The fireships’ self-discharging guns scattered the defenders and let the ships through.

Evidence

These flaming monsters were no mere fishing-smacks, stuffed with brush and straw, to be fended off with oars. Getting a grapnel to hold on them, swinging them around and towing them on to the beach would be a feat of seamanship requiring nerve and brawn and split-second timing, for the line was driving along so fast, pushed by a strong wind, a spring tide and the set of the Channel current all working together, that it would cover its whole course in a few minutes. Apparently the first pair of pinnaces executed their manœuvre smartly enough, for the next morning the charred ribs of two fire-ships lay smouldering well short of the Spanish anchorage; but, a few seconds later, just as the next pair of pinnaces came into position and when, one must assume, the men standing in their bows were ready to throw their grapnels, the double-shotted guns heated now almost white-hot began to go off, spraying their shot at random over the water and by the force of their recoil sending up a fountain of sparks to be blown down among the boats. Startled, the pinnaces sheered off, there was a moment of tangled confusion; and in that moment the six remaining ships swept past and bore down on the anchored fleet, the sound of their exploding guns heard above the roar of the flames and the fountains of sparks shooting skyward. There could be no doubt. Here, once more, were the deadly hellburners of Antwerp. — Garrett Mattingly, The Defeat of the Spanish Armada, 732

Categorization

• FICTION: White-hot guns firing by the heat of the flames, shooting random shot and fountains of sparks - perfect technical detail for staging the attack.
• XREF: This is the direct execution of the fireship tactic Drake would later replay at Cadiz - the reader’s core thread.
• corroborated: 2 independent passages support this claim — Garrett Mattingly, The Defeat of the Spanish Armada, 732