Meanwhile a smaller single-turret ship, the _Conqueror_, had been built, an unwieldy-looking craft which went by the name of the "half-boot" from the resemblance her general outline had to that useful article of military equipment. But she seems to have met with the approval of the Admiralty, since an improved sister-ship, the _Hero_, was launched about five years later. These ships probably suggested the very much larger ones, _Victoria_ and _Sans Pareil_, each of which, on a displacement of 10,470 tons only, carried a couple of 111-ton guns of 16·25-inch bore in a single turret--that is to say, as their main armament. They had also a 10-inch gun aft, and a dozen 6-inch breech-loading guns. These formed what is called her "secondary battery". The provision of such batteries marks a step in the evolution of war-ship construction which is very noteworthy. The bigger and bigger guns carried by battleships necessitated stronger and stronger armour. In spite of improvements in quality and manufacture the weight of armour tended constantly to increase. The area covered had therefore to be more and more restricted. To carry all this weight of guns and armour comparatively large ships were necessary, and a great part of their sides had to go without any protection at all. Their flotation might be preserved--against attack by gun-fire--by the combination of armoured belt and sloping armoured decks which had by now become almost universal. But it was obvious that the unarmoured portions of the ship above water could be torn to pieces by the fire of comparatively light weapons. This led to the installation of "secondary batteries" of 4-, 5-, and 6-inch guns, for the purpose of attacking an enemy's ship in this way and of neutralizing his attack by keeping down the fire of _his_ secondary batteries. [Illustration: _Photo. West & Son, Southsea_ A MONSTER GUN WHICH IS NOW OBSOLETE The 111-ton gun on the old _Benbow_, which was very slow of fire and whose life was estimated at little more than 70 rounds.] The development of torpedo-attack brought about the Whitehead automobile torpedo, and the improvements in the speed and construction of destroyers and torpedo-boats caused also the introduction of "auxiliary batteries" of rapid-firing 3- and 6-pounder-shell guns. The machine-guns firing rifle bullets, and, later on, small steel shot, were found to have no "stopping-power" against torpedo-craft, and more powerful weapons became imperative. The tragic end of the _Victoria_, which cost the nation, not only a fine ship, but the lives of the greater portion of her crew, and that very talented naval commander, Sir George Tryon, is a well-known tragedy of the sea, and there is little doubt that the enormous weight forward of her huge turret and guns, with nothing aft to counterbalance it, was one of the causes contributing to the completeness of the catastrophe.