Naval artillery
Naval artillery is artillery mounted on a warship, originally used only for naval warfare and then subsequently used for shore bombardment and anti-aircraft roles. The term generally refers to tube-launched projectile-firing weapons and excludes self-propelled projectiles such as torpedoes, rockets, and missiles and those simply dropped overboard such as depth charges and naval mines. Origins. The idea of ship-borne artillery dates back to the classical era. Julius Caesar indicates the use of ship-borne catapults against Britons ashore in his "Commentarii de Bello Gallico". The dromons of the Byzantine Empire carried catapults and  fire-throwers. From the late Middle Ages onwards, warships began to carry cannons of various calibres. The Mongol invasion of Java introduced cannons to be used in naval warfare (e.g. Cetbang by the Majapahit). The Battle of Arnemuiden, fought between England and France in 1338 at the start of the Hundred Years' War, was the first recorded European naval battle using artillery. The English ship "Christopher" was armed with three cannon and one hand gun. In Asia naval artillery are recorded from the Battle of Lake Poyang in 1363 and in considerable quantities at the Battle of Jinpo in 1380  with cannon made by Choe Museon. 80 Koryo warships successfully repelled 500 Japanese pirates referred to as Wokou using long range cannon fire. By the 15th century most Mediterranean powers were utilising heavy cannon mounted on the bow or stern of a vessel and designed to bombard fortresses on shore. By mid-century some vessels also carried smaller broadside cannon for bombarding other vessels immediately prior to an attempted boarding. These small guns were anti-personnel weapons and were fired at point blank range to accompany engagement with muskets or bows. From the 1470s both the Portuguese and Venetian navies  were experimenting with cannon as anti-ship weapons. King John II of Portugal, while still a prince in 1474, is credited with pioneering the introduction of a reinforced deck on the old Henry-era caravel to allow the mounting of heavy guns for this purpose. These were initially wrought iron breech-loading weapons known as basilisks, but by the early sixteenth century the navies of the Mediterranean had universally adopted lighter and more accurate muzzleloaders, cast in bronze and capable of firing balls or stones weighing up to . In 1489 John of Portugal further contributed to the development of naval  artillery by establishing the first standardized teams of trained naval gunners ("bombardeiros"). Age of Sail. Transition. The 16th century was an era of transition in naval warfare. Since ancient times, war at sea had been fought much like that on land: with melee weapons and bows and arrows, but on floating wooden platforms rather than battlefields. Though the introduction of guns was a significant change, it only slowly changed the dynamics of ship-to-ship combat. As guns became heavier and able to take more powerful gunpowder charges, they needed to be placed lower in the ship, closer to the  water line. Although some 16th-century galleys mounted broadside cannon, they did so at the expense of rowing positions which sacrificed speed and mobility. Most early cannon were still placed in the forecastle and aftercastle of a ship where they might be conveniently pointed in any direction. Early naval artillery was an antipersonnel weapon to deter boarders, because cannon powerful enough to damage ships were heavy enough to destabilize any ship mounting them in an elevated castle. Throughout the century, naval artillery was the single greatest advantage the Portuguese held over their rivals in the Indian Ocean, and the Portuguese  crown spared no expense in procuring and producing the best naval guns European technology permitted. Being a crown industry, cost considerations did not curb the pursuit of the best quality, best innovations and best training. The crown paid wage premiums and bonuses to lure the best European artisans and gunners to advance the industry in Portugal. Every cutting-edge innovation introduced elsewhere was immediately appropriated into Portuguese naval artillery – that includes bronze cannon (Flemish/German), breech-loading swivel-guns, truck carriages (possibly English), and the idea (originally French, c. 1501) of cutting square gunports ("portinhola" in Portuguese – also already created  and tested in the Portuguese ships since 1490) in the hull to allow heavy cannon to be mounted below deck. In this respect, the Portuguese spearheaded the evolution of modern naval warfare, moving away from the medieval warship, a carrier of armed men, aiming for the grapple, towards the modern idea of a floating artillery piece dedicated to resolving battles by gunnery alone. The anti-ship broadside. Gun ports cut in the hull of ships were introduced as early as 1501 in France, as early as 1496 in some Mediterranean navies, and in 1490 in Portugal, about a decade before  the famous Tudor era ship "Mary Rose" was launched in 1511. This made broadsides, coordinated volleys from all the guns on one side of a ship, possible for the first time in history, at least in theory. Ships such as "Mary Rose" carried a mixture of cannon of different types and sizes, many designed for land use, and using incompatible ammunition at different ranges and rates of fire. "Mary Rose", like other ships of the time, was built during a period of rapid development of heavy artillery, and her armament was a mix of old designs and innovations. The heavy  armament was a mix of older-type wrought iron and cast bronze guns, which differed considerably in size, range and design. The large iron guns were made up of staves or bars welded into cylinders and then reinforced by shrinking iron hoops and breech loaded, from the back, and equipped with simpler gun-carriages made from hollowed-out elm logs with only one pair of wheels, or without wheels entirely. The bronze guns were cast in one piece and rested on four-wheel carriages which were essentially the same as those used until the 19th century. The breech-loaders were  cheaper to produce and both easier and faster to reload, but could take less powerful charges than cast bronze guns. Generally, the bronze guns used cast iron shot and were more suited to penetrate hull sides while the iron guns used stone shot that would shatter on impact and leave large, jagged holes, but both could also fire a variety of ammunition intended to destroy rigging and light structure or injure enemy personnel. The majority of the guns were small iron guns with short range that could be aimed and fired by a single person. The two most common are  the "bases", breech-loading swivel guns, most likely placed in the castles, and "hailshot pieces", small muzzle-loaders with rectangular bores and fin-like protrusions that were used to support the guns against the railing and allow the ship structure to take the force of the recoil. Though the design is unknown, there were two "top pieces" in a 1546 inventory (finished after the sinking) which was probably similar to a base, but placed in one or more of the fighting tops. During rebuilding in 1536, "Mary Rose" had a second tier of carriage-mounted long guns fitted. Records show  how the configuration of guns changed as gun-making technology evolved and new classifications were invented. In 1514, the armament consisted mostly of anti-personnel guns like the larger breech-loading iron "murderers" and the small "serpentines", "demi-slings" and stone guns. Only a handful of guns in the first inventory were powerful enough to hole enemy ships, and most would have been supported by the ship's structure rather than resting on carriages. The inventories of both the "Mary Rose" and the Tower had changed radically by 1540. There were now the new cast bronze "cannons", "demi-cannons", "culverins  and sakers" and the wrought iron "port pieces" (a name that indicated they fired through ports), all of which required carriages, had longer range and were capable of doing serious damage to other ships. Various types of ammunition could be used for different purposes: plain spherical shot of stone or iron smashed hulls, spiked bar shot and shot linked with chains would tear sails or damage rigging, and canister shot packed with sharp flints produced a devastating shotgun effect. Trials made with replicas of culverins and port pieces showed that they could penetrate wood the same thickness of the "Mary  Rose's" hull planking, indicating a stand-off range of at least 90 m (295 ft). The port pieces proved particularly efficient at smashing large holes in wood when firing stone shot and were a devastating anti-personnel weapon when loaded with flakes or pebbles. A perrier threw a stone projectile three quarters of a mile (1.2 km), while cannon threw a 32-pound ball a full mile (1.6 km), and a culverin a 17-pound ball a mile and a quarter (2 km). Swivel guns and smaller cannon were often loaded with grapeshot for antipersonnel use at closer ranges , while the larger cannon might be loaded with a single heavy cannonball to cause structural damage. In Portugal, the development of the heavy galleon removed even the necessity of bringing carrack firepower to bear in most circumstances. One of them became famous in the conquest of Tunis in 1535, and could carry 366 bronze cannon (a possible exaggeration – or possibly not – of the various European chroniclers of the time, that reported this number; or also possibly counting the weapons in reserve). This ship had an exceptional capacity of fire for its time, illustrating the evolution that was operating at the  time, and for this reason, it became known as "Botafogo", meaning literally "fire maker", "torcher" or "spitfire" in popular Portuguese. Maturation. Naval artillery and tactics stayed relatively constant during the period 1571–1862, with large, sail-powered wooden naval warships mounting a great variety of different types and sizes of cannon as their main armament. By the 1650s, the line of battle had developed as a tactic that could take advantage of the broadside armament. This method became the heart of naval warfare during the Age of Sail, with navies adapting their strategies and tactics in order to get the most  broadside-on fire. Cannon were mounted on multiple decks to maximise broadside effectiveness. Numbers and calibre differed somewhat with preferred tactics. France and Spain attempted to immobilize ships by destroying rigging with long-range, accurate fire from their swifter and more maneuverable ships, while England and the Dutch Republic favoured rapid fire at close range to shatter a ship's hull and disable its crew. A typical broadside of a Royal Navy ship of the late 18th century could be fired 2–3 times in approximately 5 minutes, depending on the training of the crew, a well trained one being essential  to the simple yet detailed process of preparing to fire. French and Spanish crews typically took twice as long to fire an aimed broadside. An 18th-century ship of the line typically mounted 32-pounder or 36-pounder long guns on a lower deck, and 18- or 24-pounders on an upper deck, with some 12-pounders on the forecastle and quarterdeck. From the late sixteenth century it was routine for naval ships to carry a master gunner, responsible for overseeing the operation of the cannon on board. Originally a prestigious position, its status declined throughout the Age of Sail  as responsibility for gunnery strategy was devolved to midshipmen or lieutenants. By the eighteenth century the master gunner had become responsible only for the maintenance of the guns and their carriages, and for overseeing supplies of gunpowder and shot. In status the master gunner remained equal to the boatswain and ship's carpenter as senior warrant officers, and was entitled to the support of one or more gunner's mates. In the Royal Navy, the master gunner also directed the "quarter gunners" able seamen with the added responsibility of managing the rate and direction of fire from any set of  four gun crews. The British Admiralty did not see fit to provide additional powder to captains to train their crews, generally only allowing 1/3 of the powder loaded onto the ship to be fired in the first six months of a typical voyage, barring hostile action. Instead of live fire practice, most captains exercised their crews by "running" the guns in and out—performing all the steps associated with firing but for the actual discharge. Some wealthy captains—those who had made money capturing prizes or from wealthy families—were known to purchase powder with their own funds to enable  their crews to fire real discharges at real targets. Firing. Firing a naval cannon required a great amount of labour and manpower. The propellant was gunpowder, whose bulk had to be kept in a special storage area below deck for safety. "Powder boys", typically 10–14 years old, were enlisted to run powder from the armoury up to the gun decks of a vessel as required. A typical firing procedure follows. A wet swab was used to mop out the interior of the barrel, extinguishing any embers from a previous firing which might set off the next charge of gunpowder prematurely . Gunpowder, either loose or in a cloth or parchment cartridge pierced by a metal 'pricker' through the touch hole, was placed in the barrel and followed by a cloth wad (typically made from canvas and old rope), then rammed home with a rammer. Next the shot was rammed in, followed by another wad (to prevent the cannonball from rolling out of the barrel if the muzzle was depressed.) The gun in its carriage was then 'run out'—men heaved on the gun tackles until the front of the gun carriage was hard up against the ship's bulwark, and the barrel  protruding out of the gun port. This took the majority of the guncrew manpower as the total weight of a large cannon in its carriage could reach over two tons, and the ship would probably be rolling. The touch hole in the rear ('breech') of the cannon was primed with finer gunpowder ('priming powder'), or a 'quill' (from a porcupine or such, or the skin-end of a feather) pre-filled with priming powder, then ignited. The earlier method of firing a cannon was to apply a linstock—a wooden staff holding a length of smoldering match at the end —to the touch-hole of the gun. This was dangerous and made accurate shooting from a moving ship difficult, as the gun had to be fired from the side, to avoid its recoil, and there was a noticeable delay between the application of the linstock and the gun firing. In 1745, the British began using "gunlocks" (flintlock mechanisms fitted to cannon). The gunlock was operated by pulling a cord, or lanyard. The gun-captain could stand behind the gun, safely beyond its range of recoil, and sight along the barrel, firing when the roll of the ship lined the gun  up with the enemy and so avoid the chance of the shot hitting the sea or flying high over the enemy's deck. Despite their advantages, gunlocks spread gradually as they could not be retrofitted to older guns. The British adopted them faster than the French, who had still not generally adopted them by the time of the Battle of Trafalgar (1805), placing them at a disadvantage as they were in general use by the Royal Navy at this time. After the introduction of gunlocks, linstocks were retained, but only as a backup means of firing. The linstock slow match , or the spark from the flintlock, ignited the priming powder, which in turn set off the main charge, which propelled the shot out of the barrel. When the gun discharged, the recoil sent it backwards until it was stopped by the breech rope—a sturdy rope made fast to ring bolts set into the bulwarks, and a turn taken about the gun's cascabel, the knob at the end of the gun barrel. Artillery and shot. The types of artillery used varied from nation and time period. The more important types included the demi-cannon, the culverin and demi-culverin , and the carronade. One descriptive characteristic which was commonly used was to define guns by their 'pound' rating: theoretically, the weight of a single solid iron shot fired by that bore of cannon. Common sizes were 42-pounders, 36-pounders, 32-pounders, 24-pounders, 18-pounders, 12-pounders, 9-pounders, 8-pounders, 6-pounders, and various smaller calibres. French ships used standardized guns of 36-pound, 24-pound and 12-pound calibres, augmented by smaller pieces. In general, larger ships carrying more guns carried larger ones as well. The muzzle-loading design and weight of the iron placed design constraints  on the length and size of naval guns. Muzzle loading required the cannon muzzle to be positioned within the hull of the ship for loading. The hull is only so wide, with guns on both sides, and hatchways in the centre of the deck also limit the room available. Weight is always a great concern in ship design as it affects speed, stability, and buoyancy. The desire for longer guns for greater range and accuracy, and greater weight of shot for more destructive power, led to some interesting gun designs. One unique naval gun was the long nine. It was  a proportionately longer-barrelled 9-pounder. Its typical mounting as a bow or stern chaser, where it was not perpendicular to the keel, allowed room to operate this longer weapon. In a chase situation, the gun's greater range came into play. However, the desire to reduce weight in the ends of the ship and the relative fragility of the bow and stern portions of the hull limited this role to a 9-pounder, rather than one which used a 12 or 24 pound shot. In the reign of Queen Elizabeth advances in manufacturing technology allowed the English Navy Royal  to start using matched cannon firing standard ammunition, allowing firing of coordinated broadsides (although that was more of a matter of improved training and discipline than of matched guns). Different types of shot were employed for various situations. Standard fare was the round shot—spherical cast-iron shot used for smashing through the enemy's hull, holing his waterline, smashing gun carriages and breaking masts and yards, with a secondary effect of sending large wooden splinters flying about to maim and kill the enemy crew. At very close range, two round shots could be loaded in one gun and fired  together. "Double-shotting", as it was called, lowered the effective range and accuracy of the gun, but could be devastating within pistol shot range. Canister shot consisted of metallic canisters which broke open upon firing, each of which was filled with hundreds of lead musket balls for clearing decks like a giant shotgun blast; it is commonly mistakenly called "grapeshot", both today and in historic accounts (typically those of landsmen). Although canister shot could be used aboard ship, it was more traditionally an army artillery projectile for clearing fields of infantry. Grapeshot was similar in that it also consisted of  multiple (usually 9–12) projectiles that separated upon firing, except that the shot was larger (at least 1 inch in diameter, up to 3 inches or larger for heavier guns), and it either came in bundles held together by lengths of rope wrapped around the balls and wedged between, with wooden bases to act as wadding when rammed down the muzzles, or in canvas sacks wrapped about with rope. The name "grapeshot" comes from the former's apparent resemblance to a bunch of grapes. When fired, the inertial forces would cause the bundle to disintegrate, and the shot would spread out  to hit numerous targets. Grapeshot was a naval weapon, and existed for almost as long as naval artillery. The larger size of the grapeshot projectiles was desirable because it was more capable of cutting thick cordage and smashing equipment than the relatively smaller musket balls of a canister shot, although it could rarely penetrate a wooden hull. Although grapeshot won great popular fame as a weapon used against enemy crew on open decks (especially when massed in great numbers, such as for a boarding attempt), it was originally designed and carried primarily for cutting up enemy rigging. A more specialized  shot for similar use, chain-shot consisted of two iron balls joined together with a chain, and was particularly designed for cutting large swaths of rigging—anti-boarding netting and sails. It was far more effective than other projectiles in this use, but was of little use for any other purpose. "Bar shot" was similar, except that it used a solid bar to join the two balls; the bar could sometimes also extend upon firing. Series of long chain links were also used in a similar way. Bags of junk, such as scrap metal, bolts, rocks, gravel, or old musket  balls, were known as 'langrage', and were fired to injure enemy crews (although this was not common, and when it was used, it was generally aboard non-commissioned vessels such as privateers, actual pirate ships, merchantmen, and others who couldn't afford real ammunition). In China and other parts of Asia, fire arrows were thick, dartlike, rocket-propelled incendiary projectiles with barbed points, wrapped with pitch-soaked canvas which took fire when the rocket was launched, which could either be from special launching racks or from a cannon barrel (see "Chongtong", "Bō hiya".) The point stuck in sails, hulls or  spars and set fire to the enemy ship. In Western naval warfare, shore forts sometimes heated iron shot red-hot in a special furnace before loading it (with water-soaked wads to prevent it from setting off the powder charge prematurely.) The hot shot lodging in a ship's dry timbers would set the ship afire. Because of the danger of fire aboard (and the difficulty of heating and transporting the red-hot shot aboard ship), heated shot was seldom used from ship-mounted cannon, as the danger to the vessel deploying it was almost as great as to the  enemy; fire was the single greatest fear of all men sailing in wooden ships. Consequently, for men aboard these vessels, going up against shore artillery firing heated shot was a terrifying experience, and typically wooden fleets were not expected to brave such fire except in cases of great emergency, as a single heated shot could easily destroy the entire ship and crew, while the same ship could typically be expected to survive numerous hits from normal solid shot. In later years, the spherical exploding shell came into use. It first saw use in shore fortifications, and then relatively low-risk  applications such as bomb-ketches, which used mortars, which required an explosive shell to be effective. However, the long trajectory of a mortar meant that long fuses could be used, which reduced the risk of premature explosion, and such vessels were small and cheap in any case. It took some time for them to be adopted aboard other combat ships, largely due to the imprecise nature of the fuses then available; with the short fuse-lengths required at naval battle ranges, it was not uncommon for shells to explode inside the gun barrel, or shortly after leaving the muzzle, which  would pose a great risk to the vessel, and combat vessels represented a very large investment which a government could ill afford to lose. The risk of having to have such dangerous ammunition stocked above waterline during combat was also cited, as gunpowder in a rigid enclosure will explode with far more violence than if simply packed in a fabric sack, as propellant charges were. The strongly traditionalist nature of many senior naval officers was also a factor. Nevertheless, explosive shells were adopted for use aboard ship by the early 19th century. It had already been proven, from ships facing  bombardment from shell-armed shore batteries, that wooden ships were vulnerable to shell-fire, which both caused massive blast and wood- and metal-fragmentation damage (and hence very high crew casualties), but also scattered red-hot, jagged fragments all about, which embedded themselves into the wooden hull and acted much the same as heated shot, or simply ignited many of the flammable objects and materials lying about on a normal wooden ship, lighting oils, tar, tarred cords, powder charges, etc. The quick destruction wrought by explosive shells on vessels during the American Civil War brought quick recognition of this in  most cases. Although it is popularly believed that it was the advent of the ironclad vessel that single-handedly brought about the end of the wooden sailing ship, the recognition of their terrible vulnerability to explosive shells was equally vital in this transition, if not more so. Even without the factor of armored hulls to consider, the spectre of fleets of wooden ships decimating each other with shell-fire was unattractive to naval nations like Great Britain, which relied not only on maintaining a great fleet, but also on adding captured enemy vessels to it. The idea of a battle  that, even in victory, would likely cost them over half of their engaged vessels and probably leave few if any suitable candidates for capture was unappealing. Combined with the protection afforded by ironclad hulls, the destructive power of explosive shells on wooden vessels ensured their rapid replacement in the first-line combat duties with ironclad vessels. Bomb ketch. The bomb ketch was developed as a wooden sailing naval ship with its primary armament as mortars mounted forward near the bow and elevated to a high angle, and projecting their fire in a ballistic arc. Explosive shells or carcasses were employed  rather than solid shot. Bomb vessels were specialized ships designed for bombarding (hence the name) fixed positions on land. The first recorded deployment of bomb vessels by the English was for the Siege of Calais in 1347 when Edward III deployed single deck ships with Bombardes and other artillery. The first specialised bomb vessels were built towards the end of the 17th century, based on the designs of Bernard Renau d'Eliçagaray, and used by the French Navy. Five such vessels were used to shell Algiers in 1682 destroying the land forts, and killing some 700 defenders. Two years later the  French repeated their success at Genoa. The early French bomb vessels had two forward-pointing mortars fixed side-by-side on the foredeck. To aim these weapons, the entire ship was rotated by letting out or pulling in a spring anchor. The range was usually controlled by adjusting the gunpowder charge. The Royal Navy continued to refine the class over the next century or more, after Huguenot exiles brought designs over to England and the United Provinces. The side-by-side, forward-pointing mortars were replaced in the British designs by mortars mounted on the centerline on revolving platforms. These  platforms were supported by strong internal wooden framework to transmit the forces of firing the weapons to the hull. The interstices of the framework were used as storage areas for ammunition. Early bomb vessels were rigged as ketches with two masts. They were awkward vessels to handle, in part because bomb ketches typically had the masts stepped farther aft than would have been normal in other vessels of similar rig, in order to accommodate the mortars forward and provide a clear area for their forward fire. As a result, by the 1800s British bomb vessels were designed as full-rigged  ships with three masts, and two mortars, one between each neighboring pair of masts. Scientific gunnery. The art of gunnery was put on a scientific basis in the mid-18th century. British military engineer Benjamin Robins used Newtonian mechanics to calculate the projectile trajectory while taking the air resistance into account. He also carried out an extensive series of experiments in gunnery, embodying his results in his famous treatise on " New Principles in Gunnery" (1742), which contains a description of his ballistic pendulum (see chronograph). Robins also made a number of important experiments on the resistance of the air to the  motion of projectiles, and on the force of gunpowder, with computation of the velocities thereby communicated to projectiles. He compared the results of his theory with experimental determinations of the ranges of mortars and cannon, and gave practical maxims for the management of artillery. He also made observations on the flight of rockets, and wrote on the advantages of rifled gun barrels. Robins argued for the use of larger bore cannon and the importance of tightly fitting cannonballs. His work on gunnery was translated into German by Leonhard Euler and was heavily influential on the development of naval weaponry across  Europe. Another artillery scientist was George Marshall. Warrant Officer George Marshall was a Master Gunner in the United Navy. He wrote " Marshall's Practical Marine Gunnery" in 1822. Marshall was a naval artillery specialist. The book was the first scientific-technical book on naval artillery published in the United States for the U.S. Navy. He discussed cannons and fireworks. The book discusses the dimensions and apparatus necessary for the equipment of naval artillery. It features tables and charts. The book goes into further details regarding the distance of a shot on a ship based on the sound of the gun , which was found to fly at a rate of 1142 feet in one second. It was the standard of the time. According to Marshall's equation after seeing the flash of a cannon and hearing the blast the gunner would count the seconds until impact. This way a trained ear would know the distance a cannonball traveled based on ear training. The book example outlines a 9-second scenario where the distance the cannon was fired from the gunner was approximately 10,278 feet or 3,426 yards. Technical innovations. By the outbreak of the French Revolutionary Wars in 1793, a series  of technical innovations over the course of the late 18th century combined to give the British fleet a distinct superiority over the ships of the French and Spanish navies. The carronade was a short-barrelled gun which threw a heavy ball developed by the Carron Company, a Scottish ironworks, in 1778. Because of irregularities in the size of cannonballs and the difficulty of boring out gun barrels, there was usually a considerable gap between the ball and the bore—often as much as a quarter of an inch—with a consequent loss of efficiency. This gap was known as the  windage. The manufacturing practices introduced by the Carron Company reduced the windage considerably, enabling the ball to be fired with less powder and hence a smaller and lighter gun. The carronade was half the weight of an equivalent long gun, but could throw a heavy ball over a limited distance. The light weight of the carronade meant that the guns could be added to the forecastle and quarterdeck of frigates and ships of the line, increasing firepower without affecting the ship's sailing qualities. It became known as the "Smasher" and gave ships armed with carronades a great advantage at  short range. The mounting, attached to the side of the ship on a pivot, took the recoil on a slider. The reduced recoil did not alter the alignment of the gun. The smaller gunpowder charge reduced the guns' heating in action. The pamphlet advocated the use of woollen cartridges, which, although more expensive, eliminated the need for wadding and worming. Simplifying gunnery for comparatively untrained merchant seamen in both aim and reloading was part of the rationale for the gun. The replacement of trunnions by a bolt underneath, to connect the gun to the mounting, reduced the width of the  carriage enhancing the wide angle of fire. A carronade weighed a quarter as much and used a quarter to a third of the gunpowder charge for a long gun firing the same cannonball. Its invention is variously ascribed to Lieutenant General Robert Melville in 1759, or to Charles Gascoigne, manager of the Carron Company from 1769 to 1779. Carronades initially became popular on British merchant ships during the American Revolutionary War. A lightweight gun that needed only a small gun crew and was devastating at short range was a weapon well suited to defending merchant ships against French and American  privateers. In the Action of 4 September 1782, the impact of a single carronade broadside fired at close range by the frigate HMS "Rainbow" under Henry Trollope caused a wounded French captain to capitulate and surrender the "Hebe" after a short fight. Flintlock firing mechanisms for cannon were suggested by Captain Sir Charles Douglas and introduced during the American War of Independence in place of the traditional matches. Flintlocks enabled a higher rate of fire and greater accuracy as the gun captain could choose the exact moment of firing. Prior to this the Royal Navy introduced the use of goose  quills filled with powder during the Seven Years' War giving an almost instantaneous burn time compared with earlier methods of detonation. Douglas also innovated a system that greatly increased the field of fire. By the simple expedient of attaching the gun ropes at a greater distance from the gunports, the range through which each cannon could be traversed was greatly improved. The new system was first tested at the Battle of the Saintes in 1782, where the "Duke", "Formidable" and "Arrogant", and perhaps other British ships, had adopted Douglas's new system. The shrapnel shell was developed in 1784, by  Major General Henry Shrapnel of the Royal Artillery. Canister shot was already in widespread use at the time; a tin or canvas container filled with small iron or lead balls burst open when fired, giving the effect of an oversized shotgun shell. Shrapnel's innovation was to combine the multi-projectile shotgun effect of canister shot, with a time fuze to open the canister and disperse the bullets it contained at some distance along the canister's trajectory from the gun. His shell was a hollow cast-iron sphere filled with a mixture of balls and powder, with a crude  time fuze. If the fuze was set correctly then the shell would break open, either in front or above the intended target, releasing its contents (of musket balls). The shrapnel balls would carry on with the "remaining velocity" of the shell. In addition to a denser pattern of musket balls, the retained velocity could be higher as well, since the shrapnel shell as a whole would likely have a higher ballistic coefficient than the individual musket balls (see external ballistics). Industrial era and the Age of Steamships. The Industrial Revolution introduced steam-powered ironclad warships seemingly impervious to cast cannon . The inadequacy of naval artillery caused the naval ram to reappear as a means of sinking armored warships. The rapidity of innovation through the last half of the 19th century caused some ships to be obsolete before they were launched. Maximum projectile velocity obtainable with gunpowder in cast cannon was approximately . Increased projectile weight through increased caliber was the only method of improving armor penetration with this velocity limitation. Some ironclads carried extremely heavy, slow-firing guns of calibres up to . These guns were the only weapons capable of piercing the ever-thicker iron armour on the later ironclads, but  required steam powered machinery to assist loading cannonballs too heavy for men to lift. Explosive shells. Explosive shells had long been in use in ground warfare (in howitzers and mortars), but they were only fired at high angles and with relatively low velocities. Shells are inherently dangerous to handle, and no solution had been found to combine the explosive character of the shells with the high power and flatter trajectory of a high velocity gun. However, high trajectories were not practical for marine combat and naval combat essentially required flat-trajectory guns in order to have some decent odds of  hitting the target. Therefore, naval warfare had consisted for centuries of encounters between flat-trajectory cannon using inert cannonballs, which could inflict only local damage even on wooden hulls. The first naval gun designed to fire explosive shells was the Paixhans gun, developed by the French general Henri-Joseph Paixhans in 1822–1823. He advocated using flat-trajectory shell guns against warships in 1822 in his "Nouvelle force maritime et artillerie", and developed a delaying mechanism which, for the first time, allowed shells to be fired safely in high-powered flat-trajectory guns. The effect of explosive shells lodging into wooden  hulls and then detonating was potentially devastating. This was first demonstrated by Henri-Joseph Paixhans in trials against the two-decker "Pacificateur" in 1824, in which he successfully broke up the ship. Two prototype Paixhans guns had been cast in 1823 and 1824 for this test. Paixhans reported the results in "Experiences faites sur une arme nouvelle". The shells were equipped with a fuse which ignited automatically when the gun was fired. The shell would then lodge itself in the wooden hull of the target before exploding a moment later. The first Paixhans guns for the French Navy were manufactured  in 1841. The barrel of the guns weighed about 10,000 lbs. (4.5 metric tons), and proved accurate to about two miles. In the 1840s, Britain, Russia and the United States adopted the new naval guns. The effect of the guns in an operational context was decisively demonstrated during the Crimean War. The incendiary properties of exploding shells demonstrated the obsolescence of wooden warships in the 1853 Battle of Sinop; but detonation effectiveness was limited by use of gunpowder bursting charges. Early high explosives used in torpedo warheads would detonate during the acceleration of firing from a gun. After brief use  of dynamite guns aboard , picric acid became widely used in conventional naval artillery shells during the 1890s. Breech-loading, rifled artillery. William Armstrong was awarded a contract by the British government in the 1850s to design a revolutionary new piece of artillery—the Armstrong Gun—produced at the Elswick Ordnance Company. This marked the birth of modern artillery both on land and at sea. The piece was rifled, which allowed for a much more accurate and powerful action. The necessary machinery to accurately rifle artillery was only available by the mid-19th century. The cast iron shell of the Armstrong gun  was similar in shape to a Minié ball and had a thin lead coating which made it fractionally larger than the gun's bore and which engaged with the gun's rifling grooves to impart spin to the shell. This spin, together with the elimination of windage as a result of the tight fit, enabled the gun to achieve greater range and accuracy than existing smooth-bore muzzle-loaders with a smaller powder charge. His gun was also a breech-loader. Although attempts at breech-loading mechanisms had been made since medieval times, the essential engineering problem was that the  mechanism couldn't withstand the explosive charge. It was only with the advances in metallurgy and precision engineering capabilities during the Industrial Revolution that Armstrong was able to construct a viable solution. The gun combined all the properties that make up an effective artillery piece. The gun was mounted on a carriage in such a way as to return the gun to firing position after the recoil. What made the gun really revolutionary lay in the technique of the construction of the gun barrel that allowed it to withstand much more powerful explosive forces. The "built-up" method involved assembling  the barrel with wrought-iron (later mild steel was used) tubes of successively smaller diameter. The next tube would be heated to allow it to expand and fit over the previous tube. When it cooled the tube would contract to a slightly smaller diameter, which allowed an even pressure along the walls of the gun which was directed inward against the outward forces that the gun firing exerted on the barrel. Built-up guns with rifling made cast cannon obsolete by 1880. Armstrong's system was adopted in 1858, initially for "special service in the field" and initially he only  produced smaller artillery pieces, 6-pounder (2.5 in/64 mm) mountain or light field guns, 9-pounder (3 in/76 mm) guns for horse artillery, and 12-pounder (3 inches /76 mm) field guns. However, despite the gun's advantages, an 1863 Ordnance Select committee decided to revert to muzzle-loading artillery pieces on the grounds of cost and efficiency. Large-caliber breech-loading naval artillery became practical with French development of the interrupted screw obturator by Charles Ragon de Bange in 1872. It was only after a serious accident on board in 1879 when the left muzzleloading gun in the forward  turret exploded during practice firing in the Sea of Marmora killing 11 and injuring a further 35, that the Royal Navy decisively changed to breech loading guns. Improved loading and handling procedures were also adopted, and Thunderer herself was re-equipped with long-calibre 10" breech-loaders. Breech loading artillery overcame barrel length limitations of cast cannon imposed by the necessity of retracting the cannon into the hull for reloading through the muzzle. Simultaneous availability of longer barrels and slower burning brown powder increased projectile velocities to . Spin-stabilized elongated projectiles offered both reliable positioning of percussion fuzes and improved  armor penetration through increased sectional density. Gun turrets. Before the development of large-calibre, long-range guns in the mid-19th century, the classic battleship design used rows of port-mounted guns on each side of the ship, often mounted in casemates. Firepower was provided by a large number of guns which could only be aimed in a limited arc from one side of the ship. Due to instability, fewer larger and heavier guns can be carried on a ship. Also, the casemates often sat near the waterline, which made them vulnerable to flooding and restricted their use to calm seas . Turrets were weapon mounts designed to protect the crew and mechanism of the artillery piece and with the capability of being aimed and fired in many directions as a rotating weapon platform. This platform can be mounted on a fortified building or structure such as an anti-naval land battery, or on a combat vehicle, a naval ship, or a military aircraft. During the Crimean War, Captain Cowper Phipps Coles constructed a raft with guns protected by a 'cupola' and used the raft, named "Lady Nancy", to shell the Russian town of Taganrog in the Black Sea. "Lady Nancy" "proved  a great success", and Coles patented his rotating turret after the war. Following Coles' patenting, the British Admiralty ordered a prototype of Coles' design in 1859, which was installed in the floating battery vessel, , for trials in 1861, becoming the first warship to be fitted with a revolving gun turret. Coles' design aim was to create a ship with the greatest possible all round arc of fire, as low in the water as possible to minimise the target. The Admiralty accepted the principle of the turret gun as a useful innovation, and incorporated it into other new designs. Coles submitted  a design for a ship having ten domed turrets each housing two large guns. The design was rejected as impractical, although the Admiralty remained interested in turret ships and instructed its own designers to create better designs. Coles enlisted the support of Prince Albert, who wrote to the first Lord of the Admiralty, the Duke of Somerset, supporting the construction of a turret ship. In January 1862, the Admiralty agreed to construct a ship, , which had four turrets and a low freeboard, intended only for coastal defence. Coles was allowed to design the turrets, but the ship was the responsibility  of the chief Constructor Isaac Watts. Another of Coles' designs, , was completed in August 1864. Its existing broadside guns were replaced with four turrets on a flat deck and the ship was fitted with of armour in a belt around the waterline. Early ships like "Monitor" and "Royal Sovereign" had little sea-keeping qualities, being limited to coastal waters. Coles, in collaboration with Sir Edward James Reed, went on to design and build , the first seagoing warship to carry her guns in turrets. Laid down in 1866 and completed in June 1869, it carried two turrets, although the inclusion of  a forecastle and poop prevented the guns firing fore and aft. The gun turret was independently invented by the Swedish inventor John Ericsson in America, although his design was technologically inferior to Coles'. Ericsson designed in 1861. Its most prominent feature was a large cylindrical gun turret mounted amidships above the low-freeboard upper hull, also called the "raft". This extended well past the sides of the lower, more traditionally shaped hull. A small armored pilot house was fitted on the upper deck towards the bow, however, its position prevented "Monitor" from firing her guns straight forward. One of Ericsson 's prime goals in designing the ship was to present the smallest possible target to enemy gunfire. The turret's rounded shape helped to deflect cannon shot. A pair of donkey engines rotated the turret through a set of gears; a full rotation was made in 22.5 seconds during testing on 9 February 1862. Fine control of the turret proved to be difficult as the engine would have to be placed in reverse if the turret overshot its mark or another full rotation could be made. Including the guns, the turret weighed approximately ; the entire weight rested on an iron  spindle that had to be jacked up using a wedge before the turret could rotate. The spindle was in diameter, which gave it ten times the strength needed in preventing the turret from sliding sideways. When not in use, the turret rested on a brass ring on the deck that was intended to form a watertight seal. In service, however, this proved to leak heavily, despite caulking by the crew. The gap between the turret and the deck proved to be a problem as debris and shell fragments entered the gap and jammed the turrets of several s, which used  the same turret design, during the First Battle of Charleston Harbor in April 1863. Direct hits at the turret with heavy shot also had the potential to bend the spindle, which could also jam the turret. The turret was intended to mount a pair of smoothbore Dahlgren guns, but they were not ready in time and guns were substituted. Each gun weighed approximately . "Monitor"s guns used the standard propellant charge of specified by the 1860 ordnance for targets "distant", "near", and "ordinary", established by the gun's designer Dahlgren himself. They could fire a round shot or shell up to  a range of at an elevation of +15°. HMS "Thunderer" represented the culmination of this pioneering work. An ironclad turret ship designed by Edward James Reed, it was equipped with revolving turrets that used pioneering hydraulic turret machinery to maneouvre the guns. It was also the world's first mastless battleship, built with a central superstructure layout, and became the prototype for all subsequent warships. of 1871 was another pivotal design, and led directly to the modern battleship. Armour-piercing shot. The late 1850s saw the development of the ironclad warship, which carried wrought iron armor of considerable thickness . This armor was practically immune to both the round cast-iron cannonballs then in use and to the recently developed explosive shell. The first solution to this problem was effected by Major Sir W. Palliser. His Palliser shot, approved in 1867, was made of cast iron, the head being chilled in casting to harden it, using composite molds with a metal, water cooled portion for the head. At times there were defects that led to cracking in the projectiles but these were overcome with time. Bronze studs were installed into the outside of the projectile so as to engage the  rifling grooves in the gun barrel. The base had a hollow pocket but was not filled with powder or explosive: the cavity was necessitated by difficulties in casting large solid projectiles without their cracking when they cooled, because the nose and base of the projectiles cooled at different rates, and in fact a larger cavity facilitated a better quality casting. At the Battle of Angamos (8 October 1879) the Chilean ironclad warships fired twenty 250-pound-Palliser gunshots against the Peruvian monitor , with devastating results. It was the first time that such piercing shells were used in actual combat. These  chilled iron shots proved very effective against wrought iron armor, but were not serviceable against compound and steel armor, which was first introduced in the 1880s. A new departure therefore had to be made, and forged steel rounds with points hardened by water took the place of the Palliser shot. At first, these forged-steel rounds were made of ordinary carbon steel, but as armor improved in quality, the projectiles followed suit. During the 1890s and subsequently, cemented steel armor became commonplace, initially only on the thicker armor of warships. To combat this, the projectile was formed of steel—forged  or cast—containing both nickel and chromium. Another change was the introduction of a soft metal cap over the point of the shell – so called "Makarov tips" invented by Russian admiral Stepan Makarov. This "cap" increased penetration by cushioning some of the impact shock and preventing the armor-piercing point from being damaged before it struck the armor face, or the body of the shell from shattering. It could also help penetration from an oblique angle by keeping the point from deflecting away from the armor face. (See: APCBC ammunition) Increased armor penetration became possible when projectile velocities of were  obtained as smokeless powder propellants replaced gunpowder about 1900. Quick-firing artillery. Underwater hull damage possible with torpedoes encouraged development of small, inexpensive torpedo boats capable of sinking the largest warships. By the end of the 19th century, all warships required a defensive battery of quick-firing guns capable of hitting fast, maneuverable torpedo boats. The Royal Navy first introduced the quick-firing 4.7-inch gun in HMS "Sharpshooter" in 1889, and the quick-firing 6-inch MK 1 in , launched 1891. Other navies followed suit; the French Navy installed quick-firing weapons on its ships completed in 1894–95. Quick -firing guns were a key characteristic of the pre-dreadnought battleship, the dominant design of the 1890s. The quick-firing guns, while unable to penetrate thick armour, were intended to destroy the superstructure of an opposing battleship, start fires, and kill or distract the enemy's gun crews. The development of heavy guns and their increasing rate of fire meant that the quick-firer lost its status as the decisive weapon of naval combat in the early 1900s, though quick-firing guns were vital to defend battleships from attack by torpedo boats and destroyers, and formed the main armament of  smaller vessels. Most late-19th-century warships mounted naval artillery of more than one caliber because of uncertainty about the relative destruction possible from a few large shells (which might miss) in comparison to the increased hit probability of a larger number of less damaging small-caliber shells fired within the same time period. Quick-firing guns were initially breech-loading weapons firing ammunition small enough to be loaded by hand. Later substitution of brass cartridges for silk powder bags allowed increased rates of fire using sliding wedge breech blocks. Increasing mechanization ultimately enabled similar rates of fire from naval artillery  calibers up to . Fire control. When gunnery ranges increased dramatically in the late 19th century, it was no longer a simple matter of calculating the proper aim point, given the flight times of the shells. Increasingly sophisticated mechanical calculators were employed for proper gunlaying, typically with various spotters and distance measures being sent to a central plotting station deep within the ship. There the fire direction teams fed in the location, speed and direction of the ship and its target, as well as various adjustments for Coriolis effect, weather effects on the air, and other adjustments. The resulting directions, known  as a firing solution, would then be fed back out to the turrets for laying. If the rounds missed, an observer could work out how far they missed by and in which direction, and this information could be fed back into the computer along with any changes in the rest of the information and another shot attempted. The situation for naval fire control was highly complex, due to the need to control the firing of several guns at once. In naval engagements both the firing guns and target are moving, and the variables are compounded by the greater distances and  times involved. Rudimentary naval fire control systems were first developed around the time of World War I. Arthur Pollen and Frederic Charles Dreyer independently developed the first such systems. Pollen began working on the problem after noting the poor accuracy of naval artillery at a gunnery practice near Malta in 1900. Lord Kelvin, widely regarded as Britain's leading scientist, first proposed using an analogue computer to solve the equations which arise from the relative motion of the ships engaged in the battle and the time delay in the flight of the shell to calculate the required trajectory and therefore  the direction and elevation of the guns. Pollen aimed to produce a combined mechanical computer and automatic plot of ranges and rates for use in centralised fire control. To obtain accurate data of the target's position and relative motion, Pollen developed a plotting unit (or plotter) to capture this data. He added a gyroscope to allow for the yaw of the firing ship. Again this required substantial development of the, at the time, primitive gyroscope to provide continuous reliable correction. Trials were carried out in 1905 and 1906, which although completely unsuccessful showed promise. He was encouraged in his  efforts by the rapidly rising figure of Admiral Jackie Fisher, Admiral Arthur Knyvet Wilson and the Director of Naval Ordnance and Torpedoes (DNO), John Jellicoe. Pollen continued his work, with tests carried out on Royal Navy warships intermittently. Meanwhile, a group led by Dreyer designed a similar system. Although both systems were ordered for new and existing ships of the Royal Navy, the Dreyer system eventually found most favour with the Navy in its definitive Mark IV* form. The addition of director control facilitated a full, practicable fire control system for World War I ships, and most RN capital ships  were so fitted by mid 1916. The director was high up over the ship where operators had a superior view over any gunlayer in the turrets. It was also able to co-ordinate the fire of the turrets so that their combined fire worked together. This improved aiming and larger optical rangefinders improved the estimate of the enemy's position at the time of firing. The system was eventually replaced by the improved "Admiralty Fire Control Table" for ships built after 1927. Big-gun battleships. Significant gunnery developments occurred in the late 1890s and the early 1900s, culminating with the  launch of the revolutionary in 1906. Sir Percy Scott was given command of HMS "Scylla" in 1896, where he was able to implement his new theories on gunnery, scoring the unprecedented success of 80% during the 1897 gunnery trials. This was totally unprecedented, as the average in the Royal Navy was just 28%. Scott noted that night time signalling between ships in the fleet was slow and inaccurate. He addressed this in two ways: he devised training aids and put his signallers under instruction and he devised a new more effective flashing lamp. The new efficiency of his ship's  signalling was adopted by the whole Mediterranean fleet. He devised a new sub-calibre gun which involved fitting a one-inch-calibre rifled barrel inside the barrel of the main armament but which used the main gun's controls. He also came up with new sights employing telescope optics and new training targets. In the Navy's 1901 prize firing, "Terrible" achieved the same score of 80%, and Scott's gunnery practices were adopted by other ships in the fleet. Later, Scott taught at the naval gunnery school at Whale Island, Hampshire. a largely honorary role which he held until  promotion to flag rank in 1905. The development of the torpedo meant that it became necessary to engage an enemy at ranges outside torpedo range. This in turn meant that the old system whereby a gunlayer in each turret pointed and fired the turret guns independently could no longer be expected to achieve a significant hit rate on an opposing ship. Scott was instrumental in encouraging the development and installation of director firing, a system whereby the guns were all pointed, elevated and fired from a single point, usually at the top of the foremast. By firing all the guns  simultaneously it was possible to observe the simultaneous splashes produced and correct the aim visually. As battle ranges were pushed out to an unprecedented , the distance was great enough to force gunners to wait for the shells to arrive before applying corrections for the next salvo. A related problem was that the shell splashes from the more numerous smaller weapons tended to obscure the splashes from the bigger guns. Either the smaller-calibre guns would have to hold their fire to wait for the slower-firing heavies, losing the advantage of their faster rate of fire, or it would be  uncertain whether a splash was due to a heavy or a light gun, making ranging and aiming unreliable. Italian naval architect Vittorio Cuniberti first argued for the concept of an all-big-gun battleship in 1903, proposing an "ideal" future British battleship of , with a main battery of a dozen 12-inch guns in eight turrets, 12 inches of belt armour, and a speed of . First Sea Lord Sir John Fisher pushed through the Board of Admiralty a decision to arm the next battleship with 12-inch guns and that it would have a speed no less than . The result  was HMS "Dreadnought", which rendered all previous ships immediately obsolescent on its launch in 1906. The ship mounted the 45-calibre BL 12-inch Mark X gun in five twin gun turrets. These could deliver a broadside of a maximum of eight guns and could be elevated up to +13.5°. They fired projectiles at a muzzle velocity of ; at 13.5°, this provided a maximum range of with armour-piercing (AP) 2 crh shells. At 16° elevation, the range was extended to using the more aerodynamic, but slightly heavier 4 crh AP shells. The rate of fire of  these guns was one to two rounds per minute. The ships carried 80 rounds per gun. Within five years of the commissioning of "Dreadnought", a new generation of more powerful "super-dreadnoughts" was being built. The arrival of the super-dreadnought is commonly believed to have started with the British . What made them 'super' was the unprecedented 2,000-ton jump in displacement, the introduction of the heavier 13.5-inch (343 mm) gun, and the placement of all the main armament on the centerline. In the four years between "Dreadnought" and "Orion", displacement had increased by 25%, and weight of broadside  had doubled. In comparison to the rapid obsolescence of the preceding half-century, naval artillery changed comparatively little through World War I and World War II. Battleships remained similar to "Dreadnought", torpedo boats evolved into destroyers, and ships of intermediate size were called cruisers. All ship types became larger as the calibre of heavy guns increased (to a maximum of in the s), but the number of guns carried remained similar. Smaller ships used smaller-calibre weapons which were also used on battleships as the defensive secondary armament. High-angle artillery. Although naval artillery had been designed to perform within  the classical broadside tactics of the age of sail, World War I demonstrated the need for naval artillery mounts capable of greater elevation for defending against aircraft. High-velocity naval artillery intended to puncture side armor at close range was theoretically capable of hitting targets miles away with the aid of fire control directors; but the maximum elevation of guns mounted within restrictive armored casemates prevented reaching those ranges. Dual purpose guns were devised to protect ships against both torpedo boats and aircraft. The QF 4 inch Mk V naval gun was one of the first artillery pieces to be  adapted as an anti-aircraft gun and mounted on ships for defence. It was first used in 1914 as a secondary armament on s in a high-angle anti-aircraft role. Most naval artillery on ships built after World War I was capable of elevating to at least 45°, and some guns as large as were capable of elevating to 70° for potential use against aircraft. As destroyers began to assume ASW roles to include protection of the fleet from submarines, they were fitted with high-angle depth charge mortars (called Y-guns, K-guns or squid). Naval  bombardment. Battleships were used in support of amphibious operations since the late 19th century in the form of naval bombardment. Under international law such bombardments are regulated by the general law of war and the "Bombardment by Naval Forces in Time of War (Hague Convention IX)"; 18 October 1907. At the beginning of World War I its principal practitioner was the Royal Navy. During the War RN ships fired against targets at Gallipoli, the Salonika front and along the Belgian Coast. In the Aegean, the problems were not especially challenging, and enemy coastal defences (forts, shore-batteries etc.) were fairly  unsophisticated; but along the Belgian Coast the Germans constructed an extensive, well-equipped and well-coordinated system of gun-batteries to defend the coast. Ports, such as Ostend and Zeebrugge were of major importance to the U-boat campaign and were frequently bombarded by British monitors operating from Dover and Dunkirk. The Royal Navy continually advanced their technology and techniques necessary to conduct effective bombardments in the face of the German defenders—firstly refining aerial reconnaissance techniques, then experimenting with night-bombardment and moving on to adopt indirect fire. Finally, in the summer of 1918, monitors were equipped with Gyro  Director Training gear, which effectively provided the Director with a gyro-stabilised Artificial Line of Sight, and thereby enabled a ship to carry out Indirect Bombardment while underway. This was a very significant advance, and established a firm foundation for naval bombardment as practiced by the Royal Navy and United States Navy during World War II. The practice reached its zenith during World War II, when the availability of man-portable radio systems and sophisticated relay networks allowed forward observers to transmit targeting information and provide almost instant accuracy reports—once troops had landed. Battleships, cruisers and destroyers would pound  shore installations, sometimes for days, in the hope of reducing fortifications and attriting defending forces. Obsolete battleships unfit for combat against other ships were often used as floating gun platforms expressly for this purpose. However, given the relatively primitive nature of the fire control computers and radar of the era combined with the high velocity of naval gunfire, accuracy was poor until troops landed and were able to radio back reports to the ship. Naval gunfire could reach as far as inland, and was often used to supplement land-based artillery. The heavy-calibre guns of some eighteen battleships and  cruisers were used to stop German Panzer counterattack at Salerno. Naval gunfire was used extensively throughout Normandy, although initially the surprise nature of the landings themselves precluded a drawn-out bombardment which could have reduced the Atlantic Wall defences sufficiently, a process that fell to specialist armoured vehicles instead. Artillery ranges. The effective range of naval artillery evolved over the course of its history. Decline. Aircraft began to replace naval artillery as more effective weapons against ships during WWII, and after the war guided missiles were added. Naval artillery calibers greater than were not installed on new ships after WWII . Ships used the old large-caliber artillery only for naval gunfire support. USS "Missouri", the last active ship with a large-caliber gun, was decommissioned in 1996. Submarines shed their deck guns as a handicap in modern naval tactics. Destroyers and frigates often carry a single gun of 3 inch to 5.1 inch (76mm to 130mm) calibre as a backup to missile systems and capable of land fire support. Smaller guns like the 20 mm Phalanx CIWS system are used for short-range defence against targets which cannot be engaged by guided weapons systems. Modern naval artillery  is nevertheless still capable of impressive performances. For example, the Italian 5 inch Otobreda 127/54 Compact can fire 40 rounds a minute at a range of over , or up to when using rocket-boosted, terminal guided "Vulcano GLR" rounds. Smaller, multi-role vessels are also seeing a resurgence. The Ukrainian Gurza-M is an example, armed with 2 turrets built by Mykolayiv Mechanical Repair Plant. In the early 21st century the use of railguns mounted on ships is under study.