[1] From 1964, Jahn was the Deputy Head for Ideological Work at the Office for Industry and Construction within the Politburo of the Central Committee of the SED.

[1] During his time as the top FDJ official, he was informally mocked as 'Jubel-Jahn' ('Jubilant Jahn') due to his impulsive exclamations like 'Long live international solidarity' at political events.

[4] On 17 August 1970, Red Army Faction terrorist Ulrike Meinhof asked for a meeting with Jahn.

[1] In January 1976, he rose to the position of the First Secretary after longtime incumbent Werner Wittig surprisingly died.

[1][2][3][7] Unlike other First Secretaries such as Hans Modrow, Jahn was not one of the prominent figures, strictly executing party decisions.

[2] Jahn took interest in Potsdam's movie industry, personally taking charge of the planning and securing financial aid of the GDR's film museum, opened in 1981.

[1] Though initially opposed to dialogue with demonstrators and reform, Jahn eventually criticized Erich Honecker shortly before his downfall, accusing him of weak leadership and insisting on change.