 Originally intended to be the trawler "Mannheim" for the Nordsee Deutsche Hochseefischerei, Wesermünde, she was requisitioned by the Kriegsmarine as "Externsteine".She was launched in 1944, and completed in July of that year.The ship was originally named for the unusual Externsteine rock formation investigated by Heinrich Himmler for evidence of cultural significance to early Teutonic folklore and history.