Andrea Doria - class battleship The " Andrea Doria " class was a pair of dreadnought battleship s built for the Royal Italian Navy ( " Regia Marina " ) during the early 1910s . Completed during World War I , neither ship saw any combat during the war . They were modernized during 1937 – 1940 , between the wars , and both participated in World War II , at the First Battle of Sirte , and on convoy duty . Design . The " Andrea Doria " - class ships were designed by Vice Admiral ( " Generale del Genio navale " ) Guiseppe 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 . 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 . 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 . 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 which powered the outer shafts . Steam for the turbines was provided by 20 Yarrow boilers , eight of which burned oil and twelve of which burned both oil and coal . 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 . Armament . As built , the ships ' main armament comprised thirteen 46 - caliber 305 - millimeter guns , designed by Armstrong Whitworth and Vickers , 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 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 . The secondary armament on the first two ships consisted of sixteen 45 - caliber guns , also designed by Armstrong Whitworth , mounted in casemate s on the sides of the hull underneath the main guns . Their positions tended to be a bit 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 a total of 3 , 440 rounds for them . For defense against torpedo boat s , 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 tube s , one on each broadside and the third in the stern . Armor . The " Andrea Doria " - class ships had a complete waterline armor belt that had a maximum thickness of , reducing to towards the stern and towards the bow . 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 armored belt to the decks . The frontal armor of the gun turrets was in thickness with thick sides , and an roof and rear . Their barbette s 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 gun s . In 1925 the number of 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 . In addition two license - built 2 - pounder anti - aircraft ( AA ) guns were also fitted . In 1926 the rangefinder s were upgraded and a fixed aircraft catapult was mounted on the port side of the forecastle for a Macchi M . 18 seaplane . The sisters began an extensive reconstruction program in 1937 that 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 . Their beam increased to and their draft at deep load increased to . All of 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 turbine rated at . The boilers were replaced by eight superheated Yarrow boilers . On their sea trials the ships reached a speeds 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 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 . The 320 - millimeter AP shells weighed and had a maximum range of with a muzzle velocity of . In early 1942 the rearmost 20 - millimeter guns mounts were replaced by twin 37 - millimeter gun mounts and the 20 - millimeter guns were moved to the roof of Turret ' B ' . 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 . Service history . Both ships were assigned to the 2nd Division at Taranto after their completion and they saw no combat during the war . They were transferred to the 1st Division in 1918 and " Andrea Doria " served as the division ' s flagship that year . " Andrea Doria " served at the First Battle of Sirte and as a convoy escort until interned after the armistice in September 1943 . She served as the Italian flagship in the 1950s . " Caio Duilio " was damaged at the Battle of Taranto by British aircraft . Because of fuel shortages , she was out of the war following the armistice . She was later a training ship and flagship of the Italian Navy until scrapped .