Following the West German federal election of 1969, Bahr became Secretary of State of the German Chancellery as well as "Bevollmächtigter" (“commissioner” or “appointed representative”) of the Federal Cabinet of Germany in Berlin. It was in this capacity that Bahr served as an emissary to and negotiator with Moscow with respect to the 1970 Treaty of Moscow and the 1970 Treaty of Warsaw, as well as the Transit Treaty of 1971 and the Basic Treaty of 1972 that were concluded with the German Democratic Republic. On the basis of his success in guiding these treaties to successful conclusion, Bahr is often referred to as “Architect of the Eastern Treaties”. He is also credited with two of the Brandt government's most influential mottos describing West Germany's relationship with the German Democratic Republic, “"Wandel durch Annäherung"” ("change through rapprochement", a speech at the Evangelische Akademie Tutzing) and “"Politik der kleinen Schritte"” (“policy of small steps”).