Sieglinde was a sonar decoy used during the Second World War by German U-boats. Sieglinde was installed in chambers on the sides of the U-boat.[1] It could be ejected to a considerable distance from the boat when attempting to hide from a seeker's sonar equipment. The Sieglinde was powered by electric motors, allowing it to move at, and to periodically ascend or dive, thus imitating the sonar return of an actual submarine. This allowed the real U-boat to slip away quietly from pursuing ships. It was typically used in combination with Pillenwerfer (or Bold) decoys.[2]