 From 1859 to 1864, he was Envoy to the Kingdom of Denmark and took part in the negotiation of the 1864 Treaty of Vienna that concluded the Second Schleswig War.He served as Ambassador to Belgium from 1864 to 1871.When he was succeeded by Bernhard Ernst von Bülow as Foreign Secretary, he was appointed to the Prussian House of Lords, where he was considered a liberal peer, and returned to his post as ambassador in Brussels.