Klas Horn (ex-Posadnik) was the flagship and an escort ship for the Russian Czar's yacht. Posadnik was built in Prussia in 1892 for the Montenegrin king Nicholas I. The ship was purchased by the Russian Czar after Nicholas' money ran out. After the Russian revolution, the ship was taken over by the Finnish Navy and renamed Klas Horn, after a 16th-century admiral. She initially served as a minelayer, but was rebuilt into a gunboat in the 1920s. Klas Horn ended her Finnish navy service in the 1930s and served as a mothership for sea surveying.