The "Mosel" was laid down as a fishing trawler in 1937 in Bremerhaven for the civilian Hans Kunkel. Two years later, in December of 1939, she was requisitioned by the Kriegsmarine and placed in a minesweeper unit. She was re-designated the M-1903 and received a military crew and light armament. She first saw service in April of 1940 during the invasion of Norway, and assisted in the rescue of the cruiser "Lützow" as well as rescuing the crew of the sunk minesweeper M-1101 "Foch &amp; Hubert".