When Dachau was established in March 1933 the vast majority of the prisoners were German political opponents of the Nazi Party. All political parties, with the exception of the Nazi party, were banned within a year. After crushing the political opposition the Nazis spread the net of oppression by targeting other “undesirable” groups. These new groups of prisoners had to wear not only numbers but also a coloured identification badge.
A red triangle signified a person classified as a “political” prisoner.
Green meant “Professional Criminal”.
Blue meant “Emigrant”.
Purple had to be worn by Jehovah’s Witnesses.
Pink was worn by men persecuted under the anti-homosexual laws.
Black meant “Asocial” which was vague enough to include Roma and Sinti people, sex workers, homeless people, and a whole range of other people who did not fit into what the Nazis would consider normal or correct.
Jewish prisoners were required to wear two triangles: for example a red triangle pointing down in front of a yellow triangle pointing upward - hence this prisoner is labelled as “Jewish political”. For Jews this amounted to what was in effect double persecution: for example persecuted as a Jew and as a political opponent.
Not only was the badge system a way to dehumanise and objectify the prisoners at Dachau, it was also a way to try to split the increasing numbers of prisoners into smaller factions which could be potentially turned against each other. This was one of the many tactics used by the SS to control prisoners in the concentration camps.