The conversion of the cast-iron guns was seen to be only a temporary expedient. Just as the smooth-bore cannon, after a last effort to overcome iron plates with spherical solid shot of the largest calibre, withdrew from the competition; so, as the thickness of armour increased, the converted cast-iron cannon, with its special armour-piercing shot of chilled iron, soon reached the limit of its power and gave place to the rifled artillery of wrought iron or steel.
And now, rifled ordnance having definitely supplanted the smooth-bore, a new struggle arose between the various systems of gunmaking, and more especially between the two rival methods of loading: by the breech and by the muzzle. The prognostications of those who had doubted whether the latter method was suitable for large ordnance were seen to be partially justified. Other nations had already relapsed into muzzle-loading, impressed by the complexity and weakness of the breech-loading systems of Cavalli, Wahrendorf and other inventors. Besides ourselves only the Prussians, the originators of the breech-loading rifled musket in its modern form, continued to trust in breech-loading ordnance. The Italians, following the example of the French and Americans, abandoned the system. “Thus,” said an English authority in ’62, “while, after more than four centuries of trial, other nations were giving up the moveable breech, ... we are still going from plan to plan in the hope of effecting what will, even if successful in closing the breech, be scarcely safe with the heavy charges necessary for smashing armour plates.”[129]
In the following year, ’63, the committee appointed to carry out the competitive trials between Whitworth and Armstrong guns, reported that the many-grooved system of rifling, with its lead-coated projectiles and complicated breech-loading arrangements, entailing the use of tin caps for obturation and lubricators for the rifling grooves, was far inferior for the general purposes of war to both of the muzzle-loading systems tried. This view received early and practical confirmation from a report sent to the Admiralty by Vice-Admiral Sir Augustus Kuper, after the bombardment of Kagosima. In that action several accidents occurred owing to the Armstrong guns being fired with their breech-blocks not properly screwed up. The guns were accordingly withdrawn from service and replaced by muzzle-loaders. In 1864 England reverted definitely to muzzle-loading ordnance, which, in the face of violent controversy and in spite of the gradual reconversion of her rivals to the breech-loading principle, she maintained for the next fifteen years. Whitworth’s system was adopted in the main, but the hexagonal form of bore and projectile was avoided. Studded projectiles were approved, the pieces being rifled with a few broad shallow grooves not unlike those used by the French. England at last possessed a muzzle-loading sea ordnance, characterized by ease and rapidity of loading, accuracy, cheapness, and capacity for firing, in emergency, spherical shot as well as rifled projectiles.
What was the effect of this retrogression upon the status of our naval armaments?
It seems frequently to have been held that, in view of the eventual victory of the breech-loading gun, the policy of reverting to muzzle-loading was wrong, and that this country was thereby placed at a serious disadvantage to her rivals. Several good reasons existed, however, for the preference given to muzzle-loading ordnance at that time. The accidents with removable breeches had been numerous and demoralizing. Muzzle-loading guns, besides the advantages which they possessed of strength, solidity and simplicity of construction, offered important advantages in ease and rapidity of loading—particularly in the case of turret or barbette guns, where “outside loading” was a great convenience. On the other hand the principal deficiency of the muzzle-loader, namely, the large windage required with studded projectiles, was now eliminated by the invention of the cupped “gas check,” a copper disc attached to the rear of the projectile which, on discharge, expanded automatically and sealed the bore.
Expert opinion confirmed the wisdom of the government policy. Experience, in the Franco-Prussian war and elsewhere, confirmed the views of the experts. “Reviewing the action of the artillerists who decided to adopt muzzle-loaders, with the greater experience we now possess it seems that they were right in their decision at the time it was first made; but there was too much hesitation in coming back to breech-loaders when new discoveries and great progress in powder quite altered conditions.”[130] In fact, once having abandoned the disparaged system, the country was with difficulty persuaded by the professionals to retrace its steps. In the end, ordnance followed small arms; the researches of Captain Noble at Elswick proved conclusively to the world at large the necessity for a reversion to breech-loading; and in 1880 the muzzle-loading gun was finally superseded by a greatly improved form of breech-loader.
In 1880 the state of knowledge and the conditions under which ordnance was manufactured were certainly altered from those of ’64. The struggle between guns and armour begun with the Gloire and Warrior had continued. In the presence of the new powers of mechanical science, artillerists and shipbuilders had sought to plumb the possibilities of offensive and defensive elements in warship design. Guns influenced armour, armour reacted on guns; both revolutionized contemporary naval architecture. It was in the effort to aggrandize the power of guns that Noble discovered that, with the existing powders and with the short muzzle-loading gun, a natural limit of power was soon reached. Better results could only be obtained, he showed, by the adoption of slow-burning powder and a longer gun; by the avoidance of the sudden high chamber pressure which resulted from the small-grained powder, and the substitution for it of a chamber pressure which would rise gradually to a safe maximum and then suffer only a gradual reduction as the gases expanded behind the moving projectile. The work done by the gases on the projectile could by this means be enormously increased. But, for this result, larger powder-charges were required; and these larger charges of slow-burning powder were found to require much larger chambers than those embodied in existing guns; in short, the new conditions called for a new shape of gun. Long guns, having powder chambers of larger diameter than that of the bore, were necessary, and these could not conveniently be made muzzle-loading.
So a return to the breech-loading ordnance became inevitable, and the change was made. The old Armstrong moveable vent-piece was avoided, however, in the new designs; of the two alternative breech-closing systems in use, viz. the wedge system of Krupp and the “interrupted screw” system of the French, the latter was adopted. A steel tube, rifled on the polygroove system, formed the body of the piece, and this was strengthened by hoops of iron or steel shrunk on its exterior. The new gun yielded a very great increase of power. Muzzle-loading guns were at once displaced, in the projected programme of new battleships, for the new type of ordnance, and a further series of revolutionary changes in ship armament at once took place. Other nations had already augmented the length and power of their guns. By the adoption of the improved breech-loading ordnance, Great Britain, who for the last few years had been falling behind her rivals, not only drew level with them but definitely took the lead in the power of her heavy ordnance: a lead which from that time to this she has successfully maintained.