After the invasion of Norway, the Kriegsmarine captured four torpedo boats of the Norwegian Sleipner class, which were modern
ships just commissioned before the war. Being quite small vessels, the ships were not used for combat action but for U-boat training in the Baltic Sea since 1942.  After the war, all four ships were returned to Norway were they first served as training vessels, but were later refitted as patrol boats with reduced armament and boiler poweer.

The Balder was taken over by the Kriegsmarine while being equipped at the shipyard on 09.04.1940. Commissioned on 26.7.1940 as Leopard it was also reclassified as a Torpedofangboot in January of 1942. Returned to Norway in 1949 it was converted into an escort vessel and scrapped in 1962.