By the end of 1911 eight boats of the D class had been launched. It was originally intended to build a total of nineteen of this class, but meanwhile an improved boat of the E type was evolved. The E class are 177ft. long, with a submerged displacement of 800 tons or thereabouts, and four 21-inch tubes. They are fitted with wireless. Their special feature, however, is the fitting of guns, as a regular and integral part of the design. The first submarine to mount a gun was D4, in which a special 12-pounder was experimentally mounted, so that it could be housed when the boat was submerged; for later boats two guns were decided on. The E class were followed by an F class--and a variety of other boats, most of which have been completed since the war began and concerning which it is obviously undesirable to say anything whatever. Guns for submarines were expected to appear sooner than they actually did. At an early stage it was foreseen that, once radii developed, submarines were likely enough to find themselves in contact with hostile submarines and to need something to attack them with. The original idea of the submarine as “the weapon of the weaker Power” soon went the same way as did a similar idea about torpedo boats at their first inception. In torpedo-boats it was at once self-evident that, whatever the value of the torpedo boat, the stronger Power was able to build far more than the weaker, and to annihilate accordingly. For a time the submarine seemed to defy this law. It was fatuously hoped that “submarines cannot injure hostile submarines”; and that the “torpedo boat is the answer to the torpedo boat” would not have as sequel “the submarine is the answer to the submarine.” [Illustration: _Photo_] [_Stephen Crabb. Southsea._ SUBMARINE E 2.] It may well be in the womb of the future that submarines to-morrow, or perhaps to-day, may be what the ironclad was yesterday or the day before. The submarine battleship may appear and render obsolete the “Dreadnought” of to-day! But nothing can alter the cardinal fact that, given equal efficiency, the Power with most such craft must win, and that, given an inferior efficiency, defeat may be looked for as the natural corollary on lines entirely unconnected with whether the “capital ship” is of a type that floats only or one that can be submerged at will. Tactics may alter, the means may alter, and the most obvious instruments of naval strategy may do the same. But nothing whatever can affect the bedrock truth that, given equal efficiency, “numbers only can annihilate.” Given the “equal efficiency” nothing else really matters!