In April 1945, Hammann, who was the blockälteste of the children's barrack, sabotaged the planned movement of Jews on a death march to a certain extermination.
In 1946, the American authorities questioned Hammann's real role as a privileged prisoner, accused him of active collaboration with the SS and imprisoned him at Dachau concentration camp.
He became a hero in East Germany posthumously when propagandists elevated the antifascist resistance in Buchenwald to the level of a foundational myth of the DDR.
[4] It was a prime example of the "indirect rule system" practiced by the SS, where ethnic German prisoners (political "reds" and criminal "greens") reigned over the "inferior" races.
[6] The youngest, presented as a Pole, was only three years old,[8] another three-year-old Jewish child was born in Buchenwald and raised secretly by the prisoners.
[9] When the privileged "red" prisoners heard rumours of the upcoming evacuation of Jews, they sabotaged preparations for the death march.
[12] He was by no means the sole saviour of the Buchenwald Jews: the separation of children under the tutelage of a prisoner-teacher was influenced by Erich Reschke in summer 1943[7] and continued by Franz Leitner, both communists.
[14] According to American reports and West German Social Democrats, Hammann illegally staffed his office with fellow Communists.
Letters of support by Emil Carlebach and fellow Buchenwald survivors did not impress the prosecution and Hammann was imprisoned at Dachau for a whole year.
[19] The East German doctrine rested on three "pivotal" events - the death of Ernst Thälmann (18 August 1944), the "uprising" (11 April 1945) and the survival of Stefan Jerzy Zweig, the child of Buchenwald.
Independent research by Yad Vashem in 1982 attested to Hammann's "pivotal role" in saving the Jewish children without the "theatrical flourish" of East German propaganda.
A 1996 school essay contest sponsored by the Jewish congregation of Groß-Gerau summarized the problem: "Whether or not a Communist could be a role model for young people in the united Germany?".