The Andrea Doria class (usually called Duilio class in Italian sources) was a pair of dreadnought battleships built for the Royal Italian Navy (Regia Marina) between 1912 and 1916. The two ships—Andrea Doria and Duilio—were completed during World War I. The class was an incremental improvement over the preceding . Like the earlier ships, Andrea Doria and Duilio were armed with a main battery of thirteen guns.
The two ships were based in southern Italy during World War I to help ensure that the Austro-Hungarian Navy's surface fleet would be contained in the Adriatic. Neither vessel saw any combat during the conflict. After the war, they cruised the Mediterranean and were involved in several international incidents, including at Corfu in 1923. In 1933, both ships were placed in reserve. In 1937 the ships began a lengthy reconstruction. The modifications included removing their center main battery turret and boring out the rest of the guns to , strengthening their armor protection, installing new boilers and steam turbines, and lengthening their hulls. The reconstruction work lasted until 1940, by which time Italy was already engaged in World War II.
The two ships were moored in Taranto on the night of 11/12 November 1940 when the British launched a carrier strike on the Italian fleet. In the resulting Battle of Taranto, Duilio was hit by a torpedo and forced to beach to avoid sinking. Andrea Doria was undamaged in the raid; repairs for Duilio lasted until May 1941. Both ships escorted convoys to North Africa in late 1941, including Operation M42, where Andrea Doria saw action at the inconclusive First Battle of Sirte on 17 December. Fuel shortages curtailed further activities in 1942 and 1943, and both ships were interned at Malta following Italy's surrender in September 1943. Italy was permitted to retain both battleships after the war, and they alternated as fleet flagship until the early 1950s, when they were removed from active service. Both ships were scrapped after 1956.
Design and description
The Andrea Doria-class ships were designed by naval architect Vice Admiral (Generale del Genio navale) Giuseppe Valsecchi and were ordered in response to French plans to build the s. The design of the preceding s was generally satisfactory and was adopted with some minor changes. These mostly concerned the reduction of the superstructure by shortening the forecastle deck, the consequent lowering of the amidships gun turret and the upgrading of the secondary armament to sixteen guns in lieu of the eighteen guns of the older ships.Giorgerini, p. 278
General characteristics The ships of the Andrea Doria class were long at the waterline, and overall. They had a beam of , and a draft of . They displaced at normal load, and at deep load.Fraccaroli, p. 260 They were 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 ships were fitted with 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 powering the outer shafts. Steam for the turbines was provided by 20 Yarrow boilers, 8 of which burned oil and 12 of which burned coal sprayed with oil. Designed to reach a maximum speed of from , neither of the ships reached this goal on their sea trials, only achieving speeds of . The ships could store a maximum of of coal and of fuel oil that gave them a range of at .Giorgerini, pp. 272–73, 278
Armament As built, the ships' main armament comprised thirteen 46-caliber 305-millimeter guns,Preston, p. 179 designed 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 front to rear. The turrets had an elevation capability of −5 to +20 degrees and the ships could carry 88 rounds for each gun. Sources disagree regarding these guns' performance, but naval historian Giorgio Giorgerini says 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, 278
The secondary armament on the two ships consisted of sixteen 45-caliber guns, also designed by Armstrong Whitworth,Friedman, p. 240 mounted in casemates on the sides of the hull underneath the main guns. Their positions tended to be wet in heavy seas, especially the rear guns. These guns could depress to −5 degrees and had a maximum elevation of +20 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 3,440 rounds for them. For defense against torpedo boats, the ships carried nineteen 50-caliber guns; they could be mounted in 39 different positions, including on the turret roofs 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, 277–78
Armor The Andrea Doria-class ships had a complete waterline armor belt with a maximum thickness of that reduced to towards the stern and towards the bow.Whitley, p. 162 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 protected the casemates. 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 belt to the decks.Giorgerini, p. 271
The frontal protection of the gun turrets was in thickness with thick sides, and an roof and rear. Their barbettes had armor above the deck that reduced to between the forecastle and upper decks and 130 millimeters below the upper deck. The forward conning tower had walls thick; those of the aft conning tower were thick.
Modifications and reconstruction
During World War I, a pair of 50-caliber 76-millimeter guns on high-angle mounts were fitted as anti-aircraft (AA) guns, one gun at the bow and the other on top of 'X' turret. In 1925 the number of low-angle 50-caliber 76-millimeter guns was reduced to 13, all mounted on the turret tops, and six new 40-caliber 76-millimeter guns were installed abreast the aft funnel. Two license-built 2-pounder AA guns were also fitted. In 1926 the rangefinders were upgraded and a fixed aircraft catapult was mounted on the port side of the forecastle for a Macchi M.18 seaplane.Whitley, p. 164
By the early 1930s, the Regia Marina had begun design work on the new s, but it recognized that they would not be complete for some time. As a stop-gap measure in response to the new French s, the navy decided to modernize its old battleships; work on the two surviving Conte di Cavours began in 1933 and the two Andrea Dorias followed in 1937.Garzke & Dulin, p. 379 The work lasted until July 1940 for Duilio and October 1940 for Andrea Doria. The existing bow was dismantled and a new, longer, bow section was built, which increased their overall length by to (on the Cavour-class the new bow had been grafted over the existing one, instead). Their beam increased to Whitley, pp. 162, 164 and their draft at deep load increased to .Brescia, p. 62 The changes made during their reconstruction increased their displacement to for Andrea Doria and for Duilio at deep load. The ships' crews increased to 70 officers and 1,450 enlisted men.
Two of the propeller shafts were removed and the existing turbines were replaced by two sets of Belluzzo geared steam turbines rated at . The boilers were replaced by eight superheated Yarrow boilers. On their sea trials the ships reached a speed of , although their maximum speed was about in service. The ships now carried of fuel oil, which provided them with a range of at a speed of .
The center turret and the torpedo tubes were removed and all of the existing secondary armament and AA guns were replaced by a dozen guns in four triple-gun turrets and ten AA guns in single turrets. In addition the ships were fitted with fifteen 54-caliber Breda light AA guns in six twin-gun and three single mounts and sixteen Breda Model 35 AA guns, also in twin mounts. The 305-millimeter guns were bored out to 320 millimeters (12.6 in) and their turrets were modified to use electric power. They had a fixed loading angle of +12 degrees, but there is uncertainty on their new maximum elevation, with some sources citing a maximum value of +27 degrees,Whitley, pp. 158, 164–65 while others claim one of +30 degrees.Campbell, p. 324 The 320-millimeter AP shells weighed and had a maximum range of with a muzzle velocity of .Campbell, p. 322 In early 1942 the rearmost 20-millimeter mounts were replaced by twin 37-millimeter gun mounts and the 20-millimeter guns were moved to the roof of Turret 'B', while the RPC motors from the stabilized mounts of the 90 mm guns were removed.Whitley, p. 165Campbell, p. 343 The forward superstructure was rebuilt with a new forward conning tower, protected with thick armor. Atop the conning tower there was a fire-control director fitted with three large rangefinders.
The deck armor was increased during reconstruction to a total of . The armor protecting the secondary turrets was thick. The existing underwater protection was replaced by the Pugliese system that consisted of a large cylinder surrounded by fuel oil or water that was intended to absorb the blast of a torpedo warhead.Whitley, p. 158
These modernizations have been criticized by some naval historians because these ships would eventually prove to be inferior to the British battleships they were meant to face (namely the , since by the time the decision to proceed was taken a war between Italy and the United Kingdom seemed more likely). In addition, the cost of the reconstruction would be not much less than the cost of building a brand new Littorio-class battleship; moreover, the reconstruction work caused bottlenecks in the providing of steel plates, that caused substantial delays in the construction of the modern battleships, which otherwise might have been completed at an earlier date.
Ships + Construction data Ship Namesake Builder Laid downPreston, p. 179 Launched Completed Fate Admiral Andrea DoriaSilverstone, p. 294 Arsenale di La Spezia, La Spezia 24 March 1912 30 March 1913 13 March 1916 Scrapped, 1961 Gaius DuiliusSilverstone, p. 297 Regio Cantiere di Castellammare di Stabia, Castellammare di Stabia 24 February 1912 24 April 1913 10 May 1915 Scrapped, 1957Silverstone, p. 296
Service history