Next came the _Enterprise_, a still smaller ship. In the _Bellerophon_, as we have seen, there was no bow fire possible from the central battery; in the _Enterprise_ this was obtained by piercing the athwartship bulkheads of the battery with ports, and substituting movable for fixed bulwarks. The same arrangement was developed in the _Pallas_ and _Penelope_, in which ships the arc of fire of the corner guns of the battery was further extended by the device of indented sides. Then came the _Hercules_, generally like the _Bellerophon_ but with indented sides and, as a novelty, alternative ports in the battery armour by means of which the corner guns could be trained, on revolving platforms, to fire either on the beam or nearly in line with the keel; a system which presented an obvious disadvantage in requiring twelve ports for eight guns. In the _Kaiser_ class, designed by Sir Edward Reed shortly afterwards for the German government, this disadvantage was obviated by the expedient of forming ports in facets of the battery set at forty-five degrees with the keel-line, and by muzzle-pivoting guns. Both in the _Bellerophon_ and the _Hercules_ axial fire had only been obtained by the provision of special batteries, at the bow and stern, of partially protected guns. Now, this accumulation of weight at the extremities was a feature viewed with disfavour by naval opinion; moreover, these bow batteries did not meet the ever-growing demand for a considerable ahead fire. So in the _Sultan_, which carried a central-battery armament similar to that of the _Hercules_, an upper deck armoured battery was embodied, superposed on the after end of the main deck battery and carrying guns which gave both astern and beam fire; while, for bow fire, two 12-ton guns were mounted in the forecastle, but without any protection. The central-battery system had now to sustain the greatest attack that had yet been made upon it by the advocates of centre-line turrets. The position of the central-battery school was already somewhat shaken; ordnance had grown to a weight and power which justified the main argument of the turret advocates; Lissa had just shown the importance of being able to concentrate on any one bearing a maximum of offensive power. Controversy raged hotly on the relative merits of turret and central battery.