sentences:  On November 21, 1990 Swiss authorities declared the dissolving of P-26, since the clandestine organization operated outside of parliamentary and even governmental control, being an autonomous structure hidden inside the secret military services.As the United Kingdom, which had prepared itself for a Nazi invasion during World War II, which led to the creation of the Home Guard and of stay-behind Auxiliary Units, Switzerland also prepared for such an eventuality, as its neutrality by itself did not constitute a sufficient guarantee against a military offensive of Nazi Germany or Fascist Italy (see 1940 Battle of Belgium).Thus, General Henri Guisan put in place the "Reduit Concept," according to which the best strategy for the military was to retreat in the highest parts of the Alps and abandon the plains to the enemy.