The Alpine Fortress or Alpine Redoubt was the World War II German national redoubt planned by Reichsführer-SS Heinrich Himmler in November and December 1943. Plans envisaged Germany's government and armed forces retreating to an area from "southern Bavaria across western Austria to northern Italy". The scheme was never fully endorsed by Hitler, and no serious attempt was made to put it into operation, although the concept served as an effective tool of propaganda and military deception carried out by the Germans in the final stages of the war. After surrendering to the Americans, the Wehrmacht General Kurt Dittmar told them that the redoubt never existed.

A national redoubt or national fortress is an area to which the (remnant) military forces of a nation can be withdrawn if the main battle has been lost or even earlier if defeat is considered inevitable. Typically, a region is chosen with a geography favouring defence, such as a mountainous area or a peninsula, to function as a final holdout to preserve national independence and host an effective resistance movement for the duration of the conflict.