During World War I, "Viribus Unitis" took part in the flight of the German warships and . In May 1915, she also took part in the bombardment of the Italian port city of Ancona. "Viribus Unitis" was sunk while at anchor by a limpet mine planted by Raffaele Rossetti, an Italian engineer and naval officer of the "Regia Marina", and Raffaele Paolucci, an Italian surgeon and naval officer, on 1 November 1918.