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 power of dealing with unarmed or lightly armed vessels, that we relied for our first line of defence against invasion.  These latter duties were of course exceptional, and the Navy List did not carry as a rule sufficient numbers for the purpose.  But a special value of the class was that it was capable of rapid and almost indefinite expansion from the mercantile marine.  Anything that could carry a gun had its use, and during the period of the Napoleonic threat the defence flotilla rose all told to considerably over a thousand units.

Formidable and effective as was a flotilla of this type for the ends it was designed to serve, it obviously in no way affected the security of a battle-fleet.  But so soon as the flotilla acquired battle power the whole situation was changed, and the old principles of cruiser design and distribution were torn to shreds.  The battle-fleet became a more imperfect organism than ever.  Formerly it was only its offensive power that required supplementing.  The new condition meant that unaided it could no longer ensure its own defence.  It now required screening, not only from observation, but also from flotilla attack.  The theoretical weakness of an arrested offensive received a practical and concrete illustration to a degree that war had scarcely ever known.  Our most dearly cherished strategical traditions were shaken to the bottom.  The “proper place” for our battle-fleet had always been “on the enemy’s coasts,” and now that was precisely where the enemy would be best pleased to see it.  What was to be done?  So splendid a tradition could not lightly be laid aside, but the attempt to preserve it involved us still deeper in heresy.  The vital, most difficult, and most absorbing problem has become not how to increase the power of a battle-fleet for attack, which is a comparatively simple matter, but how to defend it.  As the offensive power of the flotilla developed, the problem pressed with an almost bewildering intensity.  With every increase in the speed and sea-keeping power of torpedo craft, the problem of the screen grew more exacting.  To keep the hostile flotilla out of night range the screen must be flung out wider and wider, and this meant more and more cruisers withdrawn from their primary function.  And not only this.  The screen must not only be far flung, but it must be made as far as possible impenetrable.  In other words, its own power of resistance must be increased all along the line.  Whole squadrons of armoured cruisers had to be attached to battle-fleets to support the weaker members of the screen.  The crying need for this type of ship set up a rapid movement for increasing their fighting power, and with it fell with equal rapidity the economic possibility of giving the cruiser class its essential attribute of numbers.