After the war, Harzer became active in HIAG, a lobby group established by senior Waffen-SS men in 1951 in West Germany.

He acted as the organisation's official historian, coordinating the writing and publications of revisionist unit histories, which appears in German via the Munin Verlag imprint.

In March 1934 Harzer joined SS-Verfügungstruppe and was assigned to the Sicherheitsdienst and later the SS Division Das Reich.

On Sunday 17 September 1944, the Allies launched Operation Market Garden and Harzer’s division was engaged in the Battle of Arnhem.

[citation needed] After the war Harzer worked as an official historian for HIAG, an organization of former Waffen-SS members.