 As it became apparent that the ground was being cleared, especially within the Soviet occupation zone, for a return to one-party dictatorship under the Socialist Unity Party of Germany, Birkenfeld was taking am increasingly public position against Communism, at least from the launch of the Berlin Blockade in June 1948, and possibly earlier.On 19 September 1948 he was a co-founder of the "League for Spiritual Freedom" ("Liga für Geistesfreiheit").Early in 1949 he was a co-founder of the anti-communist Combat Group against Inhumanity ("Kampfgruppe gegen Unmenschlichkeit").