Now, this being the object of a military blockade, its methods will be subordinated to that object. In the days of sailing ships the method which commended itself to the best naval authorities of the time was to have an inshore squadron, consisting mainly of frigates and smaller craft, but strengthened if necessary by a few capital ships, generally two-deckers, closely watching the entrance to the port, but keeping outside the range of its land defences. This was supported at a greater distance in the offing by the main blockading fleet of heavier ships of the line, cruising within narrow limits and keeping close touch with the inshore squadron. Such a method is no longer practicable owing to the development of steam navigation, and to the introduction into naval warfare of the locomotive torpedo, and of special vessels designed to make the attack of this weapon extremely formidable and extremely difficult to parry. The inshore squadron of the old days was liable to no attack which it could not parry if in sufficient force, and if too hardly pressed it could always fall back on the main blockading fleet, which was unassailable except by a corresponding force of the enemy. The advent of the torpedo and of its characteristic craft has changed all this. No naval Power can now afford to place its battleships at a fixed station, or even in close touch with a fixed rendezvous, which is within reach of an enemy's torpedo craft. The torpedo vessel which operates only on the surface is, it is true, formidable only at night; in the daytime it is powerless in attack and extremely vulnerable. But the submarine is equally formidable in the daytime, and its attack even in the daytime is far more insidious and difficult to parry than that of the surface torpedo vessel is at night. The effective range of the surface torpedo vessel is thus, for practical purposes, half the distance which it can traverse in any given direction from its base between dusk and dawn--say from one hundred to two hundred miles, according to its speed and the season of the year. The speed of the submarine is much less, but it can keep the sea for many days together, sinking beneath the surface whenever it is threatened with attack. It can also approach a battleship or fleet of battleships in the same submerged condition, and experience has already demonstrated that its advance in that condition to within striking distance is extremely difficult to detect. Moreover, even if its presence is detected in time, the only certain defence against it is for the battleship to steam away from it at a speed greater than any submarine has ever attained or is likely to attain in the submerged condition. It should further be noted that torpedo craft engaged in offensive operations of this character are not confined to the blockaded port as a base. Any sheltered anchorage will serve their purpose, provided it is sufficiently fortified to resist such attacks from the sea as may be anticipated.