 Built at Kiel in 1935, "U-6" was a prestigious position for a captain in the "Kriegsmarine" during the years running up to the war, her commanders were all First World War veterans.On 31 August 1939, before the outbreak of World War II, the U-6 spotted three destroyers of the Polish Navy, the "Burza", "Błyskawica", and "Grom", executing Peking Plan, on their way to Great Britain, but no action was undertaken.However, once war began, it was painfully clear that "U-6" and her sisters were not capable of competing with other nations' larger and faster boats, and so after an initial patrol in the Baltic Sea, "U-6" was not deployed again until March 1940, when every ship available to the "Kriegsmarine" was sent to support the invasion of Norway.