 She was launched on 9 March 1940 and commissioned on 11 June, with "Kapitänleutnant" Georg-Wilhelm Schulz in command.The core of the crew came from Schulz’s previous command, U-64, which had been sunk during the Norwegian campaign, the survivors had been rescued by Wehrmacht mountain troops and their badge, the Edelweiss, was painted on U-124’s conning tower in appreciation.He was relieved on 8 September 1941 by "Korvettenkapitän" Johann Mohr.