As we drew nearer the coast, the wind began to rise, blowing strongly from the southwest. Clouds were building up and the sky grew dark. It would be a rough crossing to Dover and as we met the first waves offshore, several of the soldiers turned pale and one began to puke. A sailor took him roughly by the shoulders with a curse and thrust his head over the starboard gunwale of the ship, so that the wind carried the vomit away into the sea. The ship began to dance and pitch, but the sails were soon raised and she heeled over and began to cut through the waves like a dagger through silk. I drew a deep breath of the salt-laden air. It was wonderful to be moving swiftly at last, and the Good Venture stood out into the open sea with her starboard side low in the water. I saw that Andrew, solidly confident on shore, wore a look of some alarm.

‘We shall need to give the shoals off Flanders a wide berth,’ Captain Faulconer said in my ear. He had come to stand in the stern beside the helmsman, keeping a sharp eye on the course he was steering. ‘The Hollanders may know those waters without marks, but I am not so confident. They shift constantly. They may not be quite as much of a death-trap as our Goodwin Sands, but I should not like to find myself amongst them with the dark coming up as fast as it is.’

It was indeed growing dark. We must have taken longer to navigate the canal than I had realised. We were more than a month past the summer solstice now, and it must be nearly ten of the clock. In our haste to make the crossing before the Spanish fleet moved nearer, we had not taken a meal sitting in the captain’s cabin, but had eaten, like the sailors, on the wing, helping ourselves to rough chunks of bread and some sort of meat pasty, brought out on deck in buckets. For a moment, a chill finger of fear touched me, so that I shivered. I should not like to navigate these waters in the dark, between an armed enemy fleet and the dead hand of the Goodwins.

We had been sailing, I suppose, a couple of hours south along Flanders, but standing off from the coast, when I noticed a flickering light ahead of us. Although we seemed to be moving fast, the wind was almost head-on, so that the sails were close hauled. And although we had caught the last of the ebb tide as we left the Low Countries, the tide had turned now and was against us. So that, though we appeared to be moving rapidly through the sea, we were probably not making nearly as much headway relative to the land.

The captain, who had gone forward for a time to see to the close adjusting of the sails, was coming back to the stern, where I had found myself a seat on a water barrel. I had not seen Andrew for some time and wondered whether he too was feeling the effects of sea sickness.

‘Captain,’ I said, pointing ahead and slightly to port, ‘what is that bright glow over there? It looks like the lights of a great city, but I thought there were only small towns along this coast.’

He came to stand beside me and raised his hand above his eyes to cut out the small amount of moonlight breaking through the racing clouds. For a long moment he said nothing.

‘Fire. It is fire.’

‘Fire? Would the Spanish have set fire to a town? I thought they were well within their own territory.’

‘No. I think not. It looks like fireships to me.’

Fireships! I knew what that meant. Floating infernos that could wreak terrible destruction. Loaded with gunpowder, they would be set alight, their sails trimmed to carry them down on an enemy fleet, while their emergency crews leapt into boats and escaped. Only a few years before, the Dutch had used fireships in an attempt to break the siege of Antwerp by the Spanish, but they had failed and the city, one of the great cities of Europe, had been lost. Leicester had made an ill-judged attempt to send fireships down on to the Spanish besiegers off Sluys – his one effort to aid the garrison – only to have them turned back against him. Were the Spanish now using fireships against our English fleet?

‘Ours or theirs?’ I asked.

‘No way to tell, from this distance. We must go nearer.’

‘Nearer to the Spanish fleet?’ My voice shook with alarm.

‘We must.’ He was brusque. ‘If the Spaniards are sending fireships into our fleet, there will be men in the water. We cannot sail past and leave them to drown.’

‘They may be English fireships, sent against the Spaniards.’

‘They may.’

He turned away, shouting for his second in command.

‘This ship was commandeered by Sir Francis Walsingham,’ I said, ashamed of my fear even as I spoke. ‘Your orders were to sail directly to Dover.’

He barely glanced at me.

‘You are the only civilian on board this ship, Dr Alvarez. I have a crew trained in gunnery. Captain Joplyn has a squadron of men who can handle muskets or engage in hand-to-hand fighting, if it should come to that. Our duty now is to investigate and, if necessary, join our fleet to rescue survivors or engage the enemy.’

‘Well,’ I said with resignation, ‘at least I can patch up the wounded.’ I tried to appear calm, but the thought of sailing straight into battle made my stomach clench with fear.

‘Aye. That you can do.’ Faulconer turned away.

The fireships, if that was what they were, must have been farther away than I realised. With the wind and the tide largely against us as we headed even more south-westwards, dawn had broken by the time we came within sight of Gravelines, where the Spanish fleet had been anchored. Even before we could see anything clearly, we could hear the boom of cannon. The pall of black smoke cast by the fireships had been augmented by clouds of paler smoke from the ships’ guns. We could see the flashes as the cannon fired, followed by the ear-splitting crack of the explosions, like lightning in a storm, followed moments later by the crack of thunder.

As we had run south, the sailors not occupied in handling the ship prepared our own six cannon, and I found myself playing the part of one of those young boys, such as Captain Thoms had been, carrying gunpowder and shot up from the hold to place in readiness for the gunners on the gundeck. Andrew’s men had primed their muskets and stood watching expectantly as we drew nearer the battle. Even those who had been prone with sea sickness were on their feet, alert, looking eagerly ahead.

As I passed Andrew amidships, I said accusingly, ‘You and your men look as though you are enjoying this.’

He laughed. There was a gleam of wild delight in his eye. ‘This is what we are trained for, Kit.’

‘Well, I am not,’ I said dourly. ‘I am trained to save lives, not to take them.’

When we were at last close enough to make out something of what had happened, we could see the burnt-out hulks of eight ships and even to my untrained eyes it was clear that the fireships had been launched downwind from the English fleet on to the anchored Spanish ships as they lay, apparently securely, at anchor in the night. Now the Armada fleet was scattered across a wide expanse of ocean in disarray.

‘Our fireships have caused them to panic,’ one of the ship’s officers said in satisfaction. ‘By the looks of things they have cut loose from their anchors and fled in all directions. Medina Sidonia will have a fine time of it, trying to call them to order now.’

I thought with a shudder how terrifying it must have been to be roused from sleep to see a monster of fire bearing down on you, with nowhere to escape except by a leap into the midnight sea. And I knew that most sailors, superstitiously, refused to learn to swim, for they believed that, if you fell or were cast overboard, it was better to drown quickly than to struggle against death, only to drown in the end.

I saw the captain coming toward me and caught him by the sleeve.

‘The fireships were certainly ours, then?’

‘Aye.’ He grinned mercilessly, rubbing his hands together in glee. I had not seen him so animated before. But I thought of those men, leaping into the Channel, their clothes perhaps on fire, weighed down by their breastplates and helmets.