Another development now took place. At this period when disruptive and incendiary shell was proving itself a more powerful agent than solid shot of equal size, both shell and shot gained an enhanced value from the application of rifling to ordnance; moreover, ordnance itself was developing so quickly that each year saw an appreciable increase in the unit of artillery force. This variation in the unit profoundly affected naval architecture. No longer was there a unit of standard and unchanging value, which, when multiplied by a certain number, conveyed a measure of a ship’s offensive power. No longer was the size of a ship a rough measure of its fighting strength; by concentrating power in a few guns, offensive strength could be correspondingly concentrated, if desired, in a small vessel. On the other hand, in view of the sudden accession of offensive strength, the defensive capacities of a ship remaining as before, it was now true that size had become an element of danger, diminutiveness of safety. Hence warships, which had for centuries triumphed in the moral and physical effect of their height and size, suddenly sought to shrink, to render themselves inconspicuous, to take the first step towards total invisibility.
An effect of the same development—of the increasing size of the unit gun, and therefore of the decreasing number of units which a ship could carry—was the mounting of every big gun so as to command as large an arc of fire as possible.
As the final development we note that the steam engine, in endowing the warship with motions far more variable, certain and controlled than those of the sailing ship, called forth tactical ideas quite different, in many respects, from those which governed sea actions in the canvas period. The warship itself is the embodiment of tactical ideas. Hence the design of the steam-propelled warship evolved along a different line from that of the sailing ship.
By the effect and interaction of these developments a complete revolution was compassed in naval architecture; by the progress of artillery and the steam engine, and by the improvement in mechanical processes in general, an entirely new unit of naval force was evolved from the old sailing ship: the mastless, turreted ironclad of the late ’sixties, the precursor of the modern battleship.
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No sooner had the shell gun given proofs of its destructive powers than experiments on the penetrative power of projectiles began to assume importance, and as early as 1838 trials were being made at Portsmouth against a hulk, the result of which, confirming the experiments made by the French with the Pacificateur some sixteen years previously, demonstrated the far-reaching effects of explosive shell against a ship’s side-timbers. Four years later the prime minister was apprised from New York that the Americans had discovered a suitable and adequate protection for ships’ sides; iron plates of three-eighths of an inch in thickness, riveted together to form a compound 6-inch plate, were alleged to have been found ball-proof. On receipt of which intelligence the Admiralty instructed Sir Thomas Hastings, captain of the Excellent, to confirm or disprove by actual trial. Trial was made, but it was reported that no protection was afforded by such plates against the fire of 8-inch shell or 32-pounder shot, even at 200 yards’ range. No defensive remedy could be devised against shell fire, and the only counter-measures deemed practical were of an offensive nature, viz. to mount shell guns as powerful as those of the enemy, and to keep him at a distance by the employment of large and far-ranging solid-shot ordnance.
In the meantime iron, which was not acceptable as a protection, had been accepted as a constructive material for ships. For some years it had been increasingly used for mercantile shipping with satisfactory results. The scarcity of timber and its cost, as well as the positive advantages to be obtained from the use of the much stronger and more plentiful material, had decided the Admiralty in ’43 to build iron warships. Some small vessels were built and, in spite of adverse criticism and alarming prediction, acquitted themselves admirably on service. In ’46 it was resolved, however, to put iron to the test of artillery. An iron steamboat, the Ruby, was used as a target by the Excellent gunners, and the results were unfavourable; the stopping power of the thin metal was small, and the balls which went clean through the near side wrought extensive damage on the opposite plates. In ’49 trials were made with stouter plates with more promising results: a report favourable to iron as a protection for topsides was made. But in ’51, as the result of elaborate trials made against a “mock up” of the side of the Simoon, the previous conclusions were reversed. Iron was condemned altogether as unsuitable for ships of war. “The shot and shell,” reported Captain Chads, “on striking are shivered into innumerable pieces, passing on as a cloud of langrage with great velocity,” and working great destruction among the crew. Nor was a combination of wood and iron any better. In fact the report claimed that, as regards the suitability or the unsuitability of iron, these experiments might be deemed to set the question at rest. The experience of the French had apparently been somewhat similar to our own. In both countries the use of iron for warships received a sudden check and, in England at any rate, the idea of unarmoured wood was once again accepted. In both countries the opinion was widely held that iron was unsuitable either for construction or protection, and that the view of General Paixhans, that vessels might be made proof even against shells by being “cuirassées en fer,” was preposterous and impracticable.[161]
Potentially, as it now seems, wooden sailing ships were so weak in defensive qualities that the new artillery, if only it could be adequately protected, had them at its mercy. Actually it required the rude test of war to establish the unpalatable truth. In November, 1853, such proof was given. At Sinope a squadron of Turkish frigates armed with solid-shot guns was almost blown out of the water by shell fire from a powerful Russian squadron; the latter were practically uninjured, while the Turkish fleet was set on fire and a terrible mortality inflicted among the crews in a short time. General Paixhans, who had lived to see his invention fulfil in actual warfare his early predictions, was able to emphasize, in the columns of the official Moniteur, the arguments against large ships and the advantages which would accrue to France especially by the subdivision of force and the substitution of small protected steamers armed with heavy guns for the existing wooden ships-of-the-line. The concentrated fire of a few such steamers would overpower the radiating fire of the largest three-decker.
The type of naval warfare imposed on the allies in the Crimean War lent special force to Paixhans’ arguments. For the attack of fortresses and coasts whose waters were exceptionally shallow it was at any rate clear that the orthodox form of warship, unarmoured, of large size and of deep draught, was of very limited value. Some special form was necessary; France made a rapid decision. Napoleon III issued an order for the construction of a flotilla of floating batteries, light-draught vessels capable of carrying heavy shell guns and of being covered with iron armour strong enough to resist not only solid shot but the effects of explosive shell.
The idea of armouring ships was, of course, not novel. Armour of sorts had been utilized from antiquity; in the days when the shields of the men-at-arms were ranged along the bulwarks of the war galleys; in the Tudor days when the waists of ships were protected by high elm “blinders,” and when Andrea Doria’s carrack was so sheathed with lead and bolted with brass that “it was impossible to sink her though all the artillery of a fleet were fired against her.” In the eighteenth century the French themselves had attempted to clothe floating batteries with armour, not indeed against shells but against red-hot shot. In 1782 they had devised, for the attack on Gibraltar, six wooden floating batteries which, with their armament, were protected by a belt of sand enclosed in cork and kept moist with sea water. But this experience had been disastrous. The sand-drenching apparatus failed to act, and the batteries were almost totally destroyed by fire.