Italian battleship Caio Duilio Caio Duilio was an Italian that served in the Regia Marina during World War I and World War II . She was named after the Roman fleet commander Gaius Duilius . " Caio Duilio " was laid down in February 1912 , launched in April 1913 , and completed in May 1916 . She was initially armed with a main battery of thirteen guns , but a major reconstruction in the late 1930s replaced these with ten guns . " Caio Duilio " saw no action during World War I owing to the inactivity of the Austro - Hungarian fleet during the conflict . She cruised the Mediterranean in the 1920s and was involved in the Corfu incident in 1923 . During World War II , she participated in numerous patrols and sorties into the Mediterranean , both to escort Italian convoys to North Africa and in attempts to catch the British Mediterranean Fleet . In November 1940 , the British launched an air raid on Taranto ; " Caio Duilio " was hit by one torpedo launched by a Fairey Swordfish torpedo bomber , which caused significant damage . Repairs lasted some five months , after which the ship returned to convoy escort duties . A fuel shortage immobilized the bulk of the Italian surface fleet in 1942 , and " Caio Duilio " remained out of service until the Italian surrender in September 1943 . She was thereafter interned at Malta until 1944 , when the Allies permitted her return to Italian waters . She survived the war , and continued to serve in the post - war Italian navy , primarily as a training ship . " Caio Duilio " was placed in reserve for a final time in 1953 ; she remained in the Italian navy ' s inventory for another three years before she was stricken from the naval register in late 1956 and sold for scrapping the following year . Design . " Caio Duilio " was long overall and had a beam of and a draft of . At full combat load , she displaced up to . She had a crew of 35 officers and 1 , 198 enlisted men . She was powered by four Parsons steam turbines , with steam provided by eight oil - fired and twelve coal and oil burning Yarrow boilers . The boilers were trunked into two large funnels . The engines were rated at , which provided a top speed of . She had a cruising radius of at . The ship was armed with a main battery of thirteen 46 - caliber guns in three triple turrets and two twin turrets . The secondary battery comprised sixteen 45 - caliber guns , all mounted in casemate s clustered around the forward and aft main battery turrets . " Caio Duilio " was also armed with thirteen 50 - caliber guns and six 76 - mm anti - aircraft guns . As was customary for capital ship s of the period , she was equipped with three submerged torpedo tube s . She was protected with Krupp cemented steel manufactured by U . S . Steel . The belt armor was thick and the main deck was thick . The conning tower and main battery turrets were protected with worth of armor plating . Modifications . " Caio Duilio " was heavily rebuilt in 1937 – 1940 at Genoa . Her forecastle deck was extended further aft , until it reached the mainmast . The stern and bow were rebuilt , increasing the length of the ship to , and the displacement grew to . Her old machinery was replaced with more efficient equipment and her twenty boilers were replaced with eight oil - fired models ; the new power plant was rated at and speed increased to . The ship ' s amidships turret was removed and the remaining guns were bored out to . Her secondary battery was completely overhauled ; the 152 mm guns were replaced with twelve guns in triple turrets amidships . The anti - aircraft battery was significantly improved , to include ten guns , fifteen guns , and sixteen guns . Later , during World War II , four more 37 mm guns were installed and two of the 20 mm guns were removed . After emerging from the modernization , " Caio Duilio " s crew numbered 35 officers and 1 , 450 enlisted men . Service history . " Caio Duilio " was laid down at navy dockyard in Castellammare di Stabia on 24 February 1912 . She was launched on 24 April 1913 , and completed on 10 May 1916 . She saw no action in World War I , given the fact that the Austro - Hungarian fleet , Italy ' s main naval rival , remained in port for the duration of the conflict . As a result , " Caio Duilio " only went on four patrols during the war , and was operational for a total of 70 hours . She was based at Taranto starting in November 1918 to April 1919 , but during that time , she deployed to Corfu , from 10 November 1918 to 26 January 1919 . On 26 April 1919 , " Caio Duilio " was sent to Izmir to help mediate a dispute over ownership of the area . While there , she had a confrontation with the Greek armored cruiser , but this was defused when the Greeks landed troops to occupy Izmir . On 9 June , she was relieved by the old pre - dreadnought battleship , allowing her to move to Constantinople . During her deployment to Turkey , " Caio Duilio " entered the Black Sea to support the White Russians in the Russian Civil War , from 23 June to 13 July . During this period , she was transferred to the Levant Squadron of the Italian Navy . She returned to Izmir after completing her deployment to the Black Sea , and remained there until 9 September , when she was relieved by the battleship . She returned to Taranto on 12 September , and was placed in reserve . Placed back into service in 1920 , " Caio Duilio " went to Albania on 30 June to support the Italian Army contingent occupying the country , and participated in their withdrawal on 5 September . The following year , she was assigned to the Dodecanese Squadron and cruised in the eastern Mediterranean . She returned to Constantinople as part of an Allied fleet from 27 July to 10 November 1921 . During the 1923 Corfu incident with Greece , the Italian Navy , including " Caio Duilio " , was deployed to the island to secure a Greek apology following the murder of Enrico Tellini and four others . Later that year , she escorted the battleship on a state visit to Spain . A magazine explosion on 8 April 1925 wrecked the No . 3 turret ' s barbette hoist . The ship went into reserve while repairs were effected in La Spezia , which lasted until April 1928 . She underwent refitting at Taranto from 18 March to 15 June 1930 . She again went into reserve on 11 August 1932 until 11 August 1933 , when she was made the flagship of the Commanding Officer , Reserve Fleet . Starting on 19 March 1937 , she was taken to Genoa where an extensive reconstruction began at the Cantieri del Tirreno shipyard . The work was completed on 15 July 1940 , at which point she was recommissioned into the 5th Division of the 1st Squadron , based in Taranto . " Caio Duilio " s first wartime patrol took place on 31 August . She and the rest of the fleet sailed to intercept the British battleship , which was steaming to Alexandria , and a convoy sailing to Malta . The Italian fleet did not have sufficient aerial reconnaissance , which , along with bad weather , prevented the Italians from locating the British forces . They put back in to Taranto on 1 September . " Caio Duilio " again put to sea on 7 September , in an attempt to catch the British Force H , but the Italian intelligence was faulty , as Force H was in the process of attacking Dakar . " Caio Duilio " returned to Taranto , where she remained until early November . Attack at Taranto . On the night of 10 – 11 November , the British Mediterranean Fleet launched a surprise air raid on the harbor in Taranto . Twenty - one Swordfish torpedo bombers launched from the aircraft carrier attacked the Italian fleet in two waves . They scored one hit on " Caio Duilio " , three hits on , and one on . The torpedo hit " Caio Duilio " on her starboard side ; it tore an hole in the hull and flooded the forward main battery magazines . A water tanker and several smaller craft pushed the battleship aground in shallow water to prevent her from sinking in the harbor . Temporary repairs were effected , and in January 1941 , she was refloated and sent to Genoa for permanent repairs , which began on 26 January . While " Caio Duilio " was in dock for repairs , the British Force H departed from its normal role as a convoy escort in the western Mediterranean in early February to attack Genoa . Admiral James Somerville ' s surface ships fired over a thousand shells at the port , and the aircraft of the carrier dropped magnetic mines in the harbor . Five ships were sunk , but " Caio Duilio " was not hit in the attack . During the attack , " Caio Duilio " s anti - aircraft battery fired some 8 , 000 rounds at the British spotter aircraft . Repair work was completed by May , and on 16 May she was back in Taranto in the 1st Squadron . Later service . " Caio Duilio " , now the flagship of the Italian fleet , sailed on 29 November to cover an Italian convoy to North Africa . She was escorted by the cruiser and six destroyer s . She sailed again on 13 December , to cover the convoy M41 ; the Italian fleet was forced to break off the convoy escort after was torpedoed . " Caio Duilio " returned to port on the 14th , and departed to cover the convoy M42 two days later . She was stationed south of Messina with three cruisers and four destroyers . During the convoy operation , British forces attacked , resulting in the First Battle of Sirte , but " Caio Duilio " s group was too far away to engage the British . She returned to Taranto on 19 December . She escorted convoy M43 on 3 – 6 January 1942 , which successfully reached Tripoli unmolested . Convoy T18 followed on 22 – 5 January , and four of the five transports in the convoy reached Tripoli . " Caio Duilio " s next operation was an attack on British convoys in the Mediterranean in February . She left port on 14 February with a pair of light cruiser s and seven destroyers , but the force could not locate the British ships , and so returned to port . On the 21st , she escorted the convoy K7 from Messina and Corfu to Taranto . By this point in 1942 , the Italian fleet began to suffer a severe shortage of fuel , which curtailed its operations . The situation was so bad that " Caio Duilio " had to be placed in reserve and drained of fuel , in order to keep the escort craft operational . She was at Taranto when Italy surrendered to the Allies in September 1943 , and on 9 September she was taken to Malta , where she was interned with the rest of the Italian fleet . In June 1944 , the Allies allowed " Caio Duilio " to return to Italian ports ; she spent the rest of the war in Taranto , Syracuse , and Augusta . She survived the war , and continued to serve in the Italian navy ; she was the fleet flagship from 1 May 1947 until 10 November 1949 , based in Taranto . She was moved to La Spezia in 1953 and removed from active service . " Caio Duilio " remained there until she was stricken from the naval register on 15 September 1956 . She was sold for scrapping the following year .