Complex sentence: Reportedly, Schellenberg and Wilhelm Canaris, the head of the "Abwehr" (military intelligence) were friends, as the two men would go horseback-riding together in Berlin's wooded Grunewald where they would discuss the future of Nazi Germany.
Split into simpler sentences: Reportedly, Schellenberg and Wilhelm Canaris, the head of the "Abwehr" (military intelligence) were friends. They would go horseback-riding together in Berlin's wooded Grunewald, where they would discuss the future of Nazi Germany.