Coast defence, then, implies gun-power and torpedo lines placed as described.  Be it said in passing that only places of decisive importance, commercially or militarily, need such defences.  Modern fleets cannot afford to waste ammunition in bombarding unimportant towns,—­at least when so far from their own base as they would be on our coast.  It is not so much a question of money as of frittering their fighting strength.  It would not pay.

Even coast defence, however, although essentially passive, should have an element of offensive force, local in character, distinct from the offensive navy, of which nevertheless it forms a part.  To take the offensive against a floating force it must itself be afloat—­naval.  This offensive element of coast defence is to be found in the torpedo-boat, in its various developments.  It must be kept distinct in idea from the sea-going fleet, although it is, of course, possible that the two may act in concert.  The war very well may take such a turn that the sea-going navy will find its best preparation for initiating an offensive movement to be by concentrating in a principal seaport.  Failing such a contingency, however, and in and for coast defence in its narrower sense, there should be a local flotilla of small torpedo-vessels, which by their activity should make life a burden to an outside enemy.  A distinguished British admiral, now dead, has said that he believed half the captains of a blockading fleet would break down—­“go crazy” were the words repeated to me—­under the strain of modern conditions.  The expression, of course, was intended simply to convey a sense of the immensity of suspense to be endured.  In such a flotilla, owing to the smallness of its components, and to the simplicity of their organization and functions, is to be found the best sphere for naval volunteers; the duties could be learned with comparative ease, and the whole system is susceptible of rapid development.  Be it remembered, however, that it is essentially defensive, only incidentally offensive, in character.

Such are the main elements of coast defence—­guns, lines of torpedoes, torpedo-boats.  Of these none can be extemporized, with the possible exception of the last, and that would be only a makeshift.  To go into details would exceed the limits of an article,—­require a brief treatise.  Suffice it to say, without the first two, coast cities are open to bombardment; without the last, they can be blockaded freely, unless relieved by the sea-going navy.  Bombardment and blockade are recognized modes of warfare, subject only to reasonable notification,—­a concession rather to humanity and equity than to strict law.  Bombardment and blockade directed against great national centres, in the close and complicated network of national and commercial interests as they exist in modern times, strike not only the point affected, but every corner of the land.