[1] After his return from captivity, Hartmann was discharged from the service with the rank of Oberleutnant, and worked for several years as an engineer and locksmith for an aircraft manufacturer.

He was then transferred to the staff of SS-Oberabschnitt Mitte (Main District – Center) based in Braunschweig until 18 August 1939 when he was dismissed from the SS because of alcoholism.

He also held a seat on the 23 member panel of honorary lay judges (Liste der ehrenamtlichen Mitglieder des Volksgerichtshofs [de]) in the People's Court from April 1934.

He served as the commander of the second battalion of the 2nd SS Police Regiment from February to late June 1943, deployed to Weißruthenien in the Reichskommissariat Ostland.

Leaving that post ahead of the advancing Soviet forces on 31 October 1943, he was named SSPF "Shitomir" in the Reichskommissariat Ukraine (RKU) until 25 January 1944 when the Red Army liberated that area.

[5] Hartmann died on 3 May 1945 of pancreatic cancer, very shortly before the end of the war in Europe, in a hospital in Karlsbad (today, Karlovy Vary).