They failed again, and the next day too. By day four Tradescant ate a hearty breakfast and was at the rail to watch the fire boats try once more and felt as nonchalant as his men. Boredom and disappointment had driven out fear and now he wanted the battle to be joined. What he could not tolerate was the waiting and the immense irritation when the winds dropped and the fire boats burned harmlessly in the middle of the bay and then exploded with a loud crack that made the pirates cheer.

It was dawn, the tide suited them high at dawn. The weather suited them at last, a grey mist on the water which would make the pirate muskets uncertain of their aim shooting into greyness, and a brisk onshore wind which should blow the fire boats inwards to the harbour.

‘But hardly a surprise attack,’ Tradescant grumbled, at the pinnace rail. The wind blowing steadily onshore lifted the brim of his hat.

‘The principle is right,’ someone said behind him.

Tradescant thought of his old master’s preference for sound practice over principle, but held his peace. They all watched together as the two barges were rowed to the harbour mouth. The sailors on board lit the fuses to the explosives, burning twists of rope dipped in pitch. No-one could tell how long they would take to burn with any accuracy. It was a brave man who stayed on board a barge that would blow up at any moment to steer it closer and ever closer to enemy shipping.

The two sailors did well. ‘Jump!’ Tradescant muttered under his breath as they went through the harbour mouth and drifted towards the ships, while the waiting English ships could see the sparks at the foot of the powder kegs. Then there were two dark shadows leaping and two splashes in the water, and then an almighty roar as the first barge went up in flames and drifted towards the trapped corsair ships.

But just as it should have collided with the wooden rowing ship there was a sudden lull.

‘The wind!’ Captain Pett yelled in anguish. ‘What the devil has happened to the wind?’

It was nothing, a lull before a storm, but it was enough to ruin the English plans. The fire boats exploded and burned as they should have done as two little torches afloat on the dark water of Algiers harbour, the corsair ships remained moored safe in its lee, and the pirate crews came out on deck with toasting forks and made as if they were frying their bacon for breakfast on the English attack.

‘What do we do now?’ someone asked. ‘Stand down again?’

‘Today we attack,’ Captain Pett said. ‘We follow orders.’

John found his feet were strangely heavy in his boots. There was nothing for him to do until the Mercury was close enough either to shore or to a ship, and then he was to lead a boarding party.