 The first three ships , Viribus Unitis , Tegetthoff and Prinz Eugen were joined by their sister in 1915 , when they bombarded the Italian installations at Ancona . The Tegetthoffs attempted to sortie through the Otranto Barrage with the support of lighter ships in 1918 , but failed after Szent István was sunk . After the transfer to State of Slovenes , Croats and Serbs , Virbus Unitis was sunk by Italian frogmen , and Tegetthoff and Prinz Eugen were transferred to Italy and France , respectively . 
