La Rochelle

When France was defeated in June 1940, there was a hope from German side that Britain also would surrender. But the British kept on fighting, were not defeated and an invasion of the british isles was cancelled in the autumn of 1940. An alternative method of defeating the British was through submarines. These would hunt down convoys of war material and other things that sailed across the Atlantic to Britain and attacking them with torpedoes. If Britain could not be defeated militarily, they would at least be forced to their knees by choking the supply of materials that allowed them to continue the war.

The Occupation of France gave the Germans access to the French Atlantic coast and therefore opportunities to establish submarine bases. In this way the Germans came closer to the convoys than if they had to sail out of bases in Germany. From 1941, five major submarine bases were built along the Atlantic coast, Brest, Lorient, Saint Nazaire, La Rochelle and Bordeaux. The bases were gigantic concrete complexes where submarines were prepared for long missions on the Atlantic Ocean. Upon completion of the mission, the submarines returned to their bases for repairs, maintenance, replenishment of materials and supplies to later embark on new missions.

Construction of the base in La Rochelle began in April 1941 and the first two pens were completed in October of that year and the first submarine arrived in November. By April 1943, a total of 10 pens had been built. In La Rochelle, the 3rd submarine flotilla was based. The submarines were protected by meters thick concrete walls/ceiling, impossible to impregnable by allied bombings. In addition to the pens, workshops, storage rooms, mess rooms, power stations and accommodation for the crew were also built. After landing in Normandy in June 1944, the base began to be dismantled and in August the flotilla moved to Norway.