 German submarine U @-@ 36 was a Type VIIA U @-@ boat of Nazi Germany 's Kriegsmarine which served during World War II . She was constructed in the earliest days of the U @-@ boat arm at Kiel in 1936 , and served in the pre @-@ war Navy in the Baltic Sea and North Sea under Kapitänleutnant ( Kptlt . ) Klaus <unk> . Korvettenkapitän ( <unk> ) Wilhelm Fröhlich took command in October 1938 and continued in the role until the boat was lost . 
