Armed with a main battery of twelve guns in four triple turrets, "Szent István" was assigned to the 1st Battleship Division of the Austro-Hungarian Navy upon her commissioning. Alongside the other ships of her class, she was stationed out of the Austro-Hungarian naval base at Pola. "Szent István"s commissioning into the fleet came too late for her to participate in the Bombardment of Ancona following Italy's declaration of war on Austria-Hungary in May 1915, and she saw little combat for the rest of the war due to the Otranto Barrage, which prevented the Austro-Hungarian Navy from leaving the Adriatic Sea.