In sailing days, of course, this power of the supporting ship was weak owing to the imperfection of the means of distant communication between ships at sea and the non-existence of such means beyond extreme range of vision.  But as wireless telegraphy develops it is not unreasonable to expect that the strategic value of the supporting or intermediate ship will be found greater than it ever was in sailing days, and that for dealing with sporadic disturbance the tendency will be for a cruiser line to approximate more and more in power of resistance to that of its strongest unit.

For fleet service a cruiser’s power of resistance was hardly less valuable; for though we speak of fleet cruisers as the eyes of the fleet, their purpose is almost equally to blindfold the enemy.  Their duty is not only to disclose the movements of the enemy, but also to act as a screen to conceal our own.  The point was specially well marked in the blockades, where the old 50-gun ships are almost always found with the inshore cruiser squadron, preventing that squadron being forced by inquisitive frigates.  Important as this power of resistance in the screen was in the old days, it is tenfold more important now, and the consequent difficulty of keeping cruisers distinct from battleships is greater than ever.  The reason for this is best considered under the third and most serious cause of complexity.

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