardly say that to the men, particularly as we face a hard march back to Egypt. But if they believe that I believe we have achieved something it will put some heart back into them. Got it?’

‘Yes, sir.’

‘Then have that copied and distributed to the army at once. On your way out, send Dr Desgenettes in.’

Junot saluted and strode through the tent flaps. Napoleon shifted uneasily on his chair.The next interview was going to be a difficult affair but there was no putting the matter off. As soon as the heavy guns had exhausted their ammunition they were to be spiked before the rearguard pulled back, following the rest of the army. Once the French army began to retreat the enemy would close up on them and harass the column all the way back to the fortified depot at Katia.The army would have to march as fast as it could, and that meant some sacrifices would have to be made, Napoleon reflected. He glanced up as a figure entered the tent.

‘You sent for me, sir.’ Dr Desgenettes stood hat in hand before Napoleon’s desk. He looked pale and exhausted and there was several days’ growth of stubble on his face.

‘Yes. Sit down, doctor.’ Napoleon clasped his hands together as he continued. ‘You know that the army is about to break camp?’

Desgenettes nodded. ‘Junot told me about the retreat, yes.’

Napoleon smiled faintly. ‘The correct term is withdrawal, doctor . . .We will be abandoning the heavy guns, and any other burdens that might slow us down, and that’s why I need to speak to you.’

Desgenettes looked confused for a moment before he realised what his commander was implying, and then his expression instantly changed to anger.‘The men in the hospital.You want to leave them behind? Have you any idea what the enemy will do to them, sir?’

‘They could be treated fairly.’

‘After what happened to the prisoners at Jaffa? If we left them to the Turks we’d be committing murder, sir.’

‘Then, if we cannot take them with us, let’s not leave them to the Turks.’

Desgenette’s eyes narrowed. ‘What are you suggesting, sir?’

Napoleon paused, frustrated that the man was forcing him to spell it out. ‘I’m suggesting that for those men who are too sick to move, or who would slow us down, an overdose of opium might be the most humane solution.’

‘You would kill our men?’

‘Not me. You. I want this task carried out by someone who knows what to do.’

‘Sir, I am a doctor - a healer, not a killer.’

‘Is it not the case that a doctor’s duty is to alleviate pain and suffering?’

‘Do not dissemble with me, sir.’ Desgenettes shook his head. ‘I refuse to do it.’

‘It is not a request. It is an order. If you disobey me you will be committing mutiny.’

Desgenettes slapped his chest. ‘Then shoot me! I will not kill our countrymen.’ He paused a moment and looked at Napoleon shrewdly.‘But then I’m forgetting.They’re not your countrymen, sir.’

Napoleon took a sharp intake of breath. ‘How dare you speak to me like that! Doctor, you forget yourself. I am your general and while you wear a uniform you are a soldier first and a doctor second.’

‘My medical oath takes precedence, sir. In any and all circumstances.And you will have to shoot me and my staff before you reach my patients. Then you’ll have to murder them yourselves. I hardly think the rest of the army will approve of such actions, however much they revere General Bonaparte.’

Napoleon glared at him for a long time, wanting more than anything to have this man immediately taken outside and shot for his insubordination, but he knew that the army would not stand for that. Desgenettes, like most doctors, enjoyed the respect, gratitude and open affection of the common soldiers. It would be dangerous to harm the man, Napoleon realised. He forced himself to smile.

‘Very well, doctor, there are now over two thousand men on the sick list. How do you propose to move them?’

‘A good number of them are walking wounded. The rest can be carried on horses, camels and stretchers. At least as far as Jaffa, where we can put them on ships.’

Napoleon considered the proposal. The siege would be lifted in three days. Time enough to move the sick and wounded to Jaffa. He looked at Desgenettes and nodded. ‘Very well, doctor, you have convinced me. Make the arrangements immediately. You can draw on men from Lannes’s division to act as stretcher-bearers. Now, leave me.’

The rearguard had spiked the siege guns during the night, and as dawn broke on 20 May huge columns of smoke billowed into the sky as General Reynier’s men set fire to the supplies and equipment that were being abandoned by the French army. As soon as the rearguard pulled back, the Turks in Acre swarmed out of the gates to pursue them, forcing Reynier to skirmish all the way to Jaffa. Napoleon had arrived in the port a day earlier and was shocked to discover that only a handful of small ships remained. The houses and merchants’ storerooms along the quay were packed with sick and wounded men.

‘Where is Admiral Perée?’ he demanded.

‘The admiral sailed for Alexandria yesterday, sir,’ Berthier replied.

‘Why? I gave him orders to take Desgenette’s patients on board.’

‘The admiral said he could not risk having any plague victims on his ships. He also said that he must leave before the Royal Navy blockaded the port.’

‘Damn the admiral to hell,’ Napoleon muttered in fury as he gazed at the men slumped in the shade along the quay. The transfer of the sick and injured from Acre had exhausted the patients, and those assigned to help them. Only a small number of them could be found berths in the vessels that remained in the harbour.

‘Tell Desgenettes to have the worst cases loaded on to these ships as soon as possible. Those who are too sick to move, and those who are least likely to recover, are to remain in Jaffa. Tell him that they must be dealt with humanely after all.’

Berthier looked at him curiously but Napoleon just shook his head. ‘Don’t worry, he’ll understand the order well enough.’

As the last ships put to sea Napoleon and the rest of the army began the march south along the coast.The wounded who were forced to walk did their best to keep up, and for the first few days their comrades did all that they could to help them along. Then, as exhaustion, hunger and thirst began to take their toll on the men, the weakest were left to fend for themselves, and the tormented cries of stragglers taken and tortured by the enemy haunted the men gathered round the campfires each night. The army trudged into Gaza on the last day of May and filled their canteens and haversacks with the remainder of the rations as they steeled themselves for the crossing of the Sinai desert.

By day the Sinai was smothered by blistering heat that sapped the very last dregs of energy from the men as they limped forward with cracked lips and parched throats. Those of the injured who died were unceremoniously pitched into the sand and left to feed the carrion that swirled in lazy circles as they followed the army across the wasteland. Discipline became as fragile as the bodies that depended on it, and the hostility of the men was evident in their glares and the bitter tone of their muttering whenever Napoleon and his staff rode by. So Napoleon gave up his horse to help carry the wounded, and ordered his staff to do the same, and they walked the rest of the way, alongside the straggling columns of their men.

At last, four days later, the first soldiers arrived at Katia, under the horrified gaze of those watching from the walls of the fortified village. The men of the army that had invaded Syria were barely comprehensible as they croaked their requests for food and water, and when these were brought to them they tore at the food and drank like wild animals.