9. Keroman Submarine Base
This historic base was constructed under Großadmiral Karl Dönitz request. While he was on the French shores of the Atlantic Ocean, he needed a base for his operations and thus four gigantic structures named K1, K2, K3, and an incomplete K4 were built in the period between February 1941 and January 1942. This German base became a starting point of numerous U-Boat operations and was particularly used to target Allied supply convoys during the U-Boat Happy Days. Because of its huge size, it was capable of sheltering about thirty undercover submarines.
During the war, several German bases became targets and were heavily damaged by Allied bombing raids. However, this naval base was able to survive through to the end of the war. The structures are said to have been difficult to destroy and even though the American Army surrounded them, the Nazi Germany army still did not back down. In that case, the Allied forces decided to flatten the town of Lorient, thus cutting the base from its main supply line.
After the war, Keroman Submarine Base was rechristened as Base Ingénieur Général Stosskopf in July 1946 by the French, who had taken control. The name was used to commemorate the death of Jacques Stosskopf, an Alsatian Frenchman, who was working as the deputy director of naval construction for the Germans at the base and secretly providing valuable information on submarine movements to the Allies during the French Resistance. When the Germans later discovered his activities, he was executed at Struthof camp in Alsace on 1 September 1944, just before the arrival of the Allies.
The base has been used as a tourist site since the French abandoned it in 1997.