The third cause is the acquisition by the flotilla of battle power. It is a
feature of naval warfare that is entirely new.[10] For all practical
purposes it was unknown until the full development of the mobile torpedo.
It is true that the fireship as originally conceived was regarded as having
something of the same power. During the Dutch wars--the heyday of its
vogue--its assigned power was on some occasions actually realised, as in
the burning of Lord Sandwich's flagship at the battle of Solebay, and the
destruction of the Spanish-Dutch fleet at Palermo by Duquesne. But as the
"nimbleness" of great-ships increased with the ripening of seamanship and
naval architecture, the fireship as a battle weapon became almost
negligible, while a fleet at anchor was found to be thoroughly defensible
by its own picket-boats. Towards the middle of the eighteenth century
indeed the occasions on which the fireship could be used for its special
purpose was regarded as highly exceptional, and though the type was
retained till the end of the century, its normal functions differed not at
all from those of the rest of the flotilla of which it then formed part.

[10] But not without analogous precedent. In the later Middle Ages small
craft were assigned the function in battle of trying to wedge up the
rudders of great ships or bore holes between wind and water. See Fighting
Instructions (Navy Record Society), p. 13.

Those functions, as we have seen, expressed the cruising idea in its purest
sense. It was numbers and mobility that determined flotilla types rather
than armament or capacity for sea-endurance. Their primary purpose was to
control communications in home and colonial waters against weakly armed
privateers. The type which these duties determined fitted them adequately
for the secondary purpose of inshore and despatch work with a fleet. It
was, moreover, on the ubiquity which their numbers gave them, and on their