The locations are known in German as Atlantikfestungen (lit. "Atlantic strongholds") but are known in English as "Atlantic pockets".
Six of the Atlantic pockets were captured by the Allies between June and October 1944. Others were placed under siege. Three surrendered in April 1945, and the remainder in May 1945.
Designation as fortresses
On 19 January 1944 Adolf Hitler declared eleven places along the Atlantic Wall to be fortresses (Festungen), to be held until the last man or the last round, calling them Atlantikfestungen (lit. "Atlantic strongholds").[1]
Other fortresses were added after D-Day on 6 June 1944 in further directives of 17 August and 4 September.[citation needed]
Purpose
As well as concentrating men and matériel to control the surrounding area, the fortresses' purpose was to deny the use of port facilities to the Allies and to secure their continued use by German submarines in the Battle of the Atlantic. In addition, as long as they remained in German hands, they had propaganda value.
Fate of the pockets
In France, six pockets were captured by the Allies between the initial invasion of Normandy in June 1944 and October 1944, and others brought under siege. Three were liberated by French forces in April 1945, while the remainder surrendered after the capitulation of Germany in May 1945.
List of Atlantic pockets
The Atlantic pockets, with the date any Allied assault began and date the defenders surrendered, are shown below.
^The island of Cézembre held out until 2 September 1944
References
Rémy Desquesnes. Les poches de résistance allemandes sur le littoral français: août 1944 – mai 1945. Rennes: Éd. Ouest-France, 2011. ISBN978-2-7373-4685-9; (in French).
(fr) Stéphane Simonnet (2015), Les poches de l'Atlantique: Les batailles oubliées de la Libération Janvier 1944 - mai 1945, Tallandier, ISBN979-10-210-0492-4