The Tegetthoff class (also called the Viribus Unitis class) was a class of four dreadnought battleships built for the Austro-Hungarian Navy. Named for Austrian Admiral Wilhelm von Tegetthoff, the class was composed of , , , and . Construction started on the ships shortly before World War I; Viribus Unitis and Tegetthoff were both laid down in 1910, Prinz Eugen and Szent István followed in 1912. Three of the four warships were built in the Stabilimento Tecnico Triestino shipyard in Trieste; Szent István was built in the Ganz-Danubius shipyard in Fiume, so that both parts of the Dual Monarchy would participate in the construction of the ships. The Tegetthoff-class ships hold the distinction for being the first and only dreadnought battleships of the Austro-Hungarian Navy. The SMS Szent István had a different more modern propulsion system than her sister ships. Viribus Unitis and Tegetthoff were commissioned into the fleet in December 1912 and July 1913, respectively. Prinz Eugen followed in July 1914. The smaller shipyards in Fiume resulted in a slower construction which was further delayed by the outbreak of the war, with Szent István commissioned into the fleet in December 1915. This was too late for her to take part in the Bombardment of Ancona in which the remaining ships in the class saw action immediately following Italy's declaration of war on Austria-Hungary in May 1915. All of the Tegetthoffs were members of the 1st Battleship Division at the beginning of the war and were stationed out of the naval base at Pola. Following the Bombardment of Ancona and the commissioning of Szent István, the four ships saw little combat due to the Otranto Barrage which prohibited the Austro-Hungarian Navy from leaving the Adriatic Sea. In June 1918, in an attempt 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 Szent István was sunk by the Italian motor torpedo boat MAS-15 on the morning of 10 June. After the sinking of Szent István, the remaining three ships of the class returned to port in Pola where they remained for the rest of the war. When Austria-Hungary was facing defeat in the war in October 1918, the Austrian government decided to transfer Viribus Unitis to the newly formed State of Slovenes, Croats and Serbs in