UB @-@ 1 and the still incomplete UB @-@ 15 were sold to the Austria @-@ Hungary in February 1915 ; both were dismantled and shipped to Pola in May . After one cruise under the German flag , each boat was commissioned into the Austro @-@ Hungarian Navy . The pair — renamed U @-@ 10 and U @-@ 11 , respectively — were joined by U @-@ 15 , U @-@ 16 , and U @-@ 17 in October . Known as the U @-@ 10 or the Okarina ( English : Ocarina ) class as a part of the Austro @-@ Hungarian Navy , the five boats operated primarily in the Adriatic in patrols off Italy and Albania . U @-@ 10 ( ex UB @-@ 1 ) hit a mine in July 1918 and was beached , but had not been repaired by the end of the war . U @-@ 16 was sunk after she torpedoed an Italian destroyer in October 1916 , and the remaining three ( and the unrepaired U @-@ 10 ) were ceded to Italy at the end of the war .