Most of the resistance groups were soon crushed by the Gestapo. While the plans of the group around Karl Burian to blow up the Gestapo headquarters in Vienna were uncovered, the important group around the later executed priest Heinrich Maier managed to contact the Allies. This so-called Maier-Messner group was able to send the Allies information about armaments factories for V-1, V-2 rockets, Tiger tanks and aircraft (Messerschmitt Bf 109, Messerschmitt Me 163 Komet, etc.), which was important for Operation Crossbow and Operation Hydra, both preliminary missions for Operation Overlord. This resistance group, which was in contact with the American secret service OSS, soon provided information about mass executions and concentration camps such as Auschwitz. The aim of the group was to let Nazi Germany lose the war as quickly as possible and to re-establish an independent Austria.