During World War II, the German Kriegsmarine did not have specifically built minelayers. Therefore, the offensive mining operations at the beginning of the war had to be executed by destroyers, torpedo boats, cruisers and submarines. It soon became obvious that the existing ships were not able to fulfill this task alone, so several civil and captured ships were modified for mine laying. 
Kreigsmarine Light Cruisers - Minenleger Projekt ==========================================================================
There were several cruise liners, and other merchant ships put into service as converted minelayers. After the invasion of Norway, the captured Norwegian minelayer Olav Trayggvason (renamed to Albatros and later to Brummer ) was the only "real" minelayer in German services.
In 1937 a group of four offensive minelayers was planned. Those ships were ordered in July 1938 and May 1939 with a projected completion date of summer 1941. Construction was never started on any of these ships and, shortly after the outbreak of World War II, all four on order were canceled.
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NB: The above text has been collected / excerpted / edited / mangled / tangled / re-compiled / etc ... from the following online sources :
KM - Cruiser Minenleger Projekt - wikipedia article #1
