The Medusa-class of submarines were eight submarines built for Italy and one for Portugal from 1911–1913. They displaced 305 tons while submerged, and could travel as fast as eight knots. The class consisted of the Vellella, Medusa, Argo, Jalea, Espadarte (built for Portugal), Fisalia, Zoea, Salpa, and Jantina. Two of the ships were destroyed during the First World War, both in 1915: Medusa was torpedoed by the SM UB-15 on 10 June, and on 17 August the Jalea hit a mine and sank. In 1918, the other five Italian submarines were stricken, while the Espadarte was in service until 1931.^[1]