Dulles was in contact with the Austrian resistance group around the priest Heinrich Maier, who collected information through many different contacts with scientists and the military. From 1943 onwards, he received very important information from this resistance group about V-1, V-2 rockets, Tiger tanks, Messerschmitt Bf 109, Messerschmitt Me 163 Komet and other aircraft and the related factories. Allied bombers were thus able to target war-decisive armaments factories. In particular, Dulles then had crucial information for Operation Crossbow and Operation Hydra. The group reported to him about the mass murder in Auschwitz. Through the Maier Group and Kurt Grimm, Dulles also received information about the economic situation in the Nazi sphere of influence. After the resistance group was uncovered by the Gestapo, Dulles sent American agents to Austria to contact any surviving members.