After the outbreak of the Second World War, Dulles was recruited to work at the Office of Strategic Services and moved to Bern, Switzerland, where he lived at Herrengasse 23 for the duration of World War II.
Although Washington barred Dulles from making firm commitments to the plotters of the 20 July 1944 attempt to assassinate Hitler, the conspirators nonetheless gave him reports on developments in Germany, including sketchy but accurate warnings of plans for Hitler's V-1 and V-2 missiles.