When was the the ship launched ,that along with the Tripitz and the Lützow was a target for  Operation Source ?
Operation Source Operation Source was a series of attacks to neutralise the heavy German warships – "Tirpitz", "Scharnhorst" and "Lützow" – based in northern Norway, using X-class midget submarines.
German submarine U-31 (1936) German submarine "U-31" was a Type VIIA U-boat of Nazi Germany's "Kriegsmarine" during World War II. She was laid down on 1 March 1936 as yard number 912, launched on 25 September and commissioned on 28 December 1936.