They would go horseback-riding together in Berlin's wooded Grunewald, where they would discuss the future of Nazi Germany.[69] Often present at these equestrian outings were Heydrich and Werner Best.[70] Their alleged friendship aside, Canaris was careful around Schellenberg, a man whose ambitions included controlling all intelligence for the Reich.[71] Like Heydrich, Schellenberg ultimately envisioned a centrally directed "all-embracing security system" and a singular "Greater German Intelligence Service" under direct Nazi control (unlike the Abwehr, which was part of the Wehrmacht).[72] Nonetheless, there are indications that Schellenberg preferred to deal with Canaris' Abwehr over the Gestapo, particularly since he distrusted its chief, Heinrich Müller.[73] However, after the attempted assassination of Hitler on 20 July 1944, the Abwehr was dissolved and the SD was given additional powers over intelligence across the Reich.[74][lower-alpha 3] Canaris was arrested on 23 July 1944 on the basis of the interrogation of his successor at military intelligence, Georg Hansen.[75]