Learning Lincoln On-line
FROM-- SET FIVE, CIVIL WAR STUDIES
The turning point of the Civil War Naval War
Armament and Tactics
The adoption of iron armor meant that the traditional naval armament of dozens of light cannon became useless, since their shot would bounce off an armored hull. To penetrate armor, increasingly heavy guns were mounted on ships; nevertheless, the view that ramming was the only way to sink an ironclad became widespread. The increasing size and weight of guns also meant a movement away from the ships mounting many guns broadside, in the manner of a ship-of-the-line, towards a handful of guns in turrets for all-round fire.
Rams Used Again
From the 1860s to the 1880s many naval designers believed that the development of the ironclad meant that the ram was again the most important weapon in naval warfare. With steam power freeing ships from the wind, and armor making them invulnerable to shellfire, the ram seemed to offer the opportunity to strike a decisive blow.
The scant damage inflicted by the guns of Monitor and Virginia at Battle of Hampton Roads and the spectacular but lucky success of the Austrian flagship SMS Erzherzog Ferdinand Max sinking the Italian Re d'Italia at Lissa gave strength to the ramming craze. From the early 1870s to early 1880s most British naval officers thought that guns were about to be replaced as the main naval armament by the ram. Those who noted the tiny number of ships that had actually been sunk by ramming struggled to be heard.
The revival of ramming had a significant effect on naval tactics. Since the 17th century the predominant tactic of naval warfare had been the line of battle, where a fleet formed a long line to give it the best fire from its broadside guns. This tactic was totally unsuited to ramming, and the ram threw fleet tactics into disarray. The question of how an ironclad fleet should deploy in battle to make best use of the ram was never tested in battle, and if it had been, combat might have shown that rams could only be used against ships which were already stopped dead in the water.
The ram finally fell out of favor in the 1880s, as the same effect could be achieved with a torpedo, with less vulnerability to quick-firing guns.
The armament of ironclads tended to become concentrated in a small number of powerful guns capable of penetrating the armor of enemy ships at range; calibre and weight of guns increased markedly to achieve greater penetration. Throughout the ironclad era navies also grappled with the complexities of rifled versus smoothbore guns and breech-loading versus muzzle-loading.
HMS Warrior carried a mixture of 110-pounder 7 inch breech-loading rifles and more traditional 68-pounder smoothbore guns. Warrior highlighted the challenges of picking the right armament; the breech-loaders she carried, designed by Sir William Armstrong, were intended to be the next generation of heavy armament for the Royal Navy, but were shortly withdrawn from service.
Breech-loading guns seemed to offer important advantages. A breech-loader could be reloaded without moving the gun, a lengthy process particularly if the gun then needed to be re-aimed. The Warrior's Armstrong guns also had the virtue of being lighter than an equivalent smoothbore and, because of their rifling, more accurate. Nonetheless, the design was rejected because of problems which plagued breech-loaders for decades.
The weakness of the breech-loader was the obvious problem of sealing the breech. All guns are powered by the explosive conversion of gunpowder into gas. This explosion propels the shot or shell out of the front of the gun, but also imposes great stresses on the gun-barrel. If the breech — which experiences some of the greatest forces in the gun — is not entirely secure, then there is a risk that either gas will discharge through the breech or that the breech will break. This in turn reduces the muzzle velocity of the weapon and can also endanger the gun crew. The Warrior's Armstrong guns suffered from both problems; the shells were unable to penetrate the 4.5 in armor of Gloire, while sometimes the screw which closed the breech flew backwards out of the gun on firing. Similar problems were experienced with the breech-loading guns which became standard in the French and German navies.
These problems influenced the British to equip ships with muzzle-loading weapons of increasing power until the 1880s. After a brief introduction of 100-pounder or 9.5-inch smoothbore Somerset Gun, which weighed 6.5 tons, the Admiralty introduced 7-inch (178 mm) rifled guns, weighing 7 tons. These were followed by a series of increasingly mammoth weapons—guns weighing 12, 25, 25, 38 and finally 81 tons, with calibre increasing from 8-inch to 16-inch .
The decision to retain muzzle-loaders until the 1880s has been criticized by historians. However, at least until the late 1870s, the British muzzle-loaders had superior performance in terms of both range and rate of fire than the French and Prussian breech-loaders, which suffered from the same problems as had the first Armstrong guns.
Reloading the muzzle-loading guns of Caio Duilio
From 1875 onwards, the balance between breech- and muzzle-loading changed. Captain de Bange invented a method of reliably sealing a breech, adopted by the French in 1873. Just as compellingly, the growing size of naval guns made muzzle-loading much more complicated. With guns of such size there was no prospect of hauling in the gun for re-loading, or even re-loading by hand, and complicated hydraulic systems were required for re-loading the gun outside the turret without exposing the crew to enemy fire. In 1882, the 81-ton, 16-inch (406 mm) guns of HMS Inflexible fired only once every 11 minutes while bombarding Alexandria during the Urabi Revolt. The 100-ton, 450 mm (17.72 inch) guns of Caio Duilio could each fire a round every 15 minutes.
In the Royal Navy, the switch to breech-loaders was finally made in 1879; as well as the significant advantages in terms of performance, opinion was swayed by an explosion on board HMS Thunderer caused by a gun being double-loaded, a problem which could only happen with a muzzle-loading gun.
The calibre and weight of guns could only increase so far. The larger the gun, the slower it would be to load, the greater the stresses on the ship's hull, and the less the stability of the ship. The size of the gun peaked in the 1880s, with some of the heaviest calibres of gun ever used at sea. HMS Benbow carried two 16.25-inch (413 mm) breech-loading guns, each weighing 110 tons—no British battleship would ever carry guns as large. The Italian 450 mm (17.72 inch) guns would be larger than any gun fitted to a battleship until the 18.1-inch (460 mm) armament of the Japanese Yamato class of World War II. One consideration which became more acute was that even from the original Armstrong models, following the Crimean War, range and hitting power far exceeded simple accuracy, especially at sea where the slightest roll or pitch of the vessel as 'floating weapons-platform' could negate the advantage of rifling. American ordnance experts accordingly preferred smoothbore monsters whose round shot could at least 'skip' along the surface of the water. Actual effective combat ranges, they had learned during the Civil War, were comparable to those in the Age of Sail—though a vessel could now be smashed to pieces in only a few rounds. Smoke and the general chaos of battle only added to the problem. As a result, many naval engagements in the 'Age of the Ironclad' were still fought at ranges within easy eyesight of their targets, and well below the maximum reach of their ships' guns.
Another method of increasing firepower was to vary the projectile fired or the nature of the propellant. Early ironclads used black powder, which expanded rapidly after combustion; this meant cannons had relatively short barrels, to prevent the barrel itself slowing the shell. The sharpness of the black powder explosion also meant that guns were subjected to extreme stress. One important step was to press the powder into pellets, allowing a slower, more controlled explosion and a longer barrel. A further step forward was the introduction of chemically different brown powder which combusted more slowly again. It also put less stress on the insides of the barrel, allowing guns to last longer and to be manufactured to tighter tolerances.
The development of smokeless powder, based on nitroglycerine or nitrocellulose, by the French inventor Paul Vielle in 1884 was a further step allowing smaller charges of propellant with longer barrels. The guns of the pre-Dreadnought battleships of the 1890s tended to be smaller in calibre compared to the ships of the 1880s, most often 12 in (305 mm), but progressively grew in length of barrel, making use of improved propellants to gain greater muzzle velocity. The nature of the projectiles also changed during the ironclad period. Initially, the best armor-piercing projectile was a solid cast-iron shot. Later, shot of chilled iron, a harder iron alloy, gave better armor-piercing qualities. Eventually the armor-piercing shell was developed.
Positioning of Armament Broadside Ironclads
The first British, French and Russian ironclads, in a logical development of warship design from the long preceding era of wooden ships of the line, carried their weapons in a single line along their sides and so were called "broadside ironclads." Both Gloire and HMS Warrior were examples of this type. Because their armor was so heavy, they could only carry a single row of guns along the main deck on each side rather than a row on each deck.
A significant number of broadside ironclads were built in the 1860s, principally in Britain and France, but in smaller numbers by other powers including Italy, Austria, Russia and the United States. The advantages of mounting guns on both broadsides was that the ship could engage more than one adversary at a time, and the rigging did not impede the field of fire.
Broadside armament also had disadvantages, which became more serious as ironclad technology developed. Heavier guns to penetrate ever-thicker armor meant that fewer guns could be carried. Furthermore, the adoption of ramming as an important tactic meant the need for ahead and all-round fire. These problems led to broadside designs being superseded by designs that gave greater all-round fire, which included central-battery, turret, and barbette designs.
Turrets, Batteries and Barbettes
Barbette of the French ironclad Vauban (1882-1905)
There were two main design alternatives to the broadside. In one design, the guns were placed in an armoured casemate amidships: this arrangement was called the 'box-battery' or 'centre-battery'. In the other, the guns could be placed on a rotating platform to give them a broad field of fire; when fully armored, this arrangement was called a turret and when partially armored or unarmored, a barbette.
The centre-battery was the simpler and, during the 1860s and 1870s, the more popular method. Concentrating guns amidships meant the ship could be shorter and handier than a broadside type. The first full-scale centre-battery ship was HMS Bellerophon of 1865; the French laid down centre-battery ironclads in 1865 which were not completed until 1870. Centre-battery ships often, but not always, had a recessed freeboard enabling some of their guns to fire directly ahead.
The turret made its debut with USS Monitor in 1862, with a type of turret designed by the Swedish engineer John Ericsson. A competing turret design was proposed by the British inventor Cowper Coles. Ericsson's turret turned on a central spindle, and Coles's turned on a ring of bearings. Turrets offered the maximum arc of fire from the guns, but there were significant problems with their use in the 1860s. The fire arc of a turret would be considerably limited by masts and rigging, so they were unsuited to use on the earlier ocean-going ironclads. The second problem was that turrets were extremely heavy. Ericsson was able to offer the heaviest possible turret (guns and armour protection) by deliberately designing a ship with very low freeboard. The weight thus saved from having a high broadside above the waterline was diverted to actual guns and armour. Low freeboard, however, also meant a smaller hull and therefore a smaller capacity for coal storage—and therefore range of the vessel. In many respects, the turreted, low-freeboard Monitor and the broadside sailer HMS Warrior represented two opposite extremes in what an 'Ironclad' was all about. The most dramatic attempt to compromise these two extremes, or 'squaring this circle', was designed by Captain Cowper Phipps Coles: HMS Captain, a dangerously low freeboard turret ship which nevertheless carried a full rig of sail, and which subsequently capsized not long after her launch in 1870. Her half-sister HMS Monarch was restricted to firing from her turrets only on the port and starboard beams. The third Royal Navy ship to combine turrets and masts was HMS Inflexible of 1876, which carried two turrets on either side of the centre-line, allowing both to fire fore, aft and broadside.
A lighter alternative to the turret, particularly popular with the French navy, was the barbette. These were fixed armored towers which held a gun on a turntable. The crew was sheltered from direct fire, but vulnerable to plunging fire, for instance from shore emplacements. The barbette was lighter than the turret, needing less machinery and no roof armor—though nevertheless some barbettes were stripped of their armor plate to reduce the top-weight of their ships. The barbette became widely adopted in the 1880s, and with the addition of an armored 'gun-house', transformed into the turrets of the pre-Dreadnought battleships.
The ironclad age saw the development of explosive torpedoes as naval weapons, which helped complicate the design and tactics of ironclad fleets. The first torpedoes were static mines, used extensively in the American Civil War. That conflict also saw the development of the spar torpedo, an explosive charge pushed against the hull of a warship by a small boat. For the first time, a large warship faced a serious threat from a smaller one—and given the relative inefficiency of shellfire against ironclads, the threat from the spar torpedo was taken seriously. The U.S. Navy converted four of its monitors to become turretless armored spar-torpedo vessels while under construction in 1864–5, but these vessels never saw action. Another proposal, the towed or 'Harvey' torpedo, involved an explosive on a line or outrigger; either to deter a ship from ramming or to make a torpedo attack by a boat less suicidal.
A more practical and influential weapon was the self-propelled or Whitehead torpedo. Invented in 1868 and deployed in the 1870s, the Whitehead torpedo formed part of the armament of ironclads of the 1880s like HMS Inflexible and the Italian Caio Duilio and Enrico Dandolo. The ironclad's vulnerability to the torpedo was a key part of the critique of armored warships made by the Jeune Ecole school of naval thought; it appeared that any ship armored enough to prevent destruction by gunfire would be slow enough to be easily caught by torpedo. In practice, however, the Jeune Ecole was only briefly influential and the torpedo formed part of the confusing mixture of weapons possessed by ironclads.
Armor and Construction
The French Redoutable (1876), the first battleship to use steel as the main building material
The first ironclads were built on wooden or iron hulls, and protected by wrought iron armor backed by thick wooden planking. Ironclads were still being built with wooden hulls into the 1870s.
Hulls: iron, Wood and Steel
Using iron construction for warships offered advantages for the engineering of the hull. However, unarmored iron had many military disadvantages, and offered technical problems which kept wooden hulls in use for many years, particularly for long-range cruising warships.
Iron ships had first been proposed for military use in the 1820s. In the 1830s and 1840s, France, Britain and the United States had all experimented with iron-hulled but unarmored gunboats and frigates. However, the iron-hulled frigate was abandoned by the end of the 1840s, because iron hulls were more vulnerable to solid shot; iron was more brittle than wood, and iron frames more likely to fall out of shape than wood.
The unsuitability of unarmored iron for warship hulls meant that iron was only adopted as a building material for battleships when protected by armor. However, iron gave the naval architect many advantages. Iron allowed larger ships and more flexible design, for instance the use of watertight bulkheads on the lower decks. Warrior, built of iron, was longer and faster than the wooden-hulled Gloire. Iron could be produced to order and used immediately, in contrast to the need to give wood a long period of seasoning. And, given the large quantities of wood required to build a steam warship and the falling cost of iron, iron hulls were increasingly cost-effective. The main reason for the French use of wooden hulls for the ironclad fleet built in the 1860s was that the French iron industry could not supply enough, and the main reason why Britain built its handful of wooden-hulled ironclads was to make best use of hulls already started and wood already bought.
Wooden hulls continued to be used for long-range and smaller ironclads, because iron nevertheless had a significant disadvantage. Iron hulls suffered quick fouling by marine life, slowing the ships down—manageable for a European battle fleet close to dry docks, but a difficulty for long-range ships. The only solution was to sheath the iron hull first in wood and then in copper, a laborious and expensive process which made wooden construction remain attractive. Iron and wood were to some extent interchangeable: the Japanese Kongō and Hiei ordered in 1875 were sister-ships, but one was built of iron and the other of composite construction.
After 1872, steel started to be introduced as a material for construction. Compared to iron, steel allows for greater structural strength for a lower weight. The French Navy led the way with the use of steel in its fleet, starting with the Redoutable, laid down in 1873 and launched in 1876. Redoutable nonetheless had wrought iron armor plate, and part of her exterior hull was iron rather than steel.
Even though Britain led the world in steel production, the Royal Navy was slow to adopt steel warships. The Bessemer process for steel manufacture produced too many imperfections for large-scale use on ships. French manufacturers used the Siemens-Martin process to produce adequate steel, but British technology lagged behind. The first all-steel warships built by the Royal Navy were the dispatch vessels Iris and Mercury, laid down in 1875 and 1876.
Armor and Protection Schemes
The iron-and-wood armor of Warrior
Iron-built ships used wood as part of their protection scheme. HMS Warrior was protected by 4.5 in (114 mm) of wrought iron backed by 15 in (381 mm) of teak, the strongest shipbuilding wood. The wood played two roles, preventing spalling and also preventing the shock of a hit damaging the structure of the ship. Later, wood and iron were combined in 'sandwich' armor, for instance in HMS Inflexible.
Steel was also an obvious material for armor. It was tested in the 1860s, but the steel of the time was too brittle and disintegrated when struck by shells. Steel became practical to use when a way was found to fuse steel onto wrought iron plates, giving a form of compound armor. This compound armor was used by the British in ships built from the late 1870s, first for turret armor (starting with HMS Inflexible) and then for all armor (starting with HMS Colossus of 1882). The French and German navies adopted the innovation almost immediately, with licenses being given for the use of the 'Wilson System' of producing fused armor.
The first ironclads to have all-steel armor were the Italian Caio Duilio and Enrico Dandolo. Though the ships were laid down in 1873 their armor was not purchased from France until 1877. The French navy decided in 1880 to adopt compound armor for its fleet, but found it limited in supply, so from 1884 the French navy was using steel armor. Britain stuck to compound armor until 1889.
The ultimate ironclad armor was case hardened nickel-steel. In 1890, the U.S. Navy tested steel armor hardened by the Harvey process and found it superior to compound armor. For several years 'Harvey steel' was the state of the art, produced in the U.S., France, Germany, Britain, Austria and Italy. In 1894, the German firm Krupp developed gas cementing, which further hardened steel armor. The German Kaiser Friedrich III, laid down in 1895, was the first ship to benefit from the new 'Krupp armor' and the new armor was quickly adopted; the Royal Navy using it from HMS Canopus, laid down in 1896. By 1901 almost all new battleships used Krupp armor, though the U.S. continued to use Harvey armor alongside until the end of the decade.
The equivalent strengths of the different armor plates was as follows: 15 in (381 mm) of wrought iron was equivalent to 12 in (305 mm) of either plain steel or compound iron and steel armor, and to 7.75 in (197 mm) of Harvey armor or 5.75 in (146 mm) of Krupp armor.
Ironclad construction also prefigured the later debate in battleship design between tapering and 'all-or-nothing' armour design. Warrior was only semi-armoured, and could have been disabled by hits on the bow and stern. As the thickness of armor grew to protect ships from the increasingly heavy guns, the area of the ship which could be fully protected diminished. Inflexible's armor protection was largely limited to the central citadel amidships, protecting boilers and engines, turrets and magazines, and little else. An ingenious arrangement of cork-filled compartments and watertight bulkheads was intended to keep her stable and afloat in the event of heavy damage to her un-armored sections.
Information from Wikepedia. Complete article at http://en.wikipedia.org/wiki/Ironclad_warship