I sought out the bosun and explained that Captain Oliver had agreed that the evening water ration should be used for the broth. He himself carried the buckets down to the cook’s galley, as if he did not trust even me not to make off with it. While I had been gone, the cook had lit the fire in his stove and he now lifted down a great iron pot, into which the bosun poured the precious water.

I found one of the cook’s sharp knives and set about chopping the strips of dried meat very finely, while he chopped the onion and carrots. The bosun lingered, watching us hungrily. I did not feel very sympathetic towards him. He too had rested and eaten in Cascais while we had dragged ourselves overland. As we worked, I noticed that there were some bunches of dried herbs hanging from the beam above his head.

‘Can we add some of those, for flavour?’ I asked. The meat and vegetables, now added to the pot, were barely to be seen.

‘Aye,’ the cook said, reaching up. ‘There’s thyme here, and marjoram.’

He chopped them swiftly with that skilled rocking motion professional cooks seem to use so casually, then stirred them into the pot. It still looked more water than broth. He placed a lid on the pot and drew it to the edge of the iron grid above the fire.

‘Don’t want to boil away the water,’ he explained. ‘I’ll just keep ’un simmering very low.’

The men were grateful for our attempt to provide at least something like food that evening, patiently holding out their cups for their share. Even the sailors were too weak by now to argue or push others out of the way. Despite the thin broth, barely tasting of the meat, the onion, the carrots, and the herbs, more men died in the night, and more bodies went overboard next day. The other ships in our depleted fleet were keeping pace with us, and we could see the dead from those ships following ours to the depths of the ocean.

I began to wonder if all the ships, empty of sailors and soldiers and gentlemen adventurers, would eventually sail on by themselves over the oceans unmanned, until they fetched up on some foreign shore – the West Indies to the south, or Virginia and the Chesapeake, where my tutor Thomas Harriot had once voyaged to meet the native peoples, or perhaps far to the north, to Iceland, which I had heard was a strange country of volcanoes and earthquakes, of spouting geysers whose boiling water rose out of the snow fields, and of islands that sprang new-made from the sea. Perhaps the Victory would crash eventually into one of the great ice floes, inhabited, as I had read, by huge bears as white as the snows amongst which they lived.

By now I was growing light-headed from lack of water and food. Hunger does strange things to the body. At first no more than a whisper in the stomach it grows and grows until your whole body is filled with a gnawing pain, as a glass is filled with water. The analogy of the water glass came to me as part of a weird hallucination which accompanied the hunger, a feeling that somewhere there was both food and water, if only I could find them. I had to stop myself roaming the ship, searching. Soon that pain walked everywhere with me, so that it was difficult to think of anything else, but I must think of my patients. I had to struggle to sustain my role of physician.

My salves had been running low at Lisbon and I had had no chance to replenish them during our brief stay in Cascais. I did what I could now, for the wounded, but the men were so weak and exhausted, their bodies drying up and crying out for sustenance, that Nature’s own healing power was unable to help them.

I thought with regret of the long cool wards of St Bartholomew’s, with their rows of tidy beds. The sisters – as we called them, after the nuns who had served there in the past – kept the bedlinen and the patients clean and sweet. In the case of many of the patients, probably cleaner and sweeter than they had ever been in their lives before. The food was plentiful and wholesome, our salves and potions, based on my father’s long and patient study of Arab medicine, were the best known to man. We had our own apothecaries, our abundant supplies of all the medicines we needed. Even in an emergency, as when the survivors of Sluys had been brought it, we were able to help most of the patients. Every week the governors of the hospital paid a visit of inspection, to check that the patients were properly cared for, were clean and fed, and that physicians, surgeons and sisters, were all mindful of their duty. That whole world of hospital medicine seemed now like a phantasmagoria, so remote was it from the squalor in which the pitiful remnant of our army lay dying and I crouched beside them, powerless.

The next morning, I knelt by the side of a soldier with a bullet wound in his upper arm that would not heal, although I had extracted the bullet days before. He was one of those who had been discovered lying injured outside the camp after the Spanish night raid.

‘Do you feel pain here, or here?’ I asked, probing the lower part of his arm.

He gazed at me with dull eyes and shook his head. ‘I cannot feel your finger, Doctor. Not separate, like. The whole arm is too b’yer lady painful!’ He tried to give me a smile, and I could have wept.

There was no fresh water to wash the wound, but I had dipped up a bucket of salt water, and that is sometimes more efficacious. I am not sure whether it is the salt, or perhaps some essence from the seaweeds that makes it so. He endured the cleansing bravely, and when I had smeared on a little of my last, precious salve, he lay back on the deck with a sigh. I could smell the unmistakable sweet scent of gangrene setting in, like fruit beginning to rot, which mingled with the sour, sweaty stink of him. The arm ought to be amputated before the gangrene reached his heart and lungs. It is no part of a physician’s business to perform amputations, although I supposed I might do it if there was no other way. I knew there was a naval surgeon on one of the other ships. We could signal to him to come over to us, but I decided against it. The man was too weak to survive amputation. He would have died of shock before the operation was over. It was now simply a matter of how long it would take him to die.

I could, however, give him something to ease the pain a little. In my cabin I checked my few remaining supplies. Over the flame of a candle I made an infusion of spiraea ulmaria, matricaria recutita, and humulus lupulus in my own morning cup of water, which I had not yet drunk, lacing it with nearly the last of my poppy syrup, then I returned to the deck and sat down beside the soldier.

He roused himself again and tried to sit up, so I slid my arm under his shoulders and helped him drink the medicine.

‘This will ease the pain,’ I said, and he nodded.

Then he lay there with his head on my shoulder, looking towards the ship’s bow.

‘Don’t suppose I’ll never see England again, Doctor.’

‘You must keep your spirits up,’ I said. ‘A stout heart is better medicine than any I can give you.’ I knew that I lied, and so did he.

‘Ah, but you’re a brave lad, Doctor, young as you are. Once I was in my right mind again, I never thanked you for the way you sucked that snake’s poison out of my leg. That was a brave thing you done, braver than any soldier.’

I looked down at him. In all the weariness and dirt I had not recognised him.

He nestled closer against me, and murmured, so quietly I could barely hear him, ‘You hold me soft as my Molly. And I won’t never see her neither. She warned me.’ His voice had almost faded away. ‘She warned me . . . not to come.’

He died within the hour, and all the while I held him. I never knew his name, or where he came from, whether Molly was his wife, whether there were more orphans made by this death. When we dropped him overboard I wept, and I shut myself in my cabin for the rest of the night. I do not know why I wept, for this one man out of so many. Perhaps it was because I had saved him once before from death, but could not save him this time. Perhaps it was because he had died in my arms, like a lover. Perhaps it was because, in his wasted, filthy, wounded body, he stood for all those other poor creatures who had died shamefully, caught between their own greed and the insubstantial dreams of old men, who were exiles from a country that no longer existed, had never existed as they imagined it.