The guardboat had been hidden by the smoke, but he could hear voices yelling in the darkness and then the sudden blare of a trumpet from the direction of the fortress.

The Hekla’s third shot overreached, and he heard the splintering crash of stonework and guessed it had hit the causeway or part of the islet below the walls. The marines would be using their shuttered lanterns to signal the news to Inch, and fresh adjustments would have to be made to the charges or elevation before another attempt.

Allday said, “Mr Sawle is pulling away now.” He sounded relieved. “He cut it fine, an’ no mistake!”

Bolitho called, “Pass the word, Mr Bickford! We are about to attack!”

No need to be quiet now. There was enough clamour from the fortress walls to awaken the dead as the dazed Spaniards ran to their defences. Some might have guessed what was being used against them, others would be too terrified to think as the fortress shook to the battering from Inch’s mortars.

It was at that moment Sawle’s charge exploded. Bolitho saw the low entrance erupt in a great gushing tongue of fire, watched with fixed fascination as a small tidal wave surged out from below the wall to hurl Sawle’s cutter on to its beam ends, spilling men and oars into the sea in a kicking tumult, like a whaleboat before a wounded narwhal.

As he drew his sword and waved it towards Bickford he saw part of the upper rampart fall slowly across the belching flames, taking with it an iron-wheeled cannon and a length of heavy chain, which he guessed was part of the portcullis hoisting gear.

“Right, lads! Give way together!” He almost fell as the boat surged forward beneath him, feeling the hot smoke fanning above his head to mark the power of the last detonation.

The upended cutter passed in the gloom, and here and there he saw a pale face, thrashing arms and legs, to show that some at least had survived the explosion.

Then he forgot everything but what he had to do, as like a gaping mouth, the blasted portcullis protruding from the breached wall like rotten teeth, the opening was right ahead and then over the bows.

A musket ball slammed against the gunwale, and somewhere a man screamed in sudden agony.

He waved his sword above his head and yelled, “Pull, lads!”

The barge seemed to be hurling itself through the smoke at a tremendous speed. He saw pieces of scorched woodwork floating on the surface, and then two grotesque sternposts of what must be old galliasses which the fortress had once used to defend the coast against pirates. Oars crashed against wood and stone alike, and he saw Bickford’s boat following dangerously close astern, the oarsmen momentarily illuminated as someone fired a pistol from the wall above.

“Easy!” Allday’s voice was almost lost as an explosion shook the air to announce the arrival of another of Inch’s bombshells. “Toss your oars!”