But now, although experiments with iron-plated ships had been the reverse of satisfactory, data were to hand which showed that, if used in sufficient thickness, iron plates were capable of withstanding the disruptive effects of shell. At Vincennes trials had been made, between 1851 and 1854, with various thicknesses and dispositions of iron; with plates four to five and a half inches thick, with compound plates, and with plates supported on a hard wood lining eighteen inches thick; of all of which the thick simple plates had proved the most effective. So the five floating batteries ordered for work in the Crimea were covered with 4-inch iron plates backed by a thick lining. Sixty-four feet long, 42 feet in beam, drawing about 18 feet of water, armed with sixteen 56-pounder shell guns and equipped with auxiliary steam machinery for manœuvring, their construction was hastened with all possible speed. By October, ’55, three of them, the Dévastation, Tonnante, and Lave, had joined the allied flags, and on the 17th of that month they took a principal part in the bombardment of Kinburn. Their success was complete. Although repeatedly hit their iron plates were only dented by the Russian shot and shell. “Everything,” reported the French commander-in-chief, “may be expected from these formidable engines of war.” Once again the arguments of Paixhans for armoured war vessels had been justified; the experience gained with iron armour at Kinburn confirmed that gained with shell guns at Sinope. France at once proceeded to apply these lessons to the improvement of her navy proper.
In England, on the other hand, no great impression was created either by shells or by iron protection. A comfortable faith in our fleets of timber-built ships persisted; and, with regard to policy, as it had been with shell guns, and with steam propulsion, so it appeared to be with armour; the national desire was to avoid for as long a time as possible all change which would have the effect of depreciating the value of our well-tried material. At the same time it is remarkable how small an effect was conveyed to expert opinion, both here and in America, by the events of the Crimean War. In the years immediately following the war some notable technical works were published: Dahlgren’s Shell and Shell Guns, Read’s Modifications to Ships of the Royal Navy, Grantham’s Iron Shipbuilding, Sir Howard Douglas’ Naval Warfare with Steam, and Hans Busk’s Navies of the World. From these works and from the press and parliamentary discussions of the day it is evident that, outside France, the impressions created were vague and conflicting. The main lesson conveyed was the great tactical value of steam propulsion. The reports laid no emphasis on shells, and so scanty was the information concerning them that it was very difficult to appraise their value. Their effect at Sinope was disguised by the overwhelming superiority of the Russian force, which rendered the result of the action a foregone conclusion; on another occasion (at Sebastopol) shells fired at long range were reported to have failed to penetrate or embed themselves in a ship’s timbers. Commander Dahlgren was uncertain, in the absence of fuller information, whether shells had justified their advocates or not. Nor was Grantham impressed by the French floating batteries. “One only of these vessels,” he incorrectly says, “was thus engaged, but then not under circumstances that gave any good proof of their efficiency, as the fire was distant and not very heavy.”
So no violent change in our naval material followed as the immediate result of the war. Only in the matter of light-draught gunboats and batteries tardy action was forced on the authorities by public opinion. Although iron had been condemned for warship construction iron ships had been built in the years preceding the war in considerable numbers for foreign governments; the firms of Laird and Scott Russell had built in 1850 powerful light-draught gunboats for Russia, and in the same year Russia had ordered from a Thames firm an iron gunboat whose novel design had been brought to the notice of the Admiralty. But these craft were intended for the defence of shallow waters, and nothing analogous to them was considered necessary for the British navy. The exigencies of the war demonstrated in the course of time the value of these light-draught vessels. Still there was long hesitation; though the French government pressed on us their advantages, and presented our minister with the plans of their own floating batteries. The disappointment of the Baltic expedition, however, and the realization that the powerful British fleet which in the summer of ’54 had set out to reduce Cronstadt had done nothing but prove the inherent unsuitability of large ships-of-the-line for the attack of fortresses in shallow waters, gave rise to a loud demand in the press that gunboats should be built. Several were accordingly laid down. The first of these were found to be too deep, but others of lighter draught were designed and by the autumn of ’55 sixteen were ready; and these, together with some dockyard lighters which had been fitted as mortar vessels, joined a flotilla of French floating batteries in the Baltic and effectually bombarded Sveaborg. As the war progressed the value of ironclad gunboats became more fully appreciated. A large number was ordered, but most of them were only completed in time to fire a grand salute in honour of the proclamation of peace.[162]
Apart from the building of these gunboats innovation was avoided. Unarmoured wooden ships, equipped with a mixed armament of shot and shell guns, continued to be launched and passed into commission, and it was only after France had constructed, at Toulon in ’58, an iron-encased frigate, that England unwillingly followed suit, convinced at last that a reconstruction of her materials could no longer be averted.
La Gloire, the iron-belted frigate, was the direct result of the lessons gained from the floating batteries in the Russian war. After Kinburn the French naval authorities took up the study of how to apply armour to sea-going ships. Was it possible to embody in a fighting unit sea-going capacity, high speed, great offensive power, in addition to the defensive qualities possessed by the slow, unwieldy batteries? Could such a weight as iron armour would entail be embodied in a ship design without loss of other important qualities? It was concluded that, while it would be impossible to cover the sides completely, it would be possible to protect the surfaces near the water-line, under cover of which all the ships’ vital parts could be secreted. A great increase in defensive power would thus be obtained. Before developing a plan in detail it was decided to carry out further armour trials, and solid iron plates of 4½ inches thickness were fired at with English 68-pounders and French 50-pounders, with solid balls and with charged shells. The results were satisfactory, so these plates were adopted as the standard of armour protection. To the design of M. Dupuy de Lôme the first ironclad frigate was constructed from a fine two-decked ship, the Napoleon, which was cut down, lengthened, and armoured from stem to stern. The result was the celebrated Gloire. She was followed shortly afterwards by two sister vessels. And then, in order to obtain a direct comparison between timber-built and iron ships, an armoured iron frigate, the Couronne, was also built. The three wooden ships were given a complete belt round the water-line of 4½ inches of iron; the Couronne had compound armour—3-inch and 1½-inch iron plates separated from each other and from the iron stem-plating by wood lining 6 inches in thickness. The armament of all four frigates consisted of thirty-six 50-pounder shell guns, carried low. They were given yacht masts and equipped with propelling machinery designed to give them 12 knots speed.
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The naval position of England at this time was the reverse of satisfactory. Comparing the material resources of the two great maritime rivals, it came to be noted with surprise that France, taking advantage of the development of steam propulsion during the decade, had actually drawn level with England in the numbers of steam warships available and in their aggregate motive horse-power. The French had submitted to great financial outlay on account of their navy. In this country a reaction, following the large and partially ineffective expenditure incurred in the Crimean War, had dried up the sources of supplies and stunted constructional development; there was little to show for the money spent on such works as the enlargement of docks and on the extensive new factories and docks established at Sheerness and Keyham. Apprehension was widespread when the intelligence of the building of the iron-sided ships was received, and this apprehension developed when whispers reached Westminster of a huge prospective programme meditated by France. To allay the panic a parliamentary committee was formed to inquire into the relative strength of the two navies; and their report, published in January, 1859, made bad reading. Comparing the steam navies—for, the committee reported, sailing ships could not be opposed to steamships with any chance of success—France and England each had afloat the same number of line-of-battle ships, viz. twenty-nine; and as regards frigates France had thirty-four to England’s twenty-six! This did not include the four frégates blindées laid down by France, which would be substitutes for line-of-battle ships, which were being built with the scantling of three-deckers, and which were to be armed with thirty-six heavy guns, most of them 50-pounders throwing an 80-pound hollow percussion shell. “So convinced do naval men seem to be in France,” note the committee, “of the irresistible qualities of these ships, that they are of opinion that no more ships-of-the-line will be laid down, and that in ten years that class of vessel will have become obsolete.” The position is bad enough; yet so bewildered are our experts by the radical developments of the rival navy, so difficult appears the problem of countering the French designs by any new and well-studied procedure, that all that the committee can recommend is the accelerated conversion of our remaining sailing ships to steam. The committee realize that naval architecture, and still more naval artillery, is in a state of transition, and that the late invention of Armstrong’s gun “may possibly affect even the size and structure of ships of war.”
It is not possible, however, for a country desirous of maintaining its maritime supremacy to wait upon perfection in the manner implied as the policy of the parliamentary committee. Some drastic and immediate action was necessary, to redress the advantage accruing to France from the possession of the Gloire and her sister frigates. Such action was duly taken; but before proceeding to examine this action it will be necessary to revert for a moment to a consideration of iron. We have already sketched the evolution of iron as a protective covering for warships; we must now glance back and briefly trace its progress as a constructive material.
Iron vessels had appeared on the canals of England in the latter part of the eighteenth century. In 1815 a pleasure boat of that material had sailed on the River Mersey, attracting crowds of people whose credulity had been severely strained by the statement that an iron ship would float. Admiral Napier had manifested an early interest in iron ships; in 1820, in partnership with a Mr. Manby, he had constructed the first iron steamer, the Aaron Manby, and navigated it from London up the Seine to Paris, where in ’22 it attracted considerable attention. From this date onwards iron vessels increased in number. In ’39 the Nemesis and Phlegethon were built by Mr. Laird for the East India Company, and in the China war of ’42 these gunboats played a conspicuous and significant part. The grounding of the Nemesis in ’40 on the rocks of Scilly afforded early evidence of the value of watertight bulkheads (a Chinese invention) when embodied in an iron hull.
As the size of ships increased, the disabilities attaching to the use of timber became more and more evident. Though braced internally by an elaborate system of iron straps, knees, and nutted bolts in iron or copper, the large timber-built ship, considered as a structure, was fundamentally weak; in fact the presence of the straps and ties contributed in no small degree to its inability to withstand continuous stress. The fastenings did not accord with the materials which they fastened together, and the wood was relatively so soft that when a severe strain arose a general yielding took place, the boltheads sinking into the wood and causing it to give way to the pressure thrown locally upon it. As tonnage increased the metal fastenings grew more and more conspicuous, the ship became a composite structure of wood and iron, with the result that uniformity of elasticity and strength was lost and the stresses, instead of being distributed throughout the structure, tended to become localized at certain points. “The metallic fastenings of a timber-built ship act to accelerate her destruction so soon as the close connection of the several parts is at all diminished.” So in 1840 wrote Augustin Creuze, a graduate of the disbanded school of naval architecture and one of the most gifted and eminent men of his profession at that day.