At this time Gauch was closest to the circles of the Nordicist and neopagan faction within the party led by Himmler, Alfred Rosenberg and Walter Darré.

He wrote six books of "race research" while a member of the SS, expressing both antisemitic and Nordicist ideas, emphasising them to an extent that was extreme even in Nazi Germany.

Gauch argued that, We can advance the assertion that at the base of all Racial Science there is no concept of "human being" in contradistinction to animals separated by any physical or mental trait; the only existing differentiation is between Nordic man, on the one hand, and animals as a whole, including all non-Nordic human beings, or sub-men, who are transitional forms of development.

[4]However Gauch soon caused embarrassment to the leadership when he published Out of the Flower Garden of Racial Research, in which he went further, calling Italians "half-ape".

[5] He also believed that racial mixture led to disease, claiming that "Hereditary cancer is the conflict of races within the human body.

He submitted a proposal to Darré to reform the calendar, getting rid of Christian festivals and replacing them with Germanic pagan ones.

[7] Gauch enlisted on the outbreak of World War II, serving initially in the Luftwaffe, but was later invalided out after damaging his spine in an accident during a training flight.

He subsequently claimed that he had suggested to Himmler the policy of Germanisation in Poland, by absorbing racially suitable Polish children, who showed "Nordic" characteristics.

He ran a hospital in Lauterecken until the final stage of the war, when he was transferred to the Western front, suffering a serious injury in the last few weeks of the conflict.

[2] According to his son, he continued to believe in his racial theories after the war, convincing himself that neo-Nazis would eventually take power in Germany.

[2] Soon after his death in 1978 Sigfrid published Vaterspuren (1979; translated as Traces of my Father), a book which provided a model for later memoirs about coping with a Nazi family background.