During the final years of World War II, the Atlantic pockets were the final pockets of resistance of the Wehrmacht in occupied France. On 19 January 1944 Adolf Hitler declared fourteen places along the Atlantic Wall to be fortresses (festungen) to be held until the last man—the so-called Atlantikfestungen. Their purpose was to prevent the Allies from re-supplying their armies after the invasion of France and to secure the continued use of submarines in the Battle of the Atlantic. The last such pocket surrendered on 11 May 1945, three days after the capitulation of Germany.
In his directive of 19 January 1944, Alfred Jodl established the Atlantic fortresses in four sectors:
Subsequent to the Allied invasion on 6 June, Jodl issued further directives on 17 August and 4 September, specifying the need to defend Calais and Walcheren.
After the liberation of Brest on 19 September 1944, the Allies decided to lay siege to the remaining pockets and not to take them by force. Only Royan was subsequently assaulted, falling to French forces on 20 April 1945 during the siege of La Rochelle, which did not itself capitulate until 8 May. The remaining pockets were: