Here we may briefly note the conversion of the timber-built fleet. In ’57 Captain Moorsom had submitted a scheme of cutting down ships to a short height above the water-line and using the weight thus gained to provide an armour belt. Sir Charles Napier had advocated a similar policy in parliament. As soon as the necessity for armour was accepted this policy was adopted; not only were the resources of the private ship-yards bent to the building of a fleet of new iron warships, but the best of the old navy was metamorphized in the royal dockyards by the process of the _razee_: the cutting down of two-deckers and their conversion into iron-belted frigates. By these exertions France was soon outstripped in the struggle. For a long time she clung to wooden ships, though in ’62 she adopted iron for upper works; and of such ships, of wooden bottoms but of iron above the water-line, she built a fleet “possessing only one possible merit--uniformity; which the new English construction lacked.” The combination of heavy steam machinery and wooden hulls was the cause of continuous difficulties; the growth of artillery rendered the ships obsolete almost before they were built.
By the time the _Warrior_ and her sister ships were afloat the great struggle between armour and artillery was well in progress. It was a struggle which was to lead to unsuspected developments in naval architecture.
For the moment, and in the presence of the new iron-built ironclads, the gun was at its lowest point of effectiveness. But rifling had conferred new powers on it, and the greatest efforts were being put forth to improve its position. As it grew rapidly in size and power, naval experts were faced with a succession of problems of extraordinary difficulty. Two things were in question: both the type and the disposition of gun best suited for a warship’s armament.
With regard to type, the adoption of armour inevitably gave a set-back to the value of the shell gun. Shells, which would rend and set on fire a wooden ship, would not pierce armour or inflame iron plates; of which facts Hampton Roads afforded a demonstration. It seemed clear also from that incident, to experts in this country and in France, that no extension of the Paixhans principle was likely to compete with armour in the future. The system of shell fire of General Paixhans, like the shot system of the inventor of the carronade, had relied on low muzzle velocities and curved trajectories, to effect its purpose. His shells were for lodgment rather than penetration, and did not gain their effect by their kinetic energy; and in view of this their inventor had himself conceived the use of iron armour as the very means whereby they might be countered. Nevertheless the Americans had been strongly attracted by the Paixhans principle, and with their Dahlgrens and Columbiads had extended it in practice to embrace the use of guns of the largest calibres. The action between the _Monitor_ and the _Merrimac_ did nothing to shake their faith in this class of ordnance. Subsequent experiments appeared to confirm the national predilection; and one of their writers, in giving credit to the navy chiefs for adhering to the principle of the large smooth-bore gun, recorded that the small-bore-and-high-velocity theory had received its quietus by the utter demolition of a 6-inch plate by a ball from a 15-inch gun at Washington in February, 1864.[165] In France and England it was held, and held rightly, that high velocities were necessary for the attack of armour.