Ariadne

The invasion of the Netherlands provided the Kriegsmarine with several older Dutch warships, and some of them were taken into service again.

The old coastal battleships Jakob van Heemskerck (commissioned 1906) and Hertog Hendrick (commissioned 1902) were sunk by dutch forces in May 1940, but raised by the Germans in 1941 and transferred to Kiel to reconstruct them as Floating AA batteries. The Jacob van Heemskerck was renamed as Undine.

With their eight 10,5 cm heavy AA guns, both ships were among the heaviest armed floating AA batteries and were equipped with the most up to date Radar equipment available, the so called "Würzburg-Funkmeßgerät". The obsolete engines were put out of service, therefore the ships had to be towed to their operational areas. The ships only kept its generators to supply the on board systems with power.

The Ariadne was first used in the German Beight, from August 1944, the battery was moved to the area of Danzig and Gotenhafen (Gdynia). In 1945 it was given back to the Netherlands where it was converted into a floating barrack named. If was scrapped after 1955.