 = SM U @-@ 3 ( Austria @-@ Hungary ) = 
 
 SM U @-@ 3 or U @-@ III was the lead boat of the U @-@ 3 class of submarines or U @-@ boats built for and operated by the Austro @-@ Hungarian Navy ( German : Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine ) before and during the First World War . The submarine was built as part of a plan to evaluate foreign submarine designs , and was built by Germaniawerft of Kiel , Germany . 
 U @-@ 3 was authorized in 1906 , begun in March 1907 , launched in August 1908 , and towed from Kiel to Pola in January 1909 . The double @-@ hulled submarine was just under 139 feet ( 42 m ) long and displaced between 240 and 300 tonnes ( 260 and 330 short tons ) , depending on whether surfaced or submerged . The design of the submarine had poor diving qualities and several modifications to U @-@ 3 's diving planes and fins occurred in her first years in the Austro @-@ Hungarian Navy . Her armament , as built , consisted of two bow torpedo tubes with a supply of three torpedoes , but was supplemented with a deck gun in 1915 . 
 The boat was commissioned into the Austro @-@ Hungarian Navy in September 1909 , and served as a training boat — sometimes making as many as ten cruises a month — through the beginning of the First World War in 1914 . At the start of that conflict , she was one of only four operational submarines in the Austro @-@ Hungarian Navy U @-@ boat fleet . Over the first year of the war , U @-@ 3 conducted reconnaissance cruises out of Cattaro . On 12 August 1915 , U @-@ 3 was damaged after an unsuccessful torpedo attack on an Italian armed merchant cruiser and , after she surfaced the next day , was sunk by a French destroyer . U @-@ 3 's commanding officer and 6 men died in the attack ; the 14 survivors were captured . 
 
 = = Design and construction = = 
 
 U @-@ 3 was built as part of a plan by the Austro @-@ Hungarian Navy to competitively evaluate foreign submarine designs from Simon Lake , Germaniawerft , and John Philip Holland . The Austro @-@ Hungarian Navy authorized the construction of U @-@ 3 ( and sister ship , U @-@ 4 ) in 1906 by Germaniawerft of Kiel , Germany . U @-@ 3 was laid down on 12 March 1907 and launched on 20 August 1908 . After completion , she was towed via Gibraltar to Pola , where she arrived on 24 January 1909 . 
 U @-@ 3 's design was an improved version of Germaniawerft 's design for the Imperial German Navy 's first U @-@ boat , U @-@ 1 , and featured a double hull with internal saddle tanks . The Germaniawerft engineers refined the design 's hull shape through extensive model trials . 
 U @-@ 3 was 138 feet 9 inches ( 42 m ) long by 14 feet ( 4 @.@ 3 m ) abeam and had a draft of 12 feet 6 inches ( 3 @.@ 81 m ) . She displaced 240 tonnes ( 260 short tons ) surfaced and 300 tonnes ( 330 short tons ) submerged . She was armed with two bow 45 @-@ centimeter ( 17 @.@ 7 in ) torpedo tubes , and was designed to carry up to three torpedoes . 
 
 = = Service career = = 
 
 After U @-@ 3 's arrival at Pola in January 1909 , she was commissioned into the Austro @-@ Hungarian Navy on 12 September 1909 as SM U @-@ 3 . During the evaluation of the U @-@ 3 class conducted by the Navy , the class ' poor diving and handling characteristics were noted . To alleviate the diving problems , U @-@ 3 's fins were changed in size and shape several times , and eventually , the front diving planes were removed and a stationary stern flap was affixed to the hull . U @-@ 3 served as a training boat between 1910 and 1914 and made as many as ten cruises per month in that capacity . 
 At the beginning of World War I , she was one of only four operational submarines in the Austro @-@ Hungarian Navy . On 22 August 1914 , U @-@ 3 began operating reconnaissance cruises out of the naval base at Brioni , but moved a month later to Cattaro . In April 1915 , a 3 @.@ 7 @-@ centimeter ( 1 @.@ 5 in ) quick firing ( QF ) deck gun was added . 
 On 10 August , U @-@ 3 departed from Cattaro for what would be her final time for a patrol north of Brindisi . Two days later , while returning to Cattaro from the Straits of Otranto , U @-@ 3 launched a torpedo attack on the Italian armed merchant cruiser Citta di Catania . The torpedoes missed their mark and , in the ensuing action , U @-@ 3 was rammed by Citta di Catania , which destroyed the U @-@ boat 's periscope . When she attempted to surface , she was shelled by the escorting destroyers . She submerged to escape the artillery but was further damaged by a depth charge attack from the French destroyer Bisson while resting on the seabed . When U @-@ 3 surfaced the following day , she was shelled and sunk by Bisson . Fourteen of her crew were saved and captured , but seven died in the attack , including her commander , Linienschiffsleutnant Karl Strnad . U @-@ 3 had no successes during the war . 
 
 