Allied officials used Swiss outposts to organise resistance efforts with partisans, and the nation played host to espionage networks built up from Swiss citizens and from anti-Nazi immigrants from abroad.
This included Rudolf Roessler, a German immigrant who moved to Lucerne, Switzerland in 1933 and set up a publishing house. Roessler subsequently developed connections, through travelling back and forth to Germany and through military contacts he had made whilst a solider in the First World War, with high-ranking officials in the German government and military who likewise opposed the Nazi regime.
Keen to disseminate information, they passed it to Roessler, who passed it to the Swiss Military Intelligence who in turn passed it to the British Secret Intelligence Service, though Roessler also passed information to the Russians.
Forming part of the ‘Lucy’ network (so named for Roessler’s location), his sources were so good that he was able to access military plans soon after their creation. This was exemplified by intelligence he would pass on in May 1941 regarding Operation Barbarossa, the Nazis’ planned invasion of the Soviet Union, and Operation Zitadelle, another planned attack on the Soviet Union in summer 1943. With intelligence from Roessler and others across Europe, the Soviet preparations for the latter conflict allowed them to strike a strategic blow against the Nazis.