The practicability of submarine navigation was established by the Dutch over two hundred and fifty years ago. Then, as now, its underlying idea, its claim for recognition, was the advantages the system gave in marine warfare. Nor is its battle value overestimated; for such a boat, if successful, exercises an influence that is great in material uses, that is enormous in moral effects. Its development has been slow; for though the problem was solved long ago, no practical results were attained until within the last thirty years. During the late war submarine boats were for the first time employed with such sufficient success that the great maritime powers have considered the type to have an importance which justified investigation. They reached this conclusion because no plan of defence exists which could defy the operations of a weapon that attacks not only matter but mind. There is no danger which sailors will not face; because their environments are always perilous, and their traditions are rich with glorious records of seeming impossibilities overcome by pluck and dash. They are willing always, even against the heaviest odds, to accept any fighting chance. They know that the unexpected is sure to happen. The spirit that made Farragut take the lead of his disorganized line in Mobile Bay still lives; his clarion call of “Damn the torpedoes! Follow me!” is a sea instinct, born of brine and gale, which never dies. Whatever coast fighting or port blockading may demand, sea battles are unchanged. History teaches that ships always closed for action, and that vessels fighting each other from beyond the circling horizons, or hull down, with long-range guns, are the dreams of shore inventors. Guns and ships have changed, but men and the sea are changeless. The fighting distance of to-day is not much greater than it was in Nelson’s or in Perry’s time; and the next naval war will surely prove that battle will be nearly as close as in Benbow’s age, when the gallant tars combed innocuous four-pound shots out of their pigtails, and battered each other within biscuit-throwing distance with deftly shied chocking quoins. It is fortunate, in the interest of good, square fighting, that the operative sphere of submarine boats is limited to coast work. Fortunate, because while the bravery and the grit are the same, the threatening of a danger which cannot be squarely met is apt to benumb the heart of the stoutest. A sailor hates to run; he does not care to fight another day when the chance of the present is open before him; but of what avail are the highest courage and skill against a dull, venomous dog of an enemy who crawls in the darkness out of the deeps, and, silently attaching a mine or torpedo, leaves his impotent foe to sure destruction?