In 1940 Salinger began to take part in the activities of the anti-government resistance group headed up by the former "Young Communists" official, Herbert Baum. The group tends to be identified in subsequent sources as the "Herbert Baum Group", although that implies a level of coherence and organisation that may not have been apparent. Another group member was Salinger's fiancée, Ursel Ehrlich. After the German government suddenly repudiated the Germany's non-aggression agreement with the Soviet Union in June 1941, members of the Baum Group attempted to contribute to the military defeat of Germany, and hence of National Socialism. This meant complementing from inside Germany the external efforts of the anti-German "allied powers", of which by far the most significant from the perspective of Berlin in 1941 was the Soviet Union. That meant engaging in acts of sabotage on the home front such as producing and distributing anti-war leaflets and manifestoes. A more widely reported action was the arson attack and leafleting blitz carried out on 18 May 1942 by members of the group against the government's ironically named "Soviet Paradise" in Berlin's Lustgarten park. The physical damage caused seems to have been minimal, but the government Propaganda Ministry was quick to seize on the opportunity to label government's opponents as Communists and Jews intent on securing Soviet victory in the war. The incident was also the trigger for a wave of arrests across Berlin of anti-government activists, most of whom in this instance were communist or Jewish or both.