President Franklin D. Roosevelt was urgently informed, but the United States did not pass this information to any concerned governments in Europe. A week later the plan was realised with the German invasion of Poland and the Second World War began. According to the website of the German embassy in London, Herwarth and his superior, Ambassador von der Schulenburg, had already been trying since before the Munich Agreement to persuade Britain, France and the United States not to give in to Hitler's territorial demands. Hans von Herwarth was the chief contact from the German embassy in Moscow to the western powers. Through him, the British were continuously informed on the progress of Soviet-German contacts during 1939. Von Herwarth is also held to be one of the German officials who informed the Allies on the decision to launch Operation Barbarossa in 1941, and to have given some of the earliest accounts of atrocities against Jews and other civilians behind the Eastern Front and in the Holocaust. It's not known how much his Soviet counterparts were informed. Herwath was one of the leading players in the Konigswinter conference that was organised by Lilo Milchsack that healed the bad memories after the end of the Second World War. He worked with the ex soldier Fridolin von Senger und Etterlin, future German President Richard von Weizsäcker and other leading German decision makers as well as leading British politicians like Dennis Healey, Richard Crossman and the journalist Robin Day. In June 1989, Hans von Herwarth met the Latvian historian and member of the Soviet parliament, Mavriks Vulfsons, during the latter's visit to West Germany. Vulfsons was the first person in the USSR to publicly confirm the authenticity of the secret protocols to the German-Soviet pact of 1939 dividing Eastern Europe into "spheres of influence", a copy of which he obtained in the archives of the German Foreign Office.