Throughout the events leading to the Anschluß and even after the Nazis marched into Austria on 12 March 1938, Heydrich – convinced that only his SD could pull off a peaceful union between the two German-speaking nations – organized demonstrations, conducted clandestine operations, ordered terror attacks, distributed propaganda materials, encouraged the intimidation of opponents, and had his SS and SD personnel round-up prominent anti-Nazis, most of whom ended up in Mauthausen concentration camp[27] The coordinated efforts of the SiPo and Heydrich's SD during the first days of the Anschluß effectively eliminated all forms of possible political, military and economic resistance within Austria.[28] Once the annexation became official, the Austrian police was immediately subordinated to Heydrich's SD, the SS and Gestapo.[29] Machinations by the SD, the Gestapo, and the SS helped to bring Austria fully into Hitler's grasp and on 13 March 1938, he signed into law the union with Austria as tears streamed down his face.[30]