During World War II, detailed invasion plans were drawn up by the Germans, but Switzerland was never attacked. Switzerland was able to remain independent through a combination of military deterrence, concessions to Germany, and good fortune as larger events during the war delayed an invasion. Under General Henri Guisan central command, a general mobilisation of the armed forces was ordered. The Swiss military strategy was changed from one of static defence at the borders to protect the economic heartland, to one of organised long-term attrition and withdrawal to strong, well-stockpiled positions high in the Alps known as the Reduit. Switzerland was an important base for espionage by both sides in the conflict and often mediated communications between the Axis and Allied powers.