The Inflexible was followed by its smaller derivatives, the Ajax and Agamemnon, Colossus and Edinburgh, and by the Conqueror, an improved Rupert, with a single turret. Movement was in the direction of smaller displacements and less armour; construction was influenced at this time more by Italian than by French practice.
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All through this transitional decade, 1870–80, experience and various new developments were imperceptibly causing a gradual change of opinion as to what constituted the best type of battleship. At no period, perhaps, was the warship more obviously a compromise, at no time were the limitations of size and weight more keenly felt. So many considerations interacted with one another, so conflicting were the claims made of the naval architect, that it appeared indeed almost impossible to embody them in a satisfactory design. (And yet nothing is more remarkable than the unanimity with which designers, given certain conditions, arrived at the same final result: the Duilio and the Inflexible are a case in point.) Whatever the design might be, it was open to powerful criticism. And the chief part of this criticism was directed, as we have seen, against the use and disposition of the armour.
In ’73 Mr. Barnaby had questioned the wisdom of expending a large weight in the protection of turrets. Three years later Commander Noel, in a Prize Essay, was advocating unarmoured batteries, with a view to multiplying the number of battery guns, utilizing for offence the weight thus saved. In ’73 Mr. Barnaby had argued that the stinting of armour on the hull in order to thicken it on the battery would drive the enemy to multiply his light and medium machine-guns. Within a few years warships were bristling with Gatling and Gardner, Nordenfelt and Hotchkiss guns, which by their presence gave a new value to armour, however thin. Mr. Froude, too, in his experiments in connection with the Inflexible, brought into prominence the advantage which thin armour on a ship’s ends conferred on her stability. The idea of substituting cellular construction for armour was proving attractive. While the French continued to favour the complete water-line belt, the Italians went to the limit in the Italia and Lepanto, in which the water-line was left entirely unprotected by side armour. Such armour as was carried was embodied in the form of a protective deck, a feature found above water and in conjunction with a side belt in our Devastation class, and under water and without side armour in the Inflexible and smaller contemporary ships. The protective deck, which covered the vitals of a ship and deflected shot and shell from its surface, was a device which found increasing favour with naval architects. It was advocated by the Committee on Designs in ’71 as possessing important advantages over a similar weight of side armour. If placed at some distance below water it formed the roof of a submerged hull structure which was immune from damage by gun-fire, the sides of this hull being protected sufficiently by sea-water. If, as was subsequently done, the protective deck were placed at a small distance above water, and if the sides of it were bent down so as to meet the ship’s sides at a distance below water beyond which a shot was unlikely to penetrate, the deck offered other advantages: the vital machinery, though now partly above water, was still protected, the sloping parts of the deck being able to deflect shots which would have penetrated a much thicker vertical plate; moreover, if the ship’s sides were riddled in action, the protective deck still preserved a large portion of the water-line area intact, and thereby secured her lateral stability.
The ram was still in favour, but opinion was slowly changing as to the necessity for bow-fire. “It is my impression,” wrote Commander Noel in ’76, “that too great a value was attached by some of the authorities, two or three years ago, to bow-fire; and that the manœuvring of a fleet in action will be more for the purpose of using the ram effectually, and the guns in broadsides on passing the enemy.” The firing of the heavy guns in the approach to ram was considered undesirable, owing to the obscuring of the scene by smoke. In short, bow-fire was not of primary importance, and the disposition of armament which sought to obtain a concentration of bow-fire at the expense of broadside fire was based on a false principle. Commander Noel advocated a broadside ship, of moderate tonnage, with an unarmoured battery of moderate-size guns, with an armour belt round her water-line of 10-inch armour tapering to 5 inches forward and aft, and backed by wood and coal. Watertight subdivisions he proposed as a defence against the ram and the torpedo.
As the decade progressed the navy and naval affairs were less and less a subject of public interest. The design of warships continued to be discussed by a small circle, but the Board, alive to the transitional nature of the citadel ships, and under the influence of a national movement for retrenchment and economy, had almost ceased to build. In the three years ’76, ’77, and ’78 England laid down only two armoured battleships, while France laid down a dozen. In ’78 four foreign ships building in this country were hastily purchased on a Vote of Credit. But by 1880 the French armoured navy was once more equal in strength to that of England.
The gun, by its rapid evolution, was blocking design. The long debates over sails and steam had been settled; it was now the achievement of powerful breech-loading guns of large and small calibre which threw all existing ideas of warship design into the melting-pot. It became known that the French at last possessed efficient breech-loading guns; and artillerists showed that, in spite of the inconvenience of long-barrelled guns in ships, long barrels and slow-burning powder were necessary if greater powers were to be developed, and that our short-barrelled muzzle-loaders were already becoming obsolete. In the summer of ’79 public interest was aroused by the arrival at Spithead of some Chinese gunboats built by the firm of Armstrong. These gunboats each carried two 12-ton breech-loading guns mounted on centre pivots, one forward and one aft: guns so powerful and efficient compared with any mounted in the Royal Navy, that the possibilities of the diminutive craft were instantly appreciated. The contest between B.L. and M.L. was approaching a climax. The 100-ton M.L. gun was undergoing proof at Woolwich. In August a committee of naval officers visited Germany to witness and report upon the trials of Krupp’s new breech-loaders, and these trials, and those of Armstrong in this country, confirmed the formidable character of the new ordnance. Armour was also improving its power; compound armour (of combined steel and iron) was found to possess unexpected powers of resistance to penetration.
The torpedo, moreover, in its growing efficiency was now beginning to have an effect, not only on the details of ship design, but on the whole nature of naval warfare. The influence of the torpedo in its various forms had been appreciated in the early days of the decade.[171] The catastrophic but, happily, fictitious Battle of Dorking, fought in the pages of Blackwood’s Magazine in 1871, had been preceded by a naval action in which all but one of our fine ironclads had been sunk by torpedoes in attempting to ram the French fleet. The moral was obvious. From that time onwards the potential effect of the torpedo was seen to be very great. The ram seemed at last to have found a check. And it appeared that, in combating the ram, the torpedo had once more given the primacy to the fast-improving gun. Broadside actions of the old type, carried on at high range and speed, were predicted.[172]
In 1880 a new type of battleship was evolved of sufficient permanence to form the basis of whole classes of future ships.
An intimate account of the genesis of the Collingwood design is given us by the biographer of Sir Cooper Key, to illustrate the manner in which that prescient administrator succeeded in forecasting the trend of future construction. In ’66, he says, Captain Key had put on paper a résumé of his ideas on warship design which was clearly several years in advance of current opinion. Briefly, he had maintained that the specifications for our first-class battleships of the future should be drawn to cover the following features so far as possible:—moderate speed, small length and great handiness; perfect protection for vital parts and a complete water-line belt, rather than protection for personnel and above-water structure; a main-deck armament of broadside guns of medium calibre amidships, and of lighter calibre towards the ends, in combination with an upper-deck armament of four large guns in two unarmoured barbettes, one mounted before the foremast and one abaft the mizzen-mast; no sails. But for some years no approach was made to this ideal ship of Captain Key’s; the ideas it embodied were antagonistic to those held by the great majority of his brother officers.