 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 . 
