Radetzky - class battleship The " Radetzky " class was a group of three semi - dreadnought battleship s built for the Austro - Hungarian Navy between 1907 and 1910 . All ships were built by the STT shipyard in Trieste . They were the last pre - dreadnoughts built by the Austro - Hungarians , and the penultimate class of any type of Austro - Hungarian battleship completed . The class comprised three ships : , , and . They were armed with four 30 . 5 centimeter ( 12 inch ) guns in two twin turrets and eight 24 cm ( 9 . 4 in ) guns in four twin turrets ; the heavy secondary guns set the " Radetzky " - class ships apart from other pre - dreadnought type battleships . Commissioned only a few years before the outbreak of World War I , the ships had limited service careers . All three of the battleships conducted training cruises in the Mediterranean Sea in 1912 . In 1913 , they took part in an international naval demonstration in the Ionian Sea that protested the Balkan Wars . After Italy declared war on Austro - Hungary and the other Central Powers in 1915 , the three " Radetzky " - class ships bombarded coastal targets in the Adriatic Sea . After 1915 , their participation in the war became minimal . All three ships were handed over to Italy after the end of the war , and broken up for scrap between 1920 and 1926 . Design . Development . Design work for a new class of battleships started about two weeks after the launching of , an , which took place on April 30 , 1904 . By the end of July 1905 , the Austrian Commander in Chief of the Navy , Admiral Monteccuccoli , laid out his vision for an expanded Austro - Hungarian fleet . This included 12 battleships , four armored cruiser s , eight scout cruisers , 18 destroyer s , 36 large torpedo boat s , and six submarine s . A navy design board evaluated five designs for the new battleship type between September 25 – 29 , 1905 . The first design was armed with four 28 cm ( 11 in ) guns in two twin turrets , four 24 cm ( 9 . 4 in ) guns in single turrets , and eight 19 cm ( 7 . 5 in ) guns in casemates . The second design retained the 28 and 24 cm guns as in the first version , though altered the tertiary guns to twelve 10 cm guns . The third design , representative of the new dreadnought type of battleship that was being contemplated in other navies , featured eight 28 cm guns in four twin turrets , one fore , one aft , and two wing turrets . The heavy secondary guns were dispensed with altogether , and the light - caliber guns were increased to sixteen 10 cm guns . The fourth design was a variation on the third type ; the eight 28 cm guns were replaced by six 30 . 5 cm ( 12 in ) guns , in two twin turrets and two single turrets . The 10 cm guns remained the same . The final design mounted four 30 . 5 cm guns in two twin turrets , eight 19 cm guns in four wing turrets , and twelve 10 cm guns in casemates . The leader of the design staff , Siegfried Popper , advocated the construction of an " all - big - gun " ship . However , Austro - Hungarian dock facilities at the time limited displacement to ; the two " dreadnought " type designs were too heavy . Popper eventually relented , after admitting that the larger dreadnought type design would also warrant the construction of a new floating dry dock , which would significantly increase the cost of the project . The design board selected the fifth design , though during refinement of the design , the secondary guns were increased in caliber from 19 cm to 24 cm . The 30 . 5 cm gun was chosen because the breech of the new 28 cm was unreliable . The resulting design was the last pre - dreadnought type of battleship built by the Austro - Hungarian navy . Underwater protection was also emphasized . Between August and November 1906 , the Austro - Hungarian navy conducted explosive tests using the 50 - year old ironclad . The tests were conducted with , in an attempt to investigate blast effects of the standard naval mine on a 1 : 10 scale . The tests were generally unsuccessful ; as a result , Popper devised a mathematical model to predict the strength the underwater protection system would require to adequately protect the new battleships . The ships were ultimately equipped with an armored double bottom for defense against mines and torpedoes . General characteristics . The " Radetzky " - class ships were 137 . 5 m ( 450 ft 11 in ) long at the waterline and 138 . 8 m ( 455 ft 4 in ) long overall . They had a beam of 24 . 6 m ( 80 ft 8 in ) and a draft of 8 . 1 m ( 26 ft 9 in ) . The ships were designed to displace normally , and up to with a full combat load . Machinery consisted of two four - cylinder vertical triple expansion engines . Each engine was powered by six Yarrow boilers . Power output was 19 , 800 indicated horsepower , for a top speed of . The ships carried of coal , which enabled a maximum range of at a cruising speed of . Armament . The " Radetzky " - class ships , as noted above , carried a main battery of four 30 . 5 cm ( 12 in ) 45 - caliber guns in two twin gun turret s . The guns were built by Škoda Works in Pilsen . They were capable of a rate of fire of three shells in the first minute , and then 1 to 2 rounds per minute afterward . The guns fired armor - piercing ( AP ) shells that weighed 450 kg ( 992 lb ) and required a 138 kg ( 304 lb ) propellant charge . Their muzzle velocity was 800 meters per second ( 2 , 625 fps ) . The turrets could depress to −3° and elevate to 20° . At maximum elevation , the guns could hit targets out to 20 , 000 m ( 21 , 870 yards ) . These turrets suffered from a number of design faults ; among them were the overly - large cupolas on top . If a cupola was struck by gunfire , the thin top armor could be peeled back . Another serious issue was a defect in the ventilation system : when the turret was being ventilated under combat conditions , the system would duct toxic propellant gases into the gun house . It was estimated that the turrets contained only 15 minutes of oxygen once the ventilation system was activated . The ships carried a heavy secondary battery of eight 24 cm ( 9 . 4 in ) guns in four twin turrets . The turrets were mounted amidships , two on either side . These guns had nearly half the penetration power of the larger 30 . 5 cm guns , and approximately 25 % shorter range . The secondary armament was augmented by twenty 10 cm L / 50 guns in single mounts . These guns fired 26 . 2 kg ( 57 . 7 lb ) shells at a rate of between 8 and 10 rounds per minute . The shells were fired at a muzzle velocity of 880 mps ( 2 , 790 fps ) and could hit targets out to 11 , 000 m ( 12 , 030 yd ) . " Radetzky " and her sisters also carried several smaller caliber guns , including two 66 mm ( 2 . 6 in ) landing guns , four 47 mm ( 1 . 85 in ) L / 44 and one 47 mm L / 33 quick - firing guns . Three 45 cm ( 17 . 7 in ) torpedo tubes were also carried , two on the beams and one in the stern . Armor . The ships had an armored belt that was thick in the central portion of the ship , where it protected the ammunition magazines , machinery spaces , and other critical areas of the ship . Forward and to the rear of the main battery barbette s , the belt reduced in thickness to . A thick torpedo bulkhead ran the length of the hull to provide a second layer of underwater protection should the main belt be penetrated . The armored deck was thick , and supported by a sloped deck that was also 48 mm thick . The main battery turrets were heavily armored . Their sides and face were thick , while their roofs were thick . The turrets for the secondary 24 cm guns had slightly less armor , with thick sides and thick roofs . The casemate s that mounted the 10 cm guns were protected with worth of armor plating . The armored conning tower had 250 mm - thick sides and a 100 mm - thick roof . Construction Program . All three ships were built by the STT shipyard in Trieste . Service careers . Pre - war . The three " Radetzky " - class battleships were assigned to the 2nd Division of the 1st Battle Squadron , alongside the " Tegetthoff " ships in the 1st Division . The three ships conducted several training cruises in the Mediterranean Sea after their commissioning in 1910 – 11 . " Radetzky " was present during the British Coronation Review at Spithead in 1911 . In 1912 , " Zrínyi " took part in a training cruise with the recently commissioned dreadnoughts and in the eastern Mediterranean , which included a stop at Malta . The following year , the three ships were involved in an international naval demonstration to protest the raging Balkan Wars ; during the operation the first seaplane s to be launched from a warship in combat were operated from " Radetzky " and her sisters . World War I . The assistance of the Austro - Hungarian fleet was called upon by the German Mediterranean Division , which consisted of the battlecruiser and light cruiser . The German ships were attempting to break out of Messina , where they had been coaling prior to the outbreak of war — British ships had begun to assemble off Messina in an attempt to trap the Germans . By this time , the Austro - Hungarians had not yet fully mobilized their fleet , though the three " Radetzky " s and three s , along with several cruisers and smaller craft , were available . The Austro - Hungarian high command , wary of instigating war with Great Britain , ordered the fleet to avoid the British ships , and to only openly support the Germans while they were in Austro - Hungarian waters . On August 7 , when the Germans broke out of Messina , the Austro - Hungarian fleet , including the " Radetzky " - class battleships , sailed as far south as Brindisi , before returning to port . In October 1914 , the French army established artillery batteries on Mount Lovčen to support the Army of Montenegro against the Austrian army at Cattaro . By the time they were operational , on October 15 , the Austro - Hungarians were ready with the pre - dreadnoughts of the . However , their 24 cm guns were insufficient to dislodge the French artillery batteries , and so " Radetzky " was sent to assist them . On October 21 , the ship arrived , and the gunfire from her 30 . 5 cm guns forced the French to abandon the position . On May 24 , 1915 , all three ships bombarded the Italian coast , including the important naval base at Ancona , following the entrance of Italy into the war on the side of the Triple Entente . By October 1918 , Austria prepared to transfer her entire fleet to Yugoslavia in order to keep it out of Italian hands . On November 10 , 1918 , one day before the armistice , Yugoslav officers with scratch crews sailed " Radetzky " and " Zrínyi " out of Pola . As they cleared the breakwater at Pola , they sighted the approaching Italian fleet . The two battleships hoisted American flags and sailed south along the Adriatic coast to Castelli Bay near Spolato . They appealed for American naval forces to meet them and accept their surrender , which a squadron of USN submarine chasers in the area did . However , under the subsequent peace treaty , the Allied powers ignored the transfer of the Austro - Hungarian ships to the Yugoslav navy ; instead , the ships were to be ceded to Italy . " Radetzky " and " Zrínyi " were broken up in Italy between 1920 – 21 ; " Erzherzog Franz Ferdinand " survived until 1926 , when she too was scrapped in Italy . References . Other sources