"Tegetthoff" was a member of the 1st Battleship Division of the Austro-Hungarian Navy at the beginning of the war alongside the other ships of her class, and was stationed out of the Austro-Hungarian naval base at Pola. First saw action during the Bombardment of Ancona following Italy's declaration of war on Austria-Hungary in May 1915, but saw little combat for the rest of the war due to the Otranto Barrage, which prohibited the Austro-Hungarian Navy from leaving the Adriatic Sea. In June 1918, in an bid to earn safer passage for German and Austro-Hungarian U-boats through the Strait of Otranto, the Austro-Hungarian Navy attempted to break the Barrage with a major attack on the strait, but it was abandoned after "Tegetthoff" and her sister ship, were attacked by Italian motor torpedo boats on the morning of 10 June. "Tegetthoff" was unharmed during the attack, but "Szent István" was sunk by torpedoes launched from "MAS-15".