Commissioned into the Austro-Hungarian Navy just 10 days after the assassination of Archduke Franz Ferdinand, "Prinz Eugen" 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. She 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 prevented 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 "Prinz Eugen"s sister ship, , was sunk by torpedoes launched from the Italian torpedo boat "MAS-15" on 10 June.