German strongholds during World War II (German: Festung "fortresses") were the selected towns and cities so designated by Adolf Hitler to resist the Allied offensives where the defenders were ordered to defend them at all costs. The doctrine of these strongholds evolved towards the end of World War II, when the German leadership had not yet accepted defeat, but had begun to realize that drastic measures were required to forestall inevitable offensives on the Reich. The first such stronghold became Stalingrad (Battle of Stalingrad).
Subsequently, on the Eastern Front, Warsaw, Budapest, Kolberg, Königsberg, Küstrin, Danzig and Breslau were some of the large cities selected as strongholds whilst on the Western Front locations included the British island of Alderney.
The fate of the strongholds varied. Stalingrad, the first of the "fortresses" to fall is seen as a crucial turning point in the war, and one of the key battles which led to German defeat. In several cases (Breslau and Alderney, for example) the fortresses were bypassed by the attackers and did not actually fall until long after they had been neutralised (although the fighting in Breslau was sustained).