The class was a class of two ironclad battleships built for the Italian (Royal Navy) in the 1870s and 1880s. The two ships— and —were designed by Benedetto Brin, who chose to discard traditional belt armor entirely, relying on a combination of very high speed and extensive internal subdivision to protect the ships. This, along with their armament of very large guns, has led some naval historians to refer to the class as prototypical battlecruisers.
Despite serving for over thirty years, the ships had uneventful careers. They spent their first two decades in service with the Active and Reserve Squadrons, where they were primarily occupied with training maneuvers. was converted into a training ship in 1902 and was significantly modernized in 1905–1908 before also becoming a training ship. They briefly saw action during the Italo-Turkish War, where they provided gunfire support to Italian troops defending Tripoli. was discarded in early 1915, though continued on as a guard ship during World War I, eventually being converted into a grain transport. She was ultimately broken up for scrap in 1921.
Design
Starting in the 1870s, following the Italian fleet's defeat at the Battle of Lissa, the Italians began a large naval expansion program, at first aimed at countering the Austro-Hungarian Navy. The s were the second class of the program, which also included the , designed in the early-1870s by Insp Eng Benedetto Brin. The class was ordered by Admiral Simone Antonio Saint-Bon, the Italian naval minister, who envisioned an improved version of the class that also had the ability to carry large numbers of soldiers, as the Navy had been given the responsibility of defending Italy's lengthy coastline.
Brin prepared the initial design in 1875. The need to keep the size of the ships under control, coupled with developments in armor-piercing shell technology, forced him to make significant alterations compared to the design to incorporate Saint Bon's requirements. It had come to be realized by naval designers in Italy and abroad that armor plate could no longer effectively resist the latest shell designs, so Brin reasoned that the great weight of an armor belt was unwarranted. Armor plate also tended to fragment when struck by shells, creating damage beyond that caused by the projectile itself, further militating against its use. Additionally, fitting belt armor on a ship the size of would cause a prohibitive increase in displacement, and so he discarded it completely in favor of a thin armored deck, unlike foreign capital ship designs.
Brin originally planned for the ships to displace , to have a main battery of two guns in individual barbettes, a secondary armament of eighteen guns, and to carry of coal for increased range over that of the class. Brin opted to use open barbettes over the heavy, enclosed gun turrets of the s to save weight, which permitted the addition of a full upper deck. This, in turn, provided the space to carry a division of 10,000 soldiers according to Saint Bon's requirements.
As the design evolved, developments in related technologies prompted changes to Brin's design. The development of slow-burning propellants led General Rosset, an artillerist in the Italian Army, suggested that slightly smaller, guns could be built with longer barrels for the same weight as the 450 mm guns. The longer barrels could take advantage of the slow-burning propellant to increase muzzle velocity, giving the guns better penetrating power. After the original guns were bought by Britain during a war scare with the Russian Empire in 1878, Brin altered the design to incorporate Rosset's ideas. The single 450 mm guns were replaced with pairs of 432 mm guns. By that time, he had made other changes, including reducing the 149 mm armament to eight weapons, and the coal capacity to , on displacement. The number of 149 mm guns was reduced because it was found that the additional guns could not have been manned when the 432 mm guns were in use.
The ships were authorized in 1875, with funding allocated to begin construction the following year, though design work continued even after they had been laid down in 1876. They were faster and more seaworthy than the preceding class, owing to their higher freeboard. They were very large and fast warships for their time, displacing over 15,000 tons at full load; could make , while could achieve . Other ironclads of the era could not make more than . Their high speed, powerful main battery, and thin armor protection has led to some naval historians to characterize the ships as proto-battlecruisers. Designed at a time when the primary threat to capital ships was a slow-firing gun equipped with cast iron shot, the s had the poor luck to enter service after quick-firing guns with explosive shells had been developed, rendering their protection scheme useless.
General characteristics
The ships of the class were long between perpendiculars and long overall. had a beam of , while was slightly narrower, at . The ships had a draft of and , respectively. displaced normally and up to at full load, while displaced normally and fully laden. The ships' great size allowed the designers to use very fine hull lines, which gave them high hydrodynamic efficiency and contributed to their speed.
Both ships' hulls had a ram bow and were constructed of steel, which offered a significant weight savings of 15 percent compared to iron hulls. Below the waterline, s hull was sheathed in wood and zinc to prevent biofouling, but was not similarly fitted. They had a double bottom that extended for , a distance that spanned the propulsion machinery rooms and the ammunition magazines. The hulls were divided into sixty-nine watertight compartments below the armor deck and another eighty-four in the double bottom. Steering was controlled by a single rudder, which was steam operated aboard and hydraulically driven aboard .
The -class vessels had a minimal superstructure. Both were fitted with a single military mast with fighting tops placed directly amidships; a small hurricane deck connected the ships' funnels and the mast. The deck was placed highly enough to allow the main battery guns to fully traverse, even with their barrels at maximum elevation. Atop the deck, a small bridge was placed. had a crew of 37 officers and 719 enlisted men, while had the same number of officers and 656 enlisted men. The ships had of freeboard. They each carried a number of small boats, including two second-class torpedo boats aboard and three picket boats aboard .
Propulsion machinery Their propulsion system consisted of four compound steam engines each driving a single screw propeller, which were in diameter. The engines could be run either in compound mode for greater fuel efficiency or in direct-acting mode for higher speed. Steam was supplied by twenty-six coal-fired, oval fire-tube boilers aboard , while received eight of the oval boilers and sixteen locomotive boilers. The ships' engine rooms were placed amidships, each engine in its own watertight compartment, with three boiler rooms on either end the engines. s boilers were trunked into six funnels, placed in two sets of three all on the centerline. only had four funnels in two pairs; during s refit in 1905–1908, her funnels were reduced to an identical arrangement.
The ships' propulsion system was projected to produce using forced draft to reach the intended top speed of . On her initial speed trials, s engines produced a top speed of from a maximum of , and she could maintain this speed for about an hour. was faster, with a top speed of from . The ships had a coal storage capacity of , though in practice likely carried . Figures for the ships' cruising radius vary; Conway's All the World's Fighting Ships reports that they could steam for at a speed of , while the historian Sergie Vinogradov states that they had a range of at the same speed.
Armament
and each carried a main armament of four breech-loading guns. received three 26-caliber guns and one 27-caliber gun, while was equipped entirely with 27-caliber guns. The former guns were the A model, and they fired a shell at a muzzle velocity of around , significantly better than the older 432 mm guns' for the same weight shell. The longer 27-caliber weapons produced an even higher velocity of ; armor penetration at the muzzle was and of wrought iron, respectively. Both caliber guns' rate of fire was very slow, taking eight minutes to reload after each shot, though they were still faster than the muzzle-loading 432 mm guns.
The guns were mounted in pairs en echelon amidships in a single, large, diagonal, oval barbette, with one pair of guns on a turntable to port and the other to starboard. The port pair was mounted aft of the starboard pair. The magazine was below the armored deck, and ammunition was brought up to the main guns via an armored trunk. They had to be returned to a fixed loading position after every shot: the forward guns pointed 45 degrees off the bow while the aft guns were 45 degrees from the stern. Records of ammunition storage vary; contemporary British sources report that carried forty-five shells per gun and was fitted with forty, while a Russian source reports fifty shells per gun for both vessels. The ships' high freeboard allowed the main guns to be mounted above the waterline, and the design and location of the barbette and turntables gave the guns good fields of fire. Their elevation ranged from −10 degrees to +15, which allowed them to engage targets as close as .
The ships carried a secondary battery of eight medium caliber guns in single pivot mounts. carried the originally-intended 149 mm 26.7-caliber guns, while received newer 32-caliber guns. These guns were distributed along the length of the ships; one was on the upper deck forward as a bow-chaser, four were on the broadside forward of the main battery, another pair were astern of the main guns, and the eighth gun was on the upper deck as a stern-chaser. These were supported by a battery of four guns, also in single mounts. The ships also carried a pair of mountain guns and two machine guns for use by landing parties ashore. As was customary for capital ships of the period, they carried four torpedo tubes. These were placed on the broadside above the waterline. The torpedoes carried a warhead and had a range of .
Armor
Instead of belt armor the ships were protected by a mild steel armored deck, the details of which are unclear. Vinogradov notes that contemporary sources report a range of thicknesses from 3 to 4.7 in. He suggests that the most likely explanation is that the ships were not identical. British intelligence reports credit with a deck thickness of in the central portion of the ship and reduced to 3 in at the bow and stern. The same reports state that had a uniform 3 in deck. The armored deck sloped downward to meet the ships' sides at a point below the waterline and combined with two bulkheads that ran the entire length of the ships, set back several feet from the side, and numerous other bulkheads interspersed among the two main bulkheads to create a hull extensively divided into watertight compartments. The resulting "cellular raft" of small compartments was designed to detonate shells before they could penetrate very far into the ships; confining the resulting explosion and flooding to limited areas, dampening and containing the effect.