German Flakschiff Undine

What would become the Flakschiff Undine was launched in 1906 as the Dutch coastal defence ship HNLMS Jacob van Heemskerck.

By the start of World War Two, HNLMS Jacob van Heemskerck’s active career was over and the ship had her machinery removed and was converted into a floating battery ship renamed Batterijschip IJmuiden. After the German invasion, her crew scuttled the ship on 14 May 1940 to prevent her capture. However, on 16 July 1940 she was raised and towed to Amsterdam. From her she was moved to Kiel and converted into a floating anti-aircraft battery and renamed Undine.

Post-war she was found at Wilhelmshafen and returned to Dutch control. The ship was rebuilt as an accommodation ship and recommissioned on 23 February 1948. She was again renamed, this time as Neptunus. Neptunus performed this role until 13 September 1974 when she was decommissioned.