Germany’s national anthem rests on an exchange of letters. In May 1952, after an exchange of letters between Chancellor Konrad Adenauer and President Theodor Heuss, the Lied der Deutschen became the official anthem of the Federal Republic, with one rule: Bei staatlichen Veranstaltungen soll die dritte Strophe gesungen werden. (At state events, the third verse is to be sung.) After unification, President Richard von Weizsäcker wrote to Chancellor Helmut Kohl on 19 August 1991 that the third verse ist die Nationalhymne für das deutsche Volk, is the national anthem of the German people. On 23 August 1991, Kohl agreed in writing, namens der Bundesregierung, on behalf of the federal government.