The Conte di Cavour–class battleships were a group of three dreadnoughts built for the Royal Italian Navy (Regia Marina) in the 1910s. The ships were completed during World War I. In December 1915, and January 1916, when the Serbian army was driven by the German forces under General von Mackensen toward the Albanian coast, 138,000 Serbian infantry and 11,000 refugees were ferried across the Adriatic and landed in Italy in 87 trips by the and other ships of the Italian Navy under the command of Admiral Conz. These ships also carried 13,000 cavalrymen and 10,000 horses of the Serbian army to Corfu in 13 crossings from the Albanian port of Vallons. was sunk by a magazine explosion in 1916 and sold for scrap in 1923. The two surviving ships, and , supported operations during the Corfu Incident in 1923. They were extensively reconstructed between 1933 and 1937 with more powerful guns, additional armor and considerably more speed than before.
Both ships participated in the Battle of Calabria in July 1940, when Giulio Cesare was lightly damaged. They were both present when British torpedo bombers attacked the fleet at Taranto in November 1940, and Conte di Cavour was torpedoed. She was grounded with most of her hull underwater and her repairs were not completed before the Italian surrender in September 1943. Conte di Cavour was scrapped in 1946. Giulio Cesare escorted several convoys, and participated in the Battle of Cape Spartivento in late 1940 and the First Battle of Sirte in late 1941. She was designated as a training ship in early 1942, and escaped to Malta after Italy surrendered. The ship was transferred to the Soviet Union in 1949 and renamed Novorossiysk. The Soviets also used her for training until she was sunk when a mine exploded in 1955. She was scrapped in 1957.
Design and description
The Conte di Cavour–class ships were designed by Rear Admiral Engineer Edoardo Masdea, Chief Constructor of the Regia Marina, and were ordered in response to French plans to build the s. They were intended to be superior to the Courbets and to remedy 's perceived flaws of weak protection and armament. As upgrading a warship's protection and armament on a similar displacement typically requires a loss in speed, the ships were not designed to reach the of their predecessor. They were still given a advantage over the standard of most foreign dreadnoughts.Giorgerini, pp. 268–270, 272 Foreign dreadnoughts were being designed with guns, but the Regia Marina was forced to use guns in the Conte di Cavours because Italy lacked the ability to build larger guns.Stille, p. 12 An additional gun, making a total of 13, was added to offset this deficiency.Giorgerini, p. 269
Taking advantage of the lengthy building times of these ships, other countries were able to build dreadnoughts that were superior in protection and armament,Giorgerini, p. 270 with the exception of the French. Construction was delayed by late deliveries of the 305-millimeter guns and armor plates as well as shortages of labor. The Italo-Turkish War of 1911–1912 diverted workers at the shipyards for repairs and maintenance of the ships participating in the war. The Italians imported the raw nickel steel for their armor from America and Britain and processed it into their equivalent of Krupp cemented armor, called Terni cemented, but there were problems with this process and suitable plates took longer to produce than planned.
Basic characteristics The ships of the Conte di Cavour class were long at the waterline, and overall. They had a beam of , and a draft of .Fraccaroli, p. 259 They displaced at normal load, and at deep load. The Conte di Cavour class was provided with a complete double bottom and their hulls were subdivided by 23 longitudinal and transverse bulkheads. The ships had two rudders, both on the centerline. They had a crew of 31 officers and 969 enlisted men.Giorgerini, pp. 270, 272
Propulsion The original machinery for all three ships consisted of three Parsons steam turbine sets, arranged in three engine rooms. The center engine room housed one set of turbines that drove the two inner propeller shafts. It was flanked by compartments on either side, each housing one turbine set which powered the outer shafts. Steam for the turbines was provided by 20 Blechynden water-tube boilers in Conte di Cavour and Leonardo da Vinci, eight of which burned oil and twelve of which burned both oil and coal. Giulio Cesare used a dozen each oil-fired and mixed-firing Babcock & Wilcox boilers. Designed to reach a maximum speed of , none of the ships reached this goal on their sea trials, despite generally exceeding the rated power of their turbines. They only achieved speeds ranging from using . The ships could store a maximum of of coal and of fuel oilGiorgerini, pp. 268, 272–273 that gave them a range of at , and at . Each ship was equipped with three turbo generators that provided a total of 150 kilowatts at 110 volts.Bargoni & Gay, p. 17
Armament As built, the ships' main armament comprised thirteen 46-caliber long 305-mm Model 1909 guns, designed and built by Armstrong Whitworth and Vickers,Friedman, p. 234 in five gun turrets. The turrets were all on the centerline, with a twin-gun turret superfiring over a triple-gun turret in fore and aft pairs, and a third triple turret amidships, designated 'A', 'B', 'Q', 'X', and 'Y' from bow to stern. This was only one fewer gun than the Brazilian Rio de Janeiro then under construction, the most heavily armed battleship in the world; Rio de Janeiros guns were mounted in seven twin-gun turrets.Hore, p. 175 The turrets had an elevation capability of −5° to +20 degrees and the ships could carry 100 rounds for each gun, although 70 was the normal load. Sources disagree regarding these guns' performance, but naval historian Giorgio Giorgerini claims that they fired armor-piercing (AP) projectiles at the rate of one round per minute and that they had a muzzle velocity of which gave a maximum range of .Giorgerini, pp. 268, 276 The turrets had hydraulic training and elevation, with an auxiliary electric system.Bargoni & Gay, p. 14
The secondary armament on the first two ships consisted of eighteen 50-caliber M1909 guns,Campbell, p. 336 also designed by Armstrong Whitworth and Vickers,Friedman, pp. 240–241 mounted in casemates on the sides of the hull. These guns could depress to −10 degrees and had a maximum elevation of +15 degrees; they had a rate of fire of six shots per minute. They could fire a high-explosive projectile with a muzzle velocity of to a maximum distance of . The ships carried a total of 3,600 rounds for them. For defense against torpedo boats, the ships carried fourteen British built 50-caliber guns; thirteen of these could be mounted on the turret tops, but they could be mounted in 30 different positions, including some on the forecastle and upper decks. These guns had the same range of elevation as the secondary guns, and their rate of fire was higher at 10 rounds per minute. They fired a AP projectile with a muzzle velocity of to a maximum distance of . The ships were also fitted with three submerged torpedo tubes, one on each broadside and the third in the stern.Giorgerini, pp. 268, 276–277
Armor
The Conte di Cavour-class ships had a complete waterline armor belt that was high; of this was below the waterline and above. It had a maximum thickness of amidships, reducing to towards the stern and towards the bow. The lower edge of this belt was a uniform in thickness. Above the main belt was a strake of armor thick that extended up to the lower edge of the main deck. Above this strake was a thinner one, 130 millimeters thick, that extended from the bow to 'X' turret. The upper strake of armor protected the casemates and was thick. The ships had two armored decks: the main deck was thick in two layers on the flat that increased to on the slopes that connected it to the main belt. The second deck was thick, also in two layers. Fore and aft transverse bulkheads connected the armored belt to the decks.Giorgerini, pp. 270–271
The frontal armor of the gun turrets was in thickness with thick sides, and an roof and rear. Their barbettes also had 230-millimeter armor above the forecastleMcLaughlin, p. 421 deck that reduced to between the forecastle and upper decks and 130 millimeters below the upper deck. The forward conning tower had walls 280 mm thick; those of the aft conning tower were 180 millimeters thick.Giorgerini, pp. 270–272 The total weight of the protective armor was , just over 25 per cent of the ships' designed displacement. The total weight of the entire protective system was , 30.2 per cent of their intended displacement.Giorgerini, p. 272
Modifications and reconstruction
Shortly after the end of World War I, the number of 50-caliber 76 mm guns was reduced to 13, all mounted on the turret tops, and six new 40-caliber 76-mm Model 1916 anti-aircraft (AA) guns were installed abreast the aft funnel. In addition two license-built QF 2-pounder (40 mm) AA guns were mounted on the forecastle deck abreast 'B' turret. In 1925–1926 the foremast was replaced by a tetrapodal mast, which was moved forward of the funnels,Giorgerini, p. 277 the rangefinders were upgraded, and the ships were equipped to handle a Macchi M.18 seaplane mounted on the center turret. Around that same time, one or both of the ships was equipped with a fixed aircraft catapult on the port side of the forecastle.
The sisters began an extensive reconstruction program directed by Vice Admiral (Generale del Genio navale) Francesco Rotundi in October 1933. This lasted until June 1937 for Conte di Cavour and October 1937 for Giulio Cesare, and resulted in several changes. A new bow section was grafted over the existing bow which increased their length by to and their beam increased to . Their draft at deep load increased to for Conte di Cavour and for Giulio Cesare. All of the changes made during their reconstruction increased their displacement to at standard load and at deep load. The ships' crews increased to 1,260 officers and enlisted men.Brescia, p. 58 Only 40% of the original ship's structure remained after the reconstruction was completed.Bargoni & Gay, p. 19 Two of the propeller shafts were removed and the existing turbines were replaced by two Belluzzo geared steam turbines rated at . The boilers were replaced by eight superheated Yarrow boilers with a working pressure of . On her sea trials in December 1936, before her reconstruction was fully completed, Giulio Cesare reached a speed of from .McLaughlin, p. 422 In service their maximum speed was about . The ships now carried of fuel oil which provided them with a range of at a speed of .Bagnasco & Grossman, pp. 64–65
The center turret and the torpedo tubes were removed and all of the existing secondary armament and AA guns were replaced by a dozen 120-mm OTO 1933 guns in six twin-gun turrets and eight AA guns in twin turrets. In addition the ships were fitted with a dozen Breda 54-caliber light AA guns in six twin-gun mounts and twelve Breda M31 anti-aircraft machine guns, also in twin mounts.Bagnasco & Grossman, p. 65 The guns were bored out to and their turrets were modified to use electric power, a fixed loading angle of +12 degrees, and the guns could now elevate to +27 degrees.McLaughlin, p. 420 The 320 mm AP shells weighed and had a maximum range of with a muzzle velocity of .Campbell, p. 322 In 1940 the 13.2 mm machine guns were replaced by 65-caliber Breda Model 35 AA guns in twin mounts. Giulio Cesare received two more twin mounts as well as four additional 37 mm guns in twin mounts on the forecastle between the two turrets in 1941. The tetrapodal mast was replaced with a new forward conning tower, protected with thick armor.Bargoni & Gay, p. 21 Atop the conning tower there was a director fitted with two rangefinders, with a base length of .