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.